PDA-s Manual 20july15 [PDF]

Zitiervorschau

Manual for the PDA 8G and PDA-S Software

Updated: July, 2015

ii

:

iii

Table of Contents Chapter 1: Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.1: Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.2: Dynamic Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.3: History of the Pile Driving Analyzer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.4: Your Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.5: The ‘.pda’ File Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.6: Your Responsibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.6.1: Pile Bearing Capacity Considerations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.6.2: Additional Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.6.3: PDA Operator Proficiency Examination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3 4 5 5

Chapter 2: Hardware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.1: 8G Main Unit and Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2.2: Sensors, Wireless Transmitter, and Cables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 2.3: Charging Your Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 2.4: Charging Your Wireless Transmitters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 2.5: PDA Power Up Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 2.6: External Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.6.1: External Keyboard and or mouse. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.6.2: External Monitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.6.3: Network Connection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

19 19 19 20

Chapter 3: Sensor Attachment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 3.1: General Procedure: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 3.2: Good Policy Measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 3.3: Sensor Checkout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 3.3.1: For Each Strain Transducer: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 3.3.2: For Each Accelerometer: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 3.4: Calibration Pulse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 3.5: Attaching PDA Bolt-On Sensors to the Pile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 Chapter 4: File Setup. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 4.1: Starting the Program. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 4.2: The Title Screen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 4.2.1: Review Previous Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 4.2.2: About . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

:

iv

4.2.3: Configure WiFi . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2.3.1: Adding a 8G Transmitter by Auto Discovery . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2.3.2: Adding a 8G Transmitter by Direct Entry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2.3.3: Changing 8G Transmitters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2.4: Settings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2.4.1: Graph Set-up for Field Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2.4.2: Backup File Settings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2.4.3: Standard Hammer Database Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2.4.4: Custom Hammer Database Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2.4.5: Sensor Database Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

32 32 32 32 33 34 35 35 35 36

4.3: File Set-up. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.1: The Overview Screen. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.2: Project Screen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.2.1: Modifying Pile/Project Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.3: Pile Model Screen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.3.1: Geometric Properties: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.3.2: Material Properties: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.3.3: Capacity Calculation Properties: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.3.4: Entering Splice Locations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.3.5: Length Increments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.3.6: Area Calculator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.4: Sensor Screen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.4.1: Use of Smart Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.4.2: Use of Non-Smart Sensors (Old Style) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.4.3: Selecting Trigger Channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.4.4: Active Channels. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.4.5: Used Channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.4.6: Trigger Levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.4.7: Cabled Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.4.8: 8G Transmitter Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.4.9: Transmitter Battery Meter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.4.10: Sensor Balancing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.5: Hammer Selection Screen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.5.1: Maximum Blow per Minute Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.5.2: Defining a Custom Hammer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.5.3: Hammer Database. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.6: Data Sampling Screen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.6.1: Pretrigger Buffer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.7: Data Limits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.7.1: Target Capacity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.7.2: Velocity Limits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.7.3: Stress and Energy Limits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.7.4: Hammer Stroke / Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

36 36 37 37 38 38 39 39 40 40 42 42 43 43 45 45 45 45 45 45 46 47 48 48 49 50 51 52 52 53 54 55 56

4.4: Proceeding to Data Collection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 4.4.1: Data Validation Screen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

:

v

Chapter 5: Basic Program Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 5.1: The Data Collection Screen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.1.1: The Project and Pile Information Bar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.1.2: Pile Information Window. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.1.3: Output Quantities Window . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.1.4: Pile Penetration and Drive Log Window . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.1.5: Graphing Windows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.1.6: Operations Toolbar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.1.7: The Warnings Bar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.1.8: The Menu Bar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.1.9: Status Bar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

59 60 60 60 61 61 61 61 62 62

5.2: Data Collection--Standby/Accept Modes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62 5.3: Calibration Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 5.4: Graph Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 5.5: Turning Off/On Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66 5.6: WiFi Radio Sub-Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 5.7: Adjusting Time Scales . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 5.8: Completing Data Collection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 5.9: Reviewing Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 5.9.1: Opening a File. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 5.9.2: Data Replay. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 5.10: Battery Meter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71 Chapter 6: Operations Toolbar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73 6.1: iCAP® Quickstart Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74 6.2: The CAPWAP Sub-Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 6.3: Sensor Sub-Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 6.4: Vertical Scale Adjustment Sub-Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 6.5: The Velocity Adjustment Sub-Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 6.6: The Function Sub-Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78 6.7: Time Scale Sub-Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 6.8: The Replay Sub-Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 6.9: Keyboard Entry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 6.10: The Vertical Graph . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 6.11: Data Collection Sub-Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 Chapter 7: Program Customization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83 7.1: Output Quantities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83 7.1.1: Modifying Output quantities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 :

vi

7.1.2: Quantity Precision . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.1.3: Quantity Groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.1.3.1: Changing Quantity Groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.1.3.2: Editing Quantity Groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.1.3.3: Restoring Quantity Group . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.1.3.4: Creating User Defined Quantity Groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.1.3.5: Deleting User Defined Quantity Groups. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.1.4: Common Quantities Defined. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.1.5: Direct Entry of a Quantity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

84 84 85 85 85 86 86 86 87

7.2: Graph Views . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

:

7.3: System Colors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.3.1: Color Schemes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.3.1.1: System Color Schemes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.3.1.2: Customized Color Schemes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.3.2: Exporting and Loading Color Schemes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

88 89 89 89 90

7.4: Output Quantities Title Bar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.4.1: View Selections for Output Quantities Window . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.4.1.1: Output Quantities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.4.1.2: PDA Record . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.4.1.3: Sensor Info . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.4.1.4: More Info . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.4.1.5: Snapshot Info . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.4.1.6: Sensor Views . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.4.1.7: High Contrast Buttons. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.4.2: Graph Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.4.2.1: Calculated Wavespeed Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.4.2.2: Display iCap Results. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.4.2.3: Displaying the Quantity Rank . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.4.2.4: iCAP Auto Fly-out . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.4.2.5: Show Splice Markers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.4.2.6: Verbose Quantity Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.4.2.7: Graph Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.4.2.8: Panel Adjustments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

90 91 91 91 91 91 91 91 91 92 92 92 92 93 93 93 93 94

7.5: Options Menu. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.5.1: Auto Open Most Recently Used File. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.5.2: Calculated Wavespeed Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.5.3: Data ID on Mouse Hover. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.5.4: Display iCap Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.5.5: iCap Auto Flyout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.5.6: Include MKS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.5.7: Record Management. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.5.8: Show Splice Markers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.5.9: Splice Data on Mouse Hover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.5.10: Tension Envelope on Mouse Hover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.5.11: Use High Contrast Icons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

94 94 94 94 94 94 94 95 95 95 95 95

vii

7.5.12: Verbose Tracking. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95 7.5.13: Change Font . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95 Chapter 8: Data Adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 8.1: Assessing Data Quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 8.1.1: Signal Quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98 8.1.2: Proportionality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 8.2: Data Adjustments for Velocity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2.1: Velocity Time Shift . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2.2: Velocity - End Record Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2.3: Velocity - Early Record Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2.4: Smoothing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2.5: Adjusting Time Indicators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

100 100 101 101 102 102

8.3: Changing Calibrations (or Replay Factors) in Existing Files. . . . . . . . . . . . . . . . . . . . . 102 8.3.1: Calibration Adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102 8.3.2: Replay Factor Adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103 8.4: Drive Log Entry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104 8.4.1: Generate Drive Log From Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104 8.4.2: Generate Drive Log From LP Values. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106 8.5: Blow Number Adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.5.1: Incrementing the BN or LP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.5.2: BN/Energy Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.5.2.1: BN Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.5.2.2: Energy Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

107 107 107 107 108

8.6: Modifying Project/Pile Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.6.1: Modification to Project Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.6.2: Modification to Pile Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.6.3: Multiple Pile Profiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.6.3.1: Pile Profiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.6.3.2: Editing Pile Profiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

108 109 109 110 110 110

8.7: Radio Adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111 8.7.1: Radio Data Re-Alignment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111 8.7.2: Wireless Synchronization Correction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112 8.8: Changing Hammer Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 8.9: Preparing files for CAPWAP Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 8.9.1: CAPWAP Preparation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114 8.9.1.1: Final Displacement Correction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114 8.10: File Modifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.10.1: Merging Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.10.2: Hide/View Cal Records . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.10.3: Deleting Blows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.10.4: Reducing Data Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.10.5: Exporting FIles to ‘.w01’ Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

:

115 115 115 115 115 116

viii

8.10.6: Display of Multiple Data Files Simultaneously . . . . . . . . . . . . . . . . . . . . . . . . . . 117 8.11: Saving Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117 Chapter 9: Output. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119 9.1: Creating Output files. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.1.1: Reports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.1.1.1: Printer Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.1.1.2: Report Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.1.1.3: General Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.1.1.4: Generating a Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.1.2: Legacy “HP” Reports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.1.2.1: Printer Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.1.2.2: Report Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.1.2.3: General Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.1.3: Generating a Legacy “HP” Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.1.4: Creating Bitmap Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

119 119 120 120 120 120 121 122 122 123 123 123

9.2: Copy Data to Clipboard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124 9.3: Creating ‘SQ’ File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124 9.4: Exporting files to PDIPlot2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124 9.5: Importing records from PDA-S into CAPWAP® . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124 Chapter 10: Material Property Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125 10.1: Specific Weight Density (SP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125 10.2: Wave Speed (WS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125 10.3: Elastic Modulus (EM). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125 10.4: Relationship between Pile Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126 10.5: Pile Impedance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126 10.6: Computation of ‘SP’ and ‘EM’ for Composite Piles . . . . . . . . . . . . . . . . . . . . . . . . . 127 10.7: Determination of Wave Speed. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.7.1: During Driving . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.7.2: By Proportionality Calculation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.7.3: By Wave Up Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

127 127 129 129

10.8: Variable Wavespeed WC Values. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.8.1: Constant for Pile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.8.2: Blow by Blow Auto Edit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.8.3: Blow by Blow Edit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.8.4: Use of LS to determine appropriate WC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

129 130 130 130 130

Chapter 11: Capacity Determination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131 11.1: Capacity Evaluation Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131 11.1.1: Capacity Gain/Loss with Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131

:

ix

11.1.2: Capacity Mobilization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133 11.1.3: Correlation with Static Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133 11.2: Capacity Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.2.1: Case Method Capacities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.2.1.1: RSP Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.2.1.2: Shaft Resistance Estimation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.2.1.3: End bearing Capacity Estimation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.2.1.4: RMX Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.2.1.5: RAU/RA2 Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.2.1.6: RSU Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.2.2: Damping Constant JC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.2.3: CAPWAP Capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.2.4: iCAP Capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.2.5: Energy Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

134 134 135 135 136 137 137 138 138 139 140 141

11.3: Additional Considerations/Suggestions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141 Chapter 12: Pile Stresses. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143 12.1: Stresses - Significance and Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.1.1: Compression Stresses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.1.2: Static Bending Stresses on Piles Driven on an Incline . . . . . . . . . . . . . . . . . . . . . 12.1.3: Stresses at the Pile Toe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.1.4: Tensile Stresses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

143 143 144 144 145

12.2: Tension Envelope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146 12.3: Recommended Stress Quantities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146 12.4: Stress Limits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147 Chapter 13: Hammer Performance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149 13.1: Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149 13.2: Energy Measurements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149 13.3: Hammer Stroke (Open-Ended Diesel Hammers) . . . . . . . . . . . . . . . . . . . . . . . . . . . 150 13.4: Calculations for External Combustion Hammers . . . . . . . . . . . . . . . . . . . . . . . . . . . 150 13.5: SPT Energy Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151 13.5.1: Historical note on SPT Energy Calculation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151 Chapter 14: Pile Integrity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153 14.1: BETA (Integrity / Damage Evaluation) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153 14.2: Beta Window . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156 14.3: Beta Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156 Chapter 15: iCAP® Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159 15.1: Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159

:

x

15.2: iCAP Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.2.1: iCAP Analysis Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.2.1.1: iCAP Qualifiers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.2.1.2: ‘iCAP [#] Blows’ Criteria. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.2.1.3: Start iCAP Fresh for Each Record . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.2.1.4: Save iCAP Result . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.2.1.5: Quick iCAP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.2.1.6: iCAP Timeout (min). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.2.2: Additional Analysis Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.2.2.1: iCAP New Doc . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.2.2.2: iCAP Send FV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.2.2.3: iCAP Send FV Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.2.2.4: iCAP Cancel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.2.2.5: iCAP Stop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.2.2.6: iCAP Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

160 161 161 163 163 163 164 164 164 164 164 165 165 165 165

15.3: Running iCAP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.3.1: iCAP Operation During Data Collection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.3.2: iCAP Operation During Data Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.3.3: iCAP Analysis Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.3.4: Viewing iCAP Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

165 165 166 166 166

15.4: Understanding the iCAP Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168 15.5: iCAP Output Quantities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169 15.6: Manipulating the iCAP Scales . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169 15.7: Modifying iCAP Qualifiers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170 15.8: Continuing iCAP Analysis During Data Acquisition . . . . . . . . . . . . . . . . . . . . . . . . . 170 15.9: iCAP Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170 15.9.1: Modifying the iCAP Result . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170 15.10: PDIPlot Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170 15.11: iCAP External Inputs (BLC and LP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170 15.11.1: Penetration Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170 15.11.2: Blow Count Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171 15.12: iCAP Methodology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171 15.13: iCAP Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172 Chapter 16: SPT Data Collection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175 16.1: SPT Program Notes and Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176 16.2: File Set-up. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.2.1: The Overview Screen. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.2.2: Project Screen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.2.3: Rod Model Screen. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.2.3.1: Geometric Properties: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.2.3.2: Material Properties: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

:

176 176 178 179 179 179

xi

16.2.3.3: Length Increment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.2.3.4: Area Entry using Smart Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.2.3.5: Area Entry without Smart Sensor programming. . . . . . . . . . . . . . . . . . . . . . 16.2.4: Sensor Screen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.2.4.1: Use of Smart Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.2.4.2: Use of Non-Smart Sensors (Old Style) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.2.4.3: Selecting Trigger Channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.2.4.4: Active Channels. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.2.4.5: Used Channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.2.4.6: Trigger Levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.2.4.7: Sensor Balancing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.2.5: Hammer Selection Screen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.2.6: Data Sampling Screen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.2.6.1: Pretrigger Buffer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.2.7: Data Limits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.2.7.1: Velocity Limits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.2.7.2: Energy Limits. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.2.7.3: Hammer Stroke / Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

179 180 181 182 183 183 185 185 185 185 185 186 187 188 188 188 189 190

16.3: Proceeding to Data Collection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190 16.3.1: Data Validation Screen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190 16.4: Program Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191 16.5: Data Analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191 16.6: Report Generation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.6.1: Creating an SPT Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.6.1.1: Defining Sample Intervals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.6.1.2: Validating Sample Intervals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.6.1.3: Deleting Sample Intervals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.6.1.4: Auto-Defining Sample Intervals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.6.1.5: Defining Headers in Reporting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.6.1.6: Defining Output Quantities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.6.2: Reporting Options. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.6.2.1: General Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.6.3: Creating a Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

192 192 193 193 193 193 193 193 194 196 196

Chapter 17: Recommended Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199 17.1: Sample Project Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199 17.2: Technical Papers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17.2.1: Correlation Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17.2.2: General Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17.2.3: Integrity Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17.2.4: Soil Set-up/Relaxation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17.2.5: Bored Foundations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17.2.6: iCAP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

199 199 200 200 200 200 200

17.3: Product Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200

:

xii

Appendix A: The Case Method, Wave Mechanics, Theory and Derivations . . . . . 201 A.1: The Wave Speed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204 A.2: Proportionality and Pile Impedance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207 A.3: Basic Wave Mechanics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A.3.1: The Wave Equation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A.3.2: Upward and Downward Traveling Waves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A.3.3: The Classical Reflection Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

209 209 212 214

A.4: Soil Resistance Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A.4.1: Resistance Waves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A.4.2: Shaft Resistance from Force-Velocity Difference. . . . . . . . . . . . . . . . . . . . . . . . . . A.4.3: Resistance from Wave-up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A.4.4: Calculating the Soil Resistance from Wave-up and Wave-down . . . . . . . . . . . . . . A.4.5: Calculation and consideration of soil damping . . . . . . . . . . . . . . . . . . . . . . . . . . A.4.6: Selection of time t1 and the RMX method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A.4.7: Other methods of interest: RAU, RA2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A.4.8: The Unloading Correction Method, RSU . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A.4.9: Total and static shaft resistance (skin friction). . . . . . . . . . . . . . . . . . . . . . . . . . . A.4.10: Energy Approach Capacities QUS, QUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

217 217 218 221 222 226 229 231 232 233 238

A.5: Stress Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A.5.1: Pile top (sensor location) stresses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A.5.2: Pile toe stresses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A.5.3: Pile tension stresses caused by Wave-up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A.5.4: Pile tension stresses caused by Wave-down . . . . . . . . . . . . . . . . . . . . . . . . . . . .

240 240 240 242 247

A.6: Damage Detection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 248 A.7: Hammer Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253 A.8: Results of Example Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257 Appendix B: Quick Set-up Guide. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271 B.1: Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271 B.2: Pile Preparation and Sensor Attachment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271 B.3: Equipment Set-up and Program Initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 272 B.4: Procedure to Enter Project and Test Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . 275 B.5: Procedure for Collecting and Evaluating Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 280 B.6: Sensor Removal. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283 B.7: Exiting the Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283 B.8: Procedure for Data Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283 B.9: Data Reporting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 284 Appendix C: Drilling Guides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285 Errata . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 291 :

xiii

Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 293

:

xiv

:

Chapter 1: Introduction 1.1 Introduction The 8th generation Pile Driving Analyzer®, hence “model 8G” or “8G” (PDA-8G), from Pile Dynamics is a very useful tool for measuring and determining the effects of impacts on a deep foundation element such as a driven pile. The impact is often applied by the pile driving hammer on a driven pile, but the impact may also be imposed by a large drop weight applied to a bored or augered pile, or drilled shaft. The PDA monitors acceleration and strain sensors which are quickly attached to the pile by bolts, and processes these signals after each impact during driving or restrike. The signals are digitized by the PDA, results are computed, and the data array of the signals for a blow is stored. The PDA-S program either controls the data acquisition for the 8G, or can reprocess existing files on an office computer. The data may be interpreted for pile bearing capacity, compression stresses induced at top and bottom, tension stresses along the shaft, energy transferred to the pile or shaft, and pile integrity.

1.2 Dynamic Testing Dynamic pile testing is truly a routine procedure no longer confined to researchers. With over a 50 year history of reliable performance, it has been proven cost effective and reliable, and as a result many contractors, consultants and government agencies have acquired the necessary equipment to assess pile installation or evaluate the bearing capacity of a foundation element; others prefer to obtain the testing as a service from those offering such testing services. The procedures for dynamic pile testing have been documented well in the ASTM standard D4945 (“Test Method for High Strain Dynamic Testing of Deep Foundations”). In addition, numerous construction specifications or building codes reference dynamic testing as either a required or an allowable method (e.g. in the USA, both IBC and AASHTO), and usually such codes require “signal matching” which is the generic name for CAPWAP®. CAPWAP is also “state-of-practice” and the final solution for capacity and stress analysis for dynamic testing data. Progressive codes like LRFD (Load

Introduction: Introduction

2

and Resistance Factor Design, as used by AASHTO) give favorable resistance factors and hence an economic incentive for dynamic testing, resulting in reduced cost of testing (compared to static testing), less risk, and significantly lower overall foundation costs compared with designs from less favorable simple static analysis or dynamic formula methods. Microprocessors have revolutionized our everyday lives from hand calculators to microwave ovens to smartphones. Computers previously were large, unfriendly, and relatively inaccessible. However, since the advent of personal computers, computers have steadily become smaller, faster, and more powerful such that they are now virtually everywhere and used in all facets of instruction and engineering. They have been of great benefit to the civil engineer in solving complex analysis problems. For example, it has been said that wave equation analysis of pile driving was the first non-military application of electronic computers to an engineering problem. The PC has made the PDA a user friendly device. The new PDA-S program is a further step in this direction. The touchscreen operation of the 8G makes data acquisition simple and intuitive. The same PDA-S software on the office computer can use either a touchscreen or keyboard and mouse, depending on the computer hardware and operating system.

1.3 History of the Pile Driving Analyzer The first analog dynamic pile test hardware was built at Case Western Reserve University in about 1968. In 1972, Pile Dynamics (PDI) introduced its first commercial device (Model DA, then called the “Pile Capacity Computer”). The first use of the name “Pile Driving Analyzer” (often simplified to PDA) came in 1974 with introduction of PDI’s Model EA. In 1981, PDI delivered its first fully digital PDA (the “blue box” Model GA) based on the Motorola 68000 microprocessor (delivered before the Apple MacIntosh based on the same microprocessor became available). The GA was updated to GB, then GC, then GCXS in about 2 year intervals. With emerging PC technology, PDI developed a PC version of our PDA in 1989 (called the “GCPC”) and subsequently the (PAK) in 1991. The PAL was developed in 1996 and a remote version was then offered about 1997; the remote testing capability has been offered in all subsequent PDA units. The PAX then was engineered in 2007 and the wireless capability was introduced in 2008. The PDA program for the GCPC and the original PAK was a DOS program (PDA.exe). The windows version (PDA-W) of the processing software was developed in 1996, and serviced data from all PDA units then in operation (GCPC, PAK, PAL and later the PAX). The PDA-W program was updated many times as new capabilities were added. With the introduction of the 8G, a completely new data acquisition and post-processing program was written. This “PDA-S” software combined the ease of field operation for data collection of the PAX with the familiarity and power of the PDA-W post-processing software; engineers already operating the PAX and PDA-W should have a very easy transition to the PDA-S software. Both the PDA-W and PDA-S programs are the portal for data entry into the CAPWAP signal matching software, as well as for PDIPLOT2 and PDICurves. The program was designed with software control functions given through keyboard entry or clicking Menu Bar selections or ICONS. The program makes frequent use of dialog boxes which guide the user in a logical way. The calculated values for (an almost unlimited) selected parameters (Q1, Q2, Q3…Qn) are displayed and can be automatically summarized as required by ASTM D4945 by the

Introduction: History of the Pile Driving Analyzer

3

PDIPLOT2 program. Using the PDA-Curves program, plots of various blows can be combined into one page. There is considerable “HELP” available. The main operating manual is available as Help electronically on the screen through the help menu or by pressing the [F1] key. PDA-S also evaluates the data quality and display “warnings” for the new user if something appears to be wrong. The software lets the user enter limits on output results providing for automatic comparison with testing results; any values exceeding the limits are highlighted. Because everything is controlled by touchscreen, mouse, or keyboard, and only one program is needed for both data collection and post-processing, the training process is simplified and expedited. Extra time can be spent on theory and practical applications. It makes introduction to new PDA operators less time consuming.

1.4 Your Safety CAUTION! PILE DRIVING can be HAZARDOUS! It's YOUR RESPONSIBILITY to ensure safe working conditions. Use all suggested and required safety equipment. THINK and BE PREPARED, especially with power (we suggest you use the internal 8G battery, or an external 12 volt D.C. battery for the PDA to avoid the risk of high voltage/line power, and battery powered drills whenever possible to prepare the pile for sensor attachment. The 8G model of PDA has self-contained replaceable battery power for nominally 4 hours operation which may be swapped out with another battery. For attaching sensors to pile, attaching the sensors and wireless transmitter on the ground prior to lofting the pile and protecting them with the supplied “sensor protectors”, is often possible and then preferred. Further the use of wireless data transmission with the 8G avoids the need for a cable connection between sensors and PDA and, therefore, avoid damaging main cables during pile lofting or driving monitoring. Again sensor protectors then cover the sensors and transmitter, protecting them during the pile lifting process, and eliminating the need to climb the leads to attach the sensors. This therefore not only improves safety, but also speeds up the testing process. If the sensors must be attached shortly after the pile is placed in the leads, we suggest that you give proper instructions and allow the pile driving crew to climb the leads and attach transducers. Remember that YOUR SAFETY IS YOUR FIRST PRIORITY; avoid dangerous tasks or situations. It is particularly important to observe the lifting of the pile process (and plan your potential escape route in advance). Do not stand near or approach the pile when the hammer is in operation.

1.5 The ‘.pda’ File Format Any W01 file created by any PDI Pile Driving Analyzer (model: PAK, PAL, or PAX) can be reanalyzed by the PDA-S program. There may be some files whose origin is uncertain and thus cannot be interpreted properly, the PDA-S program will refuse to open these files since the calibration is uncertain. The PDA-S program will also read SPT Analyzer files, although some functions will not work. Windows 7 is the minimum operating system.

1.6 Your Responsibility The 8G running PDA-S is a very powerful tool when used properly to assess the entire pile driving process. The minimum suggested education for a person to operate the PDA is a FOUR YEAR ENGINEERING DEGREE with preferably a civil or geotechnical specialty.

Introduction: Your Safety

4

Final result interpretation should only be by a LICENSED PROFESSIONAL ENGINEER who understands wave propagation theory, pile design, pile driving, and preferably has an understanding of the geotechnical aspects of the project; a complete training program is highly recommended. Training materials include PowerPoint presentations and “Example Data”. Of course, reading the PDA-S manual and therefore knowing its contents is essential. While it may appear that PDA operation is relatively simple and that anyone can do it, actually each job presents unique challenges and often recommendations or other data interpretations should be made on site. This is particularly true for special test programs or for the first dynamic test piles driven on site to verify the preliminary driving criteria; in these cases, there are also often many ‘visiting dignitaries’, and decisions made at this crucial time often can influence the overall foundation cost. Assigning this responsibility to a technician, or an engineer with no background in dynamic pile testing or PDA operation, is not good practice, and must be avoided as it increases liability. A geotechnical engineer should review results for uplift, settlement, downdrag, seismic considerations, changes to the water table, surcharges and any other geotechnical or structural conditions which are beyond the possible solutions provided by PDA testing. It is expected that you, the PDA operator, will become or are familiar with all aspects of data acquisition and analysis to assure that correct interpretations be made. This implies first that you begin by thoroughly reading the PDA MANUAL in its entirety and understanding the theory, principles, applications, and limitations as they apply to your situation. While data interpretation and application of your results are entirely your responsibility, after you have studied the manual, you should not hesitate to contact PDI for further information. We appreciate your input in making this document easier to read and understand. Furthermore, you should also seek advice and ask for the review of your work from those with more experience in your organization or elsewhere. Peer review is good practice.

1.6.1 Pile Bearing Capacity Considerations It should be noted that the dynamic testing estimates for the pile capacity indicate the mobilized pile capacity at the time of testing. At very high blow counts (low set per blow), dynamic test methods tend to produce lower bound capacity estimates as not all resistance (particularly at and near the toe) is fully activated. At refusal blow counts in restrike, and only at refusal blow counts in restrike, a superposition of restrike shaft resistance with end of drive end bearing may be reasonable provided the bearing layer is not susceptible to relaxation. Static pile capacity from dynamic testing estimates the axial pile capacity. Increases and decreases in the pile capacity with time typically occur (soil setup/relaxation). Therefore, dynamic testing during restrike tests usually yield a better indication of long term pile capacity than a test at the end of pile driving. The capacity of a pile at the time of driving may often be less than the long-term pile capacity, particularly for piles driven in fine grained soils (clays, silts and even fine sands). During pile driving, excess positive pore pressures are often generated. These pore pressures reduce the effective stress acting on the pile thereby reducing the soil resistance to pile penetration, and thus the pile capacity at the time of driving. As these pore pressures dissipate, the effective soil stresses acting on the pile increase as does the axial pile capacity. This phenomena is routinely called soil setup. Most projects benefit from such capacity increases due to

Introduction: Your Responsibility

5

these pore pressure effects or due to “aging” or “arching” caused by lateral movement during installation. Relaxation (capacity reduction with time) has been observed for piles driven into weathered shale, and may take several days to fully develop. Pile capacity estimates based upon data from either initial driving or short term restrike tests can significantly overpredict long term pile capacity. Therefore, piles driven into shale should be tested after a minimum one week wait either statically or dynamically. It is then particularly important to analyze and rely on the results obtained from the first few blows of the restrike. Relaxation has also been observed for displacement piles driven into saturated dense silts or fine sands due to a negative pore pressure effect at the pile toe. Again, restrike tests should be used, with great emphasis on “high energy early blows”; often a wait period of one or two days is satisfactory but depends on the soil permeability. Larger diameter open ended pipe piles (or H-piles which do not bear on rock) may behave differently under dynamic and static loading conditions due to soil plugging effects or friction between the soil plug and the pile. Numerous other factors are usually considered in pile foundation design. Some of these considerations include additional pile loading from downdrag or negative skin friction, soil setup and relaxation effects, cyclic loading performance, lateral and uplift loading requirements, effective stress changes (due to changes in water table, artesian water pressures, excavations, fills or other changes in overburden), settlement from underlying weaker layers and pile group effects. These factors cannot be evaluated by dynamic pile testing and therefore cannot be evaluated by either PDA-S or CAPWAP. The geotechnical engineer of record or the foundation designer should determine if any of these considerations are applicable to the project and the foundation design. The results based on the PDA data should only be one of the considerations leading to the acceptance of the foundation element for a certain loading. Comparison of unit friction results from CAPWAP with expected soil strengths (or upper limiting values) should be performed. The resistance distribution should be evaluated, and adjusted if needed, particularly near the pile toe. CAPWAP analysis is considered an essential part of good PDA practice, but it too has to be undertaken by a well trained and experienced engineer.

1.6.2 Additional Resources It should be noted that there is a considerable body of literature (e.g. PUBLICATIONS on many topics) available on Pile Dynamics’s website (http://pile.com/reference/) in the RESOURCES area of our technical library. It is strongly suggested the practicing PDA tester should read many of these papers, both to gain understanding and as an aid when discussing issues with the client. The website offers sample specifications for insertion into job specification (and can be edited to fit the specific client or project). All technical information is available free of charge when downloading.

1.6.3 PDA Operator Proficiency Examination There is a growing need for evaluation of knowledge and ability to properly collect and interpret PDA data. Pile Dynamics in cooperation with the Pile Driving Contractors Association (PDCA) now offers an examination which assesses the PDA operator’s knowledge of the principles of dynamic testing. Information about the examination, and

Introduction: Your Responsibility

6

its objectives can be found at www.PDAProficiencyTest.com. The test covers five facets of dynamic testing: theory, interpretation, application, data quality and CAPWAP. A breakdown score in each of these areas is provided to everyone taking the test. A certificate is issued to the engineer who passes the test showing his relative degree of knowledge (“rank”); this is simply a statement attesting to knowledge and not a certification. It is recommended that specifying agencies and government authorities require PDA users to take the proficiency examination as part of their overall quality assurance programs, and to set their own minimum achievement levels and test expiration duration. In fact several USA State Departments of Transportation now require this examination result prior to working on their projects.

Introduction: Your Responsibility

Chapter 2: Hardware

Figure 2.1: PDA 8G Unit with WiFi Radio and Sensors

Hardware:

8

2.1 8G Main Unit and Accessories

5

4

4

3 2

6 7 8 9

1 Figure 2.2: 8G PDA Main Unit

The 8G Main Unit has the following input/output ports •

1 - On-off switch (with embedded LED)

•

2 - 12 Volt DC input

•

3 - Battery Charger input

•

4 - Universal Main Cable Input (2)

•

5 - Remote blow count switch input

•

6 - USB ports (4)

•

7 - Ethernet port

•

8 - External Monitor VGA output

•

9 - HDMI output

Hardware: 8G Main Unit and Accessories

9

11 10 12 Figure 2.3: PDA 8G rear view •

10 - Collapsing stand

•

11 - Antenna

•

12 - Battery Access

Figure 2.4: 8G Main Unit with stand extended

Hardware: 8G Main Unit and Accessories

10

Figure 2.5: 8G Main Unit Charger The 8G main unit charger with LED charging status indicator is used to charge the internal battery of the main unit without removing the battery. When charging, the LED will glow orange-red and, when charging is complete, the LED will switch to green. This connects to the charging input connector on the 8G. The appropriate power cord should be used to connect the charger to the power supply outlet.

Figure 2.6: Replaceable Internal Battery Internal Battery - 10.8V Lithium Ion Battery, provides nominally 4 hours of use when fully charged. Additional batteries are available. Each replaceable battery has an LCD display to show the battery charge remaining. Batteries may be replaced after the system has been powered down then removing the back plate by unscrewing the thumb screws and replacing with a fully charged battery unit.

Hardware: 8G Main Unit and Accessories

11

Figure 2.7: External Battery Charger

Figure 2.8: Battery Charging in External Charger The Batteries to the 8G Main Unit may be charged also using the external battery charger. This will allow a user to charge a spare battery that is not in use while operating the 8G main unit on a different battery or alternate power supply. The appropriate power cord should be used to connect the charger to the power supply outlet

Hardware: 8G Main Unit and Accessories

12

Figure 2.9: DC Power Cable DC Power Cable - When using external 12 Volt DC power (such as a car battery), first connect the POSITIVE (+) battery terminal to the red wire. The black wire then goes to a NEGATIVE (-) ground point. Avoid making a spark near lead acid batteries by connecting the black wire to a good ground point on the vehicle away from the battery.

Figure 2.10: AC Power Supply The AC Power Adapter for th 8G Main Unit has a rated input voltage maximum of 18V. Exceeding this voltage may damage the 8G and void the warranty. Only use AC power supply units from Pile Dynamics, Inc.

Hardware: 8G Main Unit and Accessories

13

Figure 2.11: Remote Blow Count Switch The remote blow count switch allows the user or other site personnel to update the penetration indicator (LP) during driving.

2.2 Sensors, Wireless Transmitter, and Cables

Figure 2.12: Main Cable The Main cable connects splitter cable (Figure 2.17). to the PDA-8G main unit.

Hardware: Sensors, Wireless Transmitter, and Cables

14

Figure 2.13: Wireless Transmitter Wireless Transmitter - Connects to two transducers (two strains, two PR accelerometers, or one strain and one accelerometer). To turn on, plug the leftmost cap (power switch connector) into the port and secure by twist locking it. It is important to note that even when not collecting data, the wireless radio battery still discharges when the power switch is twist locked and secured. When powering on the Wireless Transmitter, the LEDs will immediately begin to cycle through all available colored lights. During the power up cycle Channel 1 (CH1) and Channel 2 (CH2) will start red, switch to green, and then CH2 will switch to blue while CH1 will turn off. After quickly switching back to green, CH2 will hold blue while CH1 will be off. Following the completion of the power-up cycle the status of the transmitter can be evaluated from the LEDs using Table 2.14.

Hardware: Sensors, Wireless Transmitter, and Cables

15

Table 2.14: Wireless Transmitter LED Information Ch 1

OFF

Ch 2

Searching for 8G to connect to

Sensor on Ch1 Balanced; Searching for 8G

Searching for 8G, Wireless Transmitter low battery

Attached sensors connected and balanced

Sensor on Ch1 unbalanced, Sensor on Ch2 balanced

Sensor on Ch1 balanced, Sensor on Ch2 unbalanced

Both sensors unbalanced

Figure 2.15: Wireless Transmitter Charger The Charger for Wireless Transmitter - LED will glow red-orange while charging and change to a bright green when charging is complete. Typical charging times are approximately 3 hours to achieve a full charge. Connect to the power switch connector on the Wireless Transmitter to charge the internal battery of the wireless transmitter.

Hardware: Sensors, Wireless Transmitter, and Cables

16

Figure 2.16: Sensor Adapters (Old connections to new universal connection) Adapter cables are used for older model Strain gages, PR accelerometers, or PE accelerometers, sensor specific adapter cables can be provided. One end is the input for the sensor while the other end attaches to the wireless transmitter or splitter cable.

Figure 2.17: Splitter Cable The Splitter Cable connects sensors to main cable. Any sensor may be plugged into any of the 4 channels and will recognize Smart Sensor technology. The 8G will recognize which sensor is plugged into each channel and will automatically select the appropriate signal conditioning and read the programmed sensor calibration.

Hardware: Sensors, Wireless Transmitter, and Cables

17

Figure 2.18: Strain Sensor A Strain Sensor enabled with “Smart Sensor” technology will report its serial number and calibration correctly when using either cables or wireless transmitters. Specifications can be found at our website (www.pile.com)

Figure 2.19: Piezoelectric (PE) Accelerometer

Hardware: Sensors, Wireless Transmitter, and Cables

18

Piezoelectric (PE) Accelerometers enabled with “Smart Sensor” technology will report its’ serial number and calibration correctly when using either cables or wireless transmitters. Specifications can be found at our website (www.pile.com).

Figure 2.20: Piezoresistive (PR) Accelerometer Piezoresistive (PR) Accelerometers enabled with “Smart Sensor” technology will report its serial number and calibration correctly when using either wireless transmitters or cables Specifications can be found at our website (www.pile.com)

2.3 Charging Your Unit The batteries powering the 8G unit can be charged either with the battery attached inside the unit or with the battery removed from the unit and placed in the external charger. To charge the battery internally, the 8G Main Unit Charger (Figure 2.5) should be plugged into an AC power source and twist locked into the plug noted by the lightning bolt (connector 3 from Figure 2.2). To charge batteries externally, plug the external battery charger into an AC power source and mount the battery in the battery bay. When charging a battery internally, the main 8G unit may be run at the same time. This will both power the system and charge the battery. When charging the system, the 12V power inputs can be used at the same time to power the system while the battery charges. During this operation, the battery does not have its charge drained, it only charges. The 8G unit takes the 12V input as a priority input for power. When fully discharged, a battery will take approximately three and a half hours to fully recharge. The LCD display on the battery will show how much charge is left in the battery in increments of 20%. When charging, the next 20% “block” will blink on the LCD display. The charger also indicates the charging status of your battery. The LED on the 8G Main Unit Charger will flash green when the battery is charging and will be solid

Hardware: Charging Your Unit

19

green when charging is complete. If the LED is solid red, there is a charging error. The external battery charger also has an LCD charging status indicator. It is always recommended to fully charge the 8G the day before testing using the provided battery charger.

2.4 Charging Your Wireless Transmitters Plug the wireless transmitter charger into an AC power source and the charger's twist lock connector into the wireless transmitter's power switch input connector. On the wireless transmitter charger (Figure 2.15), the LED will glow red-orange while charging and change to a bright green when charging is complete. No LEDs on the wireless transmitter itself will turn on and the transmitter will not operate when connected to the charger as power only goes to the transmitter when the cap is twist locked in place.

2.5 PDA Power Up Procedure Press and briefly hold the on-off button. The green LED embedded in the button will turn green and the screen will turn white and eventually display the windows desktop. The 8G comes equipped with an internal battery good for four hours of operation. If the battery runs low, you can run the 8G connected to a 12 Volt external power source (e.g. car battery) with the DC power cable (Figure 2.9) connected to the 12 Volt input. For office use, the 8G also comes with an AC power supply (Figure 2.10) that connects to an AC power source (100 to 250 Volts AC, 50 to 60 Hz). The output of this supply should be connected to the 12 Volt input on the 8G Main Unit. If an external power source is required during field operation, we recommend using a DC power source. For DC power: The following power specifications are important. When using 12 Volt DC power, first connect the POSITIVE (+) battery terminal to the red wire. The black wire then goes to a NEGATIVE (-) ground point. Avoid making a spark near lead acid batteries by connecting the black wire to a good ground point on the vehicle away from the battery. If external power is required, it is highly preferred to run the 8G from the DC connection to a car battery as AC power sources may induce signal noise into the record. For AC power: The 8G also comes with an external power supply that connects to the main supply (100 to 250 Volts AC, 50 to 60 Hz). The output of this power supply should be connected to the 12 Volt input

2.6 External Inputs 2.6.1 External Keyboard and or mouse An external keyboard and mouse can be plugged into the USB ports. Both touchscreen and external keyboard work in parallel, and can both be used simultaneously. The 8G's touchscreen is designed for harsh field environments. However, an external keyboard and mouse provide backup flexibility if the touchscreen fails to operate properly.

2.6.2 External Monitor The 8G can use an external monitor via the VGA connector or HDMI connection.

Hardware: Charging Your Wireless Transmitters

20

2.6.3 Network Connection The 8G Main Unit comes equipped with an Ethernet Port (connection 7 in Figure 2.2). Compatibility requirements with your companies network must be defined and determined by your company’s Network Administrator.

Hardware: External Inputs

Chapter 3: Sensor Attachment 3.1 General Procedure:

The sensors should be firmly attached to steel piles as the high acceleration could cause slippage, resulting in inconsistent and therefore erroneous data. If the strain sensor is not secured properly, damage to the sensor could also result. For concrete piles over-tightening the sensors may result in pulling of the anchors instead; it is therefore very important to firmly seat the anchors. It is always very important to have both strain sensors working properly since unavoidable bending usually makes the strain signals on opposite sides quite different. If a strain sensor fails partway through a test, it should be replaced immediately with a good working unit. The sensors should be attached diametrically opposite the pile neutral axis so that bending is canceled. It should be noted that strain is being measured and then converted to force using the cross sectional area and the assumed modulus of elasticity of the pile material. It is

Sensor Attachment: General Procedure:

22

further assumed, and required, that the pile is of a linear elastic material. In high strain situations, the pile material may go into the plastic range and pile top damage may result. This could result in unrealistic and inconsistent strain measurements, and therefore erroneous forces, stresses, energies and capacities. Since the acceleration signals are generally very similar, one good unit is normally all that is required for a successful test. A second accelerometer serves as backup and also confirms both accelerometers are properly functioning when they do yield similar velocity data. The transducers also should (if at all possible) be attached at least two and preferably three or more diameters below the pile top to avoid end effects and local contact stresses. In general for steel piles or pre-stressed concrete piles, the farther from the pile top the sensors are attached, the better quality the data becomes. The only difference lower sensor placement makes is that the maximum energy (EMX) is reduced due to the energy required to compress the pile above the transducers. Attaching near cross section changes, cracks, welds (horizontal, axial, or spiral), splices, stiffeners or other nonuniformities should be avoided. It should be noted that “telltale” pipes cause complications which must be properly accounted for. For regularly reinforced concrete piles (not prestressed), the transducers should always be near the pile top (within 1.5 to 3 diameters of pile top) to avoid including cracks between the strain transducer attachment points which could induce serious errors. For drilled shafts, using four strain transducers is strongly recommended as it produces better data, especially if attaching two diameters below the top is impractical. Composite sections, such as a fully cased drilled shaft, require special considerations for material properties which are outlined in Section 10.6 on page 127.

3.2 Good Policy Measures As a word of caution, the following safety measures during sensor attachment and subsequent field testing are recommended. • Construction sites can be dangerous. Safety should always be your first priority. Do not place your head and hands between the hammer and pile. Avoid standing near the hammer or pile while in operation and do not stand under any object being lifted. Falling objects cause serious injuries. Plan an escape route before you need it. If you feel endangered stop what you are doing until the situation is corrected. • The 8G unit has a replaceable battery, and pile preparation is commonly done with battery powered drills. However, if corded drills are used, be sure a generator with adequate power will be available. The generator should be properly grounded. Take all precautions necessary to avoid potentially fatal electronic shock if using an AC power source. • In bad weather (cold, rain, etc.), place the 8G unit in your car or other shelter. Keep the unit warm and dry. If the ambient air temperature is warm, it is highly advisable to shade the unit from direct sun. In extreme conditions, air conditioning may be beneficial. • Be sure all sensors, drills, bolts, and tools are with you at any test site. Assemble and test sensors and cables or wireless transmitters on the ground to avoid delays to the contractor. • If sensors are to be attached a significant distance above ground, obtaining the assistance of the pile driving crew to attach sensors is highly recommended. Take

Sensor Attachment: Good Policy Measures

23

precautions to prevent serious injury, such as wearing appropriate personal protective equipment and following all site safety requirements. PDI offers “sensor protectors” which cover the sensors attached to the pile and wireless transmitters when applicable prior to lifting the pile. The sensor protectors then reduce the possibility of damage to the sensors and wireless transmitters in the lifting process, speed up the sensor attachment process, eliminate the need to climb the leads at all in many cases, and thus are highly recommended by PDI. With using sensors and wireless transmitters with the 8G system, along with sensor protectors, no climbing should be needed except to retrieve the system at the conclusion of the test if the sensors are not then at ground level. • The better you treat your equipment, the longer it will last. Do not drop the accelerometers. Do not step on strain sensors. Keep cables from being cut. Keep all connectors and 8G transmitters above water. Do not tie the cable to the leads since, if the pile is being driven, the cables could be severed. Do not allow construction vehicles to run over your cables. • Record site observations including hammer detail, cushion description, date and time of testing (and of initial pile installation, and of static test if any), pile penetrations, etc. Make appropriate notes on PDA data file using built in notes. Record blows per unit penetration (i.e., per foot, inch, meter, etc.) for each pile or obtain records collected on site. Use of smartphone cameras is beneficial to record documents on site such as blow count logs and soil profiles. Photograph the sensors on the pile. Maximum displacement can be obtained from DMX; setrebound measurements are discouraged for safety reasons and due to the significant technical shortcomings of pile driving formulae.

3.3 Sensor Checkout Prior to attaching sensors to the pile, sensors should be checked to avoid bad data or the need to replace sensors already attached to the pile. In the sensors tab of the file setup, all transducers should be selected as active (ACT), used, and as triggers (TRIG) for sensor checkout (see Section 4.3.4.3). Then set up a file for data collection by clicking on the Collect button.

3.3.1 For Each Strain Transducer: • The A/D offset voltage for each transducers is shown in the sensors tab of the file setup dialog box below each sensor (“Sensor Balancing” on page 47). Unbalanced sensors are indicated by a large red X over the sensor serial number. • With the 8G in collect mode and the transducer trigger selection turned on, Tap the strain transducer on one end lightly with your hand while holding on the wired end. A reasonably repetitive trace will be observed. Tapping with the knuckle or a pencil will produce a sharper signal while hitting with a softer heel of hand will produce a more rounded appearance. Do not strike with a hammer or other heavy metal or hard plastic object as damage to the transducer may result. • When finished testing all strain transducers, make sure the Transducer Selection on the sensor bar shows all strain sensors (either two or four as selected) are active. Strain sensors MUST be used in pairs to cancel bending effects, so the minimum number of working strain sensors for a test is two. If one becomes bad, then it must

Sensor Attachment: Sensor Checkout

24

be replaced, or its paired sensor turned off (if using four sensors, and one goes bad, then turn the bad sensor along with the diametrically opposite sensor and possibly test with the remaining two good sensors). Using three sensors (e.g. at 120 degree locations) is generally a bad idea since if one fails there is no way to salvage the data.

3.3.2 For Each Accelerometer: • Test each accelerometer by placing the 8G in accept mode and turning on the trigger selection for the accelerometer. Grasp the accelerometer block firmly between fingers and axially strike accelerometer with your hand on the end of the block opposite the wire and observe the velocity. Alternately impact the block on a firm surface. After the first impacts, the velocity should show a roughly straight signal line. • After the PDA triggers, the 8G unit digitizes the acceleration directly and integrates the signal to velocity. The software determines the acceleration zero level independently for each blow. • Make sure sensor selection includes both accelerometers (or all 4 if in 8 channel mode). If an accelerometer malfunctions during the test, usually it can just be turned off, and the test continued with the remaining good accelerometers. Because the velocities from different accelerometers are usually very similar, even in cases of extreme bending, the minimum acceptable number of working accelerometers for any test is one.

3.4 Calibration Pulse The Calibration Pulse checks the 8G Analyzer calibration. It does not check the calibration of the individual sensors. Details on the proper operation and interpretation of Calibration pulses are discussed in Section 5.3. The calibration pulse circuitry places a shunt resistor across the strain transducers to simulate a known strain and adds a known acceleration trace. The resulting velocity linearly ramps to the peak, then linearly ramps to a negative peak. It is recommended to record this signal for each test (or at least once per day). The peak amplitudes of these signals may vary and will, in general, not be equal as shown in Fig 3.1 (velocity is usually slightly higher than force). The calibration test confirms the sensors are working if square and triangular pulses are obtained. Note the calibration test signal using 8G transmitters and cables differ. Please see Section 5.3 on page 63 for additional cal test discussion and documentation.

Sensor Attachment: Calibration Pulse

25

Figure 3.1: Fig 3.1: Calibration Test with individual force records in the upper graph and individual velocity in the lower

3.5 Attaching PDA Bolt-On Sensors to the Pile • Fit the drill with the proper type and size bit and drill attachment holes in pile. All sensors made by Pile Dynamics, use 1/4-20 or M6 mm bolts. Strain transducer holes are 3 inches (76 mm) apart. Do not drill holes while standing in the leads. The weight of the 8G transmitters or main cable must also be supported on a bolt to the pile, preferably in a hole purposely drilled for such support. • For STEEL piles, drill 1/8” (3mm) pilot holes for sensors. For pipe piles, drill holes with 7/32” (5mm) bit and corresponding tap. For H-piles, use 5/16” (8mm) clearance holes. • For CONCRETE piles anchors are required. Drill holes with a hammer drill and 3/8” masonry bits for accelerometers and ONE HOLE for each strain transducer. Set anchors. Mount drilling template, drill the other strain transducer hole, set anchors. • With TIMBER piles, drill with 1/8” (3 mm) bit and attach sensors with lag bolts. • Attach sensors with proper type, size, and length of high strength bolts. If the bolt is too loose, the sensor may slip. When attaching to concrete anchors or when not drilling entirely through the walls of pipe piles, make sure the bolts do not bottom out on the anchors or bottom of the hole. Use extra washers or a shorter bolt to avoid bottoming out. Regular flat washers prevent scour of the sensors. Avoid lock washers. To prevent damage, attach sensors and use sensor protectors if attaching before lifting the pile, or attach sensors to pile after the pile is placed in the hammer leads.

Sensor Attachment: Attaching PDA Bolt-On Sensors to the Pile

26

*

Figure 3.2: Sensors, Connector Cable, Main Cable • When using a cable connection, attach sensors to pile connection cable and connect to main cable. Attach the main cable near the pile top to relieve tension in the individual sensor cables at the connections and reduce cable breakage problems. Do not attach cable to hammer leads or hammer. • When using wireless transmitters, the 8G transmitters should be supported by the pile through the rubber strap connected to the strain relief plate which is bolted to the pile. • Sensors may be attached at any pile location; measured energy decreases as attachment is made farther from top as some kinetic and strain energy remains in pile above sensors during the blow. The sensors should be attached to avoid end effects (1.5 diameters from top is a minimum although 2 or 3 diameters is preferred). The sensors should be above ground and above water at the final penetration to avoid sensor damage. For restrikes, sensors can be attached conveniently above the ground surface (about 4 ft or 1.2 m). For regularly reinforced (not prestressed) concrete piles, the sensors should always be attached near the pile top, where the pile has not experienced cracking. Avoid straddling a crack in a reinforced concrete pile or weld in a steel pile with the strain sensors. • During data collection, the PDA operator should always check data quality for consistency and proportionality and review warnings, as described in “Assessing Data Quality” on page 97. • If problems are suspected, check or replace sensors, connection cable and/or main cable or perhaps the 8G transmitter. The PDA will work with only one accelerometer if necessary provided the data from the remaining accelerometer is of high quality, consistent, and reasonable. • Two good strain sensors are required for reliable results. • Usually a problem is due to a bad sensor, connection to the pile or bad cable. Select a good sensor for trigger, and make sure sensors are firmly attached to the pile.

Sensor Attachment: Attaching PDA Bolt-On Sensors to the Pile

27

Please refer to Appendix C for sketches showing transducer bolt arrangement to different types of piles.

Sensor Attachment: Attaching PDA Bolt-On Sensors to the Pile

28

Sensor Attachment: Attaching PDA Bolt-On Sensors to the Pile

Chapter 4: File Setup

Figure 4.1: PDA-S desktop icon This Chapter discusses basic file set-up for data acquisition. Many data entry values require significant training in regards to the appropriate values entered for proper interpretation.

4.1 Starting the Program The 8G system will boot up to the desktop whereby the user may start the PDA-S

program by double clicking the icon. The PDA-S program has begun when the splash screen appears as shown below:

Figure 4.2: Splash Screen

File Setup: Starting the Program

30

4.2 The Title Screen

Figure 4.3: PDA-S Title Screen The PDA-S program opens to the Title Screen. Based on the user's installed owner file, the program will indicate the organization the unit is registered to and the serial number of the unit. The software version is also noted on this screen.

4.2.1 Review Previous Data Selecting the Review button opens the file explorer where the user may navigate to previous files and review data. Before proceeding into Data Collection or the configure WiFi screen the user should attach all sensors and cables to the main unit and power on any 8G transmitters.

File Setup: The Title Screen

31

4.2.2 About

Figure 4.4: The About Screen The About screen gives information regarding the program and owner file.

File Setup: The Title Screen

32

4.2.3 Configure WiFi

Figure 4.5: Transmitter pairing is set through the Configure WiFi Screen The Configure WiFi screen allows the user to register 8G wireless transmitters and determine which wireless transmitters the 8G system will be allowed to connect to. The ‘Registered Radios’ box identifies the 8G transmitters (radios) associated with your 8G hardware. A typical system may include more 8G transmitters than are typically necessary for standard tests. Therefore a user will highlight the desired 8G transmitter serial number under the 'Registered Radios' box ID’s and move them to the ‘Valid Radios for Connection’ box using the right arrow [>>>].

4.2.3.1 Adding a 8G Transmitter by Auto Discovery If the user is unable to identify which 8G transmitter is being used, turning on the ‘Discover Radios’ will automatically begin searching for potential valid 8G transmitters Once the list has been populated in the ‘Pending Radios’ box the user may select the desired 8G transmitter and hit the down arrow

▼.

4.2.3.2 Adding a 8G Transmitter by Direct Entry The user may add additional transmitters into the ‘Registered Radios’ box by typing the transmitter Serial Number into the ‘Register New Radio (Serial Number)’ Box and pressing the ‘Add Radio’ button. This will add the serial number of that transmitter to the ‘Registered Radios’ box.

4.2.3.3 Changing 8G Transmitters Should a transmitter sustain damage during driving or in some way become inoperable the user must close the data collection file and return to the configure WiFi button from the main screen. The user must remove the inoperable transmitter from the ‘Valid

File Setup: The Title Screen

33

Radios for Connection’ box by selecting the radio serial number and pressing the left arrow [ Save’.

8.3.2 Replay Factor Adjustments The Replay Factors can be similarly changed. Replay Factors adjust the magnitude of the sensor output. In general, there should be no reason to do this for good data and proper entry of parameters. Thus, a Replay Factor of 1.00 is standard and is desirable. Minor adjustments up to 2% or maybe 3% are sometimes used (e.g. factors 0.98 to 1.02), and are permitted since that is the basic sensor calibration accuracy. Changing to any other larger factor may not be justified. One exception is when an accelerometer is not axially aligned with the pile and its signal is then reduced by the cosine of the angle. The signal can be increased to restore the correct magnitude by entry of the inverse of the cosine into the replay factor. Replay factors are shown on the plots from PDA-S in brackets after the calibration constants for each sensor.

Data Adjustments: Changing Calibrations (or Replay Factors) in Existing Files

104

8.4 Drive Log Entry For cases where the length of penetration was not entered during a continuous pile installation, this information can be added later. This is accomplished by clicking the button in review mode or by clicking Edit in the Menu Bar followed by selecting Drive Log Data in the drop down menu. This brings up the dialog box shown in Figure 8.6.

Figure 8.6: The Drive Log Screen

8.4.1 Generate Drive Log From Parameters The first step is to select the “From Parameters” button and enter the final pile penetration depth in the “Transition Depth” box, the final penetration increment (LI) in the “Increment” box, and then select the add button. If the Increment value is consistent throughout the driving no further entry is required and pressing the OK button completes this process. If multiple penetration increments were used during the driving process, they can be added by entering the additional depth where the penetration increment changed in the Transition Depth box, the new penetration increment in the Increment box, followed by selecting the Add button. The depth and increment will then appear as illustrated in Figure 8.7. For example, a pile monitored only in blows per foot was driven to penetration (LP) of 77.4 ft from an initial penetration of 35 ft. First enter ‘Transition Depth’ of 77.4 and ‘Increment’ 0.4, and press ADD. Next enter ‘Transition Depth’ of 77.0 and ‘Increment’ 1.0, and press ADD. Then enter a ‘Transition Depth’ of 35 and a ‘Increment’ of 0 and press ADD (see Figure 8.7). Now press ‘OK’ and the entry form will be prepared for entry of the blow counts.

Data Adjustments: Drive Log Entry

105

Figure 8.7: Multiple length increments may be used The drive log table entries may be modified using the Update button or deleted using the Delete button. Note that a length increment of zero will terminate the drive log at the defined depth. After all transition depth and increment entries have been made select the OK button to create the drive log depths and penetration increments. An example of the completed driving log with blow counts entered is shown in Figure 8.8.

Figure 8.8: Once generated ‘From Parameters’ the drive log can be entered The next step is to enter the blow count into the “Blow Count” cells from the driving log in decreasing penetration order (blow count for last penetration depth entered first). Continue until the list is completely entered. Note that the cell information for Blow Number, Blows/depth unit (e.g. bl/ft), and Set/ Blow are then automatically calculated and entered purely from the blow count and depth entries.

Data Adjustments: Drive Log Entry

106

If an error was made in data entry then the blow count record will be shifted up or down from the depth column. To correct this if (when) it occurs, place the highlight on the depth where the error occurs and click to highlight. Then click on the Insert Blow Count or Remove Blow Count buttons to shift the data entries at and below that location up or down relative to the depth column. If inserting, then enter the new value in the blank cell generated. The ground reference elevation can be entered and the pile bottom elevation (EL) is then calculated. If the pile is not driven vertically, also enter the horizontal and vertical values for the inclination (e.g. 1 horizontal for 6 vertical), and the angle of installation from vertical will be computed and the bottom elevations adjusted appropriately. When completely finished and satisfied, click Apply and then OK to accept your entries. The LP values and set per blow for each blow number will then be adjusted to the corresponding values as per the table created above.

8.4.2 Generate Drive Log From LP Values

Figure 8.9: Drive log can be auto-populated from manual entries with the ‘From LP Values'’ button In instances where the field user utilized the button during field data collection, PDA-S can use that information to auto-populate the drive log for editing and manipulation. This assigns penetrations for each blow based on field observations, yet can correct possible errors. The displacement curve is then adjusted to match the final observed sets calculated from the blow count entries. t.

Data Adjustments: Drive Log Entry

107

These entries will be retained permanently with the data when the file is then saved again. Requesting the drive log again will bring the previous entries into view for editing, if needed. If you press Cancel (or ESC), nothing will be retained from your effort.

8.5 Blow Number Adjustments 8.5.1 Incrementing the BN or LP Clicking EDIT / INCREMENT (BN/LP) will request a dialog box allowing you to edit the blow numbers (BN) or penetration depth (LP) by some user entered value for all blows or some subset of blows. If, for example, LP was incremented in the field data acquisition but missed for one increment (so that increment has about twice as many blows as it should have), then go to the blow where the increment change was probably missed and request the Increment LP function, enter the value of one length increment, and answer to apply only to blows from current to end of file. If the reference was changed, you can adjust all LP values by answering apply to entire file.

8.5.2 BN/Energy Filter Clicking Edit from the Menu Bar followed by Blow Number Filter in the drop down menu will give a dialog box allowing you to edit systematic blow rate and energy and thus blow counting errors.

8.5.2.1 BN Filter

Figure 8.10: BN Filter (Example Ex-56) A graph shows the blows per minute (BPM) versus BN for all blows (first blow in file at bottom; placing the cursor on the data point will reveal the BN and the BPM for that blow). •

If the BPM is too high due to a bounce blow, entry of a reasonable MAXIMUM BPM less than the value in error will cause that blow to be eliminated from the data set (blow will be eliminated and the BN values resequenced).

•

If a blow was missed during data collection such that the BPM for that one blow is about half the BPM for surrounding blows (or 1/3, or 1/4), enter reasonable values for both

Data Adjustments: Blow Number Adjustments

108

allowable MAXIMUM and MINIMUM BPM (you can click on the graph itself or enter in the dialog value entry boxes). If double or triple or quadruple the low BPM result then places the computed BPM within these limits, then the BPM is corrected and the BN adjusted to indicate a blow(s) was missed (skip one, or more, BN’s and add one or more to all subsequent BN’s in the file). When the limits are considered correct, press APPLY to activate the corrections. This function may only work correctly on the original data where each and every blow was saved (e.g. the BN are sequential with no skips). Thus, this function should be run BEFORE deleting any blows either individually or using the EDIT/SQUEEZE function. Note that the BN values will be corrected, but it will not recreate the force and velocity data for the missing blows. In case the maximum blow rate is set too low (e.g. MB set to 60 for a hammer running at 90 BPM), only every other blow will be acquired and will be labeled sequentially with an incorrect BPM (e.g. 45 instead of 90). For this example, to correct the BPM and BN values, entering a Maximum BPM of about 100, and a Minimum BPM of about 80, should correct the data to restore the right BPM and BN. However, as soon as it is noticed, the maximum value should be set to a speed slightly higher than the anticipated maximum blow rate.

8.5.2.2 Energy Filter

Figure 8.11: Energy Filter (Example Ex-56) In cases where multiple hammer shut down blows are recorded or bounce blows for drop hammers, the user may apply an energy filter to remove such blows. The user may select a minimum or maximum threshold based on energy. If the energy for a particular blow is too low due to a bounce blow or hammer shut down, entry of a reasonable minimum energy greater than the low energy impacts will cause that blow to be eliminated from the data set. The blow will be eliminated and the BN values resequenced.

8.6 Modifying Project/Pile Parameters The original information in a file may be in error. For example the length could be wrong, or even the pile name could be in error. You can change these global parameters (which generally apply to all blows of the current file) with the two-letter input commands (e.g. ‘pnTest Pile’ [Enter] would change the pile name to ‘Test Pile’). The new

Data Adjustments: Modifying Project/Pile Parameters

109

parameters will be used then for further processing as long as this file is open. These parameters can be permanently retained only by saving the file again. The overall wavespeed (WC) can be changed for each blow independently (See “Variable Wavespeed WC Values” on page 129.). The displayed precision of any variable (e.g. AR, LE) is selected in the Output Quantities menu (Section 7.1.2). Clicking on the appropriate Category name shows a list of variables affected by that selection. The user can then change the precision (number of significant digits to the right of the decimal point).

8.6.1 Modification to Project Information The following parameters entered during File Setup can later be changed with the twoletter input command method (entry of the two letters followed by either numerical value or an alpha-numeric label). Documentation related commands: •

PN - Pile name

•

PJ - Project name

•

PD - Description of pile or hammer or soil

•

PC - Print a comment in result file (each blow can have one separate comment)

•

OP - Operator Name

8.6.2 Modification to Pile Parameters Pile properties related commands - Note than when adjusting these commands the program will first ask what blows the change will affect, and then display the pile information screen and require the user to verify selection. •

AR - Area

•

LE - Length below sensors to pile bottom

•

SP - Specific weight

•

WS - Wavespeed (used to calculate EM)

•

WC - Wavespeed Calculated ( WC used only for 2L/C TIME; WC < WS)

•

EM - Elastic Modulus ("EM" is automatically calculated from SP and WS, or WS from EM and SP)

•

JC - Case Damping Factor

•

LP - Length of Penetration (M or FT ) (can only be directly entered during active data collection)

•

LI - Length Increment (M or FT ) (use remote blow switch or

to increment LP by LI)

Data Adjustments: Modifying Project/Pile Parameters

110

8.6.3 Multiple Pile Profiles Some files may have variable pile lengths, or other changed variables. This might occur either during data collection when a pile is spliced, or perhaps by merging files together (Section 8.10.1) (e.g. merging the second section of a pile after splice to the end of the driving of the first section). In that case, changing the LE will affect only the blows matching the current LE for that blow.

8.6.3.1 Pile Profiles When a user defines the pile parameters during file set-up they are translated into a ‘Pile Profile’. All data collected references a specific ‘Pile Profile’. Updates may be made to the Pile Profile during data acquisition, but these updates are limited. Changes will either affect ‘All Data’ (data already collected and data to be collected), or it will affect new data only (data collected from that blow forward). If the changes are applied to new data only, a second (or additional) pile profile will have been created for that file.

8.6.3.2 Editing Pile Profiles While in review mode, modifications may be made by clicking in the Pile Information pane in order to bring up the Pile Information form. A preliminary screen is displayed that summarize the Pile Profiles associated with the current file. For each Pile Profile, a summary of the pile material properties and dimensional properties will be displayed, as well as the range of records (SL) associated with each Pile Profile. If penetration information has been entered, a summary of the penetration range for a Pile Profile will be listed as well. Note that the Pile Profile associated with the current record (storage location) is highlighted with a black border.

Figure 8.12: The Pile Profile screen is prompted when adjusting pile information

Data Adjustments: Modifying Project/Pile Parameters

111

Pile Profiles may be modified by selecting Pile Profiles (noted by a black outline) and select the range of blows (SL) the modifications will be applied to. The buttons at the bottom of the window detail the range of records that will be affected if the button is selected. If another Pile Profile with adjacent blow numbers above or below the initially selected profile is selected, the range of records will be updated to include the second Pile Profile. If non-contiguous Pile Profiles are selected, the update options will be limited. Updates may also be applied to the Current Record only. Once the desired Range is selected, the Pile Information window will be displayed. Note that the range of records matches the range selected by the user.

8.7 Radio Adjustments 8.7.1 Radio Data Re-Alignment 8G data from multiple independent wireless channels must be aligned in time to remove potential phase shifts (if the radio transmitters are linked by a physical cable, then their triggering is automatically aligned and this shifting is not needed). Extra data is captured by the 8G so that one set of signals can be shifted in time relative to the other if necessary. The PDA 8G unit does this during data acquisition. This alignment can be reviewed or adjusted using the WiFi Menu in the upper right section of the screen and selecting ‘WiFi Align’ which will result in the Radio Data Alignment window depicted in Figure 8.13 to appear.

Figure 8.13: Radio Alignment Screen In this window the user may choose to align the data automatically or manually. To automatically align wireless data, the user can select the Trigger, Accel, or Force button

Data Adjustments: Radio Adjustments

112

in the 'Align On' column and the 8G will automatically align the data using the selected trigger channels, acceleration data, or force records, respectively. The option for manual alignment can be activated by clicking on the Select button in the 'Align On' column. Select - gives more control over which sensor combination will control the alignment (e.g. the phase shift between transmitters). For example, this is helpful in case of one bad accelerometer so that the alignment will use some sensor combination that excludes that bad accelerometer). The Normalize and Differentiate buttons are highly recommended to be active (indicated by the button turning dark gray) although in some alignment methods these algorithms are not used. In most data cases it is strongly recommended that the 'Alignment Method' be selected as Convolution 7 in the underlying drop down menu. Pressing the 'Align Current' or 'Align All' button will analyze the current blow or all blows (each blow is independently evaluated), respectively. The user can use the slide bars above the data display window to individually adjust alignment (although this is almost never needed with the Convolution 7 method). The alignment is shown in the data display window. The adjustment may be applied to each blow individually.

8.7.2 Wireless Synchronization Correction

Figure 8.14: Wireless Synchronization Menu Sometimes when collecting data with the 8G using transmitters you may notice two consecutive records.These records will have the same date/time stamp, and that one record is showing a force and velocity trace equal to zero, whereas the other record is showing the other force and velocity traces equal to zero. This is an indication that the two records in fact correspond to the same blow, but that due to lack of synchronization the signals from the two radios were perceived as two different blows by the 8G.

Data Adjustments: Radio Adjustments

113

Another indication of the occurrence of this problem would be a sudden drop of the average force and velocity data to about half the normal value on two consecutive blows compared with previous and subsequent blows.

The PDA-S program on the 8G has a function accessible from the WiFi Menu capable of fixing this problem in most cases. In order to access this function, go to Review Mode and Select the file in question, and then click on the ‘Sync’ button. The system will attempt to recombine all records within 2 seconds of each other. The user then has the ability to remove all ‘uncombined records’ by clicking the “Hide Rogue Records” button. The files may be recovered by clicking the ‘Hide Rogue Records’ once again or by clicking the ‘Sync’ button and then pressing ‘Done’.

8.8 Changing Hammer Properties

Figure 8.15: Hammer Properties Menu If the hammer was improperly entered during data acquisition (or not entered and now desired to be entered), select 'Edit' on the Menu Bar and then ‘Hammer Properties’ in the drop down menu. The Hammer Properties window displayed in Figure 8.15 will appear. Clicking on the ‘Hammer from List’ button will bring up the entire database of hammers to allow selection as described in “Hammer Selection Screen” on page 48.

8.9 Preparing files for CAPWAP Analysis CAPWAP adjustments - The velocity of any individual blow may be changed to add acceleration over selected portions of the velocity curve resulting in a match of final displacement to a user input set per blow. Set is the final net penetration per blow which should match the visual observation of net permanent pile displacement (set) per blow; the user input 'Set' value will change the blow count or input of 'Blow Count' (e.g. in the CAPWAP Adjust window or in the PDA-S DRIVE LOG) will update the set. The set value entered will be displayed on all displacement versus time graphs so the user can assess the impact of any adjustment. The goal is for the user to make the displacement as a function of time to be as reasonable and realistic as practical. Normally this should result in a horizontal end of the displacement curve that matches the set per blow.

Data Adjustments: Changing Hammer Properties

114

8.9.1 CAPWAP Preparation The CAPWAP adjust analysis.

button accessed from the

prepares the data for CAPWAP

Figure 8.16: The CAPWAP Adjustment window prepares files for CAPWAP Analysis For the CAPWAP program, the PDA-S program makes the CAPWAP data adjustments as described in the CAPWAP manual (A12, A34, AC etc.). The data adjustments to produce a reasonable displacement versus time function with the correct set per blow are further described in Section 8.9.1.1. The data adjustments made will be included and saved in this file. The entry of LP (depth or length of penetration into the soil), Circumference and Bottom Area (please watch dimensions) are input parameters only needed in the CAPWAP analysis and should be completed for reference (Circumference and Bottom Area are automatically generated by the area calculator function). The Blow Count and/or Set should be entered. Set is the observed net final permanent penetration per blow, and can be compared with the final displacement, DFN, at the designated data point defined by the “@” entry box (default value is the last data point). If the DRIVE LOG feature was used the Blow Count and Set will be will be entered automatically.

8.9.1.1 Final Displacement Correction Clicking ‘Defaults’ will set the times (T1, T2, TC, etc.) and adjust the acceleration adjustments (A12, A34, AC) so that the final set DFN is equal to the observed or user entered set per blow. The user may adjust the Set or any of the acceleration (except AC) and time parameters and the program will automatically adjust AC making the final displacement equal to the entered Set. If the displacement curve still needs adjustment (after the Default input), the general recommendation is to first change the A34 value. The velocity adjustments can be removed by clicking the ‘Remove from current record’ button for a particular blow or ‘Remove from all records’ for the entire file.

Data Adjustments: Preparing files for CAPWAP Analysis

115

8.10 File Modifications 8.10.1 Merging Files If a file is open, another file can be appended to it using the ‘File / Merge’ function. The files selected from the merge function will be appended after the existing record. This is useful if a pile is spliced, or if a restrike is desired to be appended to the driving blows. The merge function will merge files of varying sampling frequencies, time intervals, or gage selection. After merging, the user may store the merged files in the standard save methods, and it is best to rename the new file so the original data is maintained. Keep in mind the user should merge files such that the length of penetration (LP) and time increments are sequentially increasing. This function requires careful thought and correct application by the user.

8.10.2 Hide/View Cal Records The Record Management features in the Options menu allow users to exclude Calibration Pulses from analysis and reporting without removing them from the data file..Generally it is recommended for the user to select ‘Auto Adjust as Required’. For information regarding calibration pulses See “Calibration Check” on page 63.

8.10.3 Deleting Blows Individual blows of data of insufficient quality may be deleted from a file by displaying the blow to be deleted and then selecting 'Edit' from the Menu Bar followed by 'Delete Current Record' in the drop down menu. Alternatively a record can be deleted by entering [Ctrl]+[Del] concurrently on a keyboard.

8.10.4 Reducing Data Files There is no limit to the number of blows in a ‘.pda’ file. The only limit is the available hard disk space. However, hundreds or thousands of blows creates very large files which are difficult to transfer to another PC or store for archive purposes. In a large sequence of blows, often one blow is similar to the next and changes occur rather gradually. Thus, a sample of the data is often sufficient for archive purposes.

Figure 8.17: The squeeze feature allows a user to reduce file size.

Data Adjustments: File Modifications

116

To produce a sample which automatically reduces the file size, click ‘File' from the Menu Bar followed by 'Squeeze' on the drop down menu. Of course, some data is more important than other data. For example, the first blows of a restrike are more important than later blows, or the end of driving blows are more important than the early blows. Using the entry boxes in the Squeeze window, you can select the 'First Location' to start saving records by entering the first record SL value as well as the 'Last Location' by entering the ending record SL value. In addition, the number of blows to consecutively 'Save at Beginning' and 'Save at End, as well as the 'Save Frequency' of blows in between. Increasing the save frequency value reduces the total blows saved. Prior to taking this step, it is recommended to check the BN Filter (“BN/Energy Filter ” on page 107) to first correct any problems, since BN Filter only works properly when ALL blows are present. The blow numbers can be renumbered based on the value assigned to the 'First Blow Number' in the dialog box. Subsequent blow numbers will be adjusted by the difference between the first blow’s current and new entry blow numbers. Once a file is reduced, some blows will be removed permanently. If you want to create multiple files from the same original data, such as a sequence of blows in the middle of the testing, copy and re-label the file using a different name prior to reducing the original file or save the reduced file under a different file name.

8.10.5 Exporting FIles to ‘.w01’ Format The user may downgrade a ‘.pda’ file into a ‘.w01’ from the File menu by selecting ‘Save As W01’. When selected a w01 file of the same name will be created in the same directory. Please note that there are significant limitations to exporting files into the w01 format. •

The configuration of gages should attempt to match configurations used in the w01 file format.

•

8G data collection is based on sample time; PAX/PAK data collection is based on point count. Therefore the PDA-S program will repeat the last data point, which should be effectively zero anyway, to fulfill the required number of data points for the w01 format.

It is strongly recommended that the user confirm the data’s integrity before proceeding with data analysis, reporting or submittal.

Data Adjustments: File Modifications

117

8.10.6 Display of Multiple Data Files Simultaneously

Figure 8.18: Comparisons between two pda files may be useful for observing set-up, relaxation, hammer performance, etc. More than one set of data can be viewed at the same time. This would allow for example the end of drive data to be directly compared with the restrike data of the same pile, or results of one pile compared with those of a second pile or and earlier blow with a later blow from the same sequence. To use this feature, select 'Windows' from the Menu Bar followed by 'Tile Vertical' from the drop down menu. Click on any of the open documents to make that the active window. Shrink or expand any window by a drag and drop technique on any boundary.

8.11 Saving Data As the signal of each sensor is digitized, the data is also stored as separate signals (i.e., A1, F2, F3, A4). After testing is complete or data is reprocessed, data is permanently saved in a file by selecting 'File' from the Menu Bar followed by 'Save' or ‘Save As’ in the drop down menu. ‘The ‘*.pda’ file created (file name will be generated from the PILE NAME with a ‘.pda’ extension) can be placed in any folder. It is good practice to keep all piles tested in a job-site folder that you create for each project (the PDA-S creates a job folder based on the PROJECT name). File size will vary based on number of blows, time duration selection and frequency selection. The PDA-S program will read any data created by an 8G system and will be able to convert existing ‘.w01’ files into the current '*.pda' file format. Files may be exported into the ‘.w01’ format described under Section 8.10.5. If changes are made to an existing data file (active sensors, calibrations, LP driving logs, reduced file size by eliminating excessive blows, CAPWAP adjustments, added comments, changed names or hammer information, etc), the data file must be saved

Data Adjustments: Saving Data

118

again to retain the changes made. Saving the reprocessed data in a new file name will retain the original data file (although usually the reprocessed data is saved to the original file name.) A new folder can be created prior to the test using Windows Explorer (right click in any area and then with NEW, select FOLDER, and then name the folder preferably with the project name). You can create a folder even after the data is acquired by selecting 'File' from the Menu Bar followed by 'Save As' from the drop down menu. This will bring up the Save As dialog box. Right click in the large window showing the files, and select NEW, select FOLDER, and rename the new folder. If power is interrupted before the data file has been saved, a provision in the program provides for a backup file. If an unsaved backup file exists when you restart the program, a prompt asks if you want to save the file. This is your one and only opportunity to recover lost data.

Data Adjustments: Saving Data

Chapter 9: Output 9.1 Creating Output files The user is able to create output graphs for individual records using three options: the HP output view, pdf report generator, and bitmap generator.

9.1.1 Reports Several auto-generated reports may be created by clicking the button in data review mode or by selecting ‘Report’ from the ‘Functions’ menu. The ‘Report Setup’ screen will appear allowing the user to select one of nine report options.

Figure 9.1: the Report setup for reports

Output: Creating Output files

120

Several plots can be made with a semicolon showing a single axis group based on combinations of the following: •

The Average Force and Velocity curves

•

The Average Displacement and Wave Down curves

•

The Wave Up and Wave Down Curves

•

The Static Resistance (includes JC) and Totoal Resistance (JC=0).

•

The Average Energy and Displacement curves

•

Individual Force curves

•

Individual Velocity curves

•

The iCAP Force vs. Length of Pile Curve

•

The iCAP Force Match Curve

9.1.1.1 Printer Options When the program starts, the default printer that is presented to the user is the default printer selected within Windows. When changed in the PDA-S Application, it remains changed for the PDA-S application until the application is closed. It will not affect the global default printer settings.

9.1.1.2 Report Options The ‘Report Options’ menu give choices on the following: •

Include Target Capacity - will note the target at the top of any resistance graph when enabled

The user may copy the plot from the ‘Functions’ menu and selecting ‘Copy to Clipboard’. The image may then be pasted into a document for printing and reporting.

9.1.1.3 General Options Return to Setup Form - allows the user to return to the Report Setup when Print Preview is closed.

9.1.1.4 Generating a Report Once the user has defined the desired graphs and reporting options a report can be generated by clicking the ‘View’ button. The program will then generate a report and open a new window.

Output: Creating Output files

121

Figure 9.2: Report Print Preview The user may copy an image of the report to the clipboard that may then be pasted into a document for reporting purposes. The user may also print the file by clicking on the printer icon. Once a user selects one of the predefined reports it will be immediately generated and open in print preview.

9.1.2 Legacy “HP” Reports Once a user has navigated to the blow they would like to create an output for, the Report View may be activated by selecting from the ‘Functions’ menu bar and then ‘Legacy “HP” Reports’. The ‘Report Setup’ screen will appear allowing the user to select one of twelve graph options.

Output: Creating Output files

122

Figure 9.3: the Report setup for Legacy “HP” reports Several plots can be made with [ ] braces showing a single axis group based on combinations of the following: •

[F,V ] - Force, Velocity

•

[ WD,WU] - Wave Down, Wave Up

•

[RS,RT ] - Resistance Static (includes JC), Resistance Total (JC=0)

•

[RS,RT 3JC] - Resistance Static (includes JC), Resistance Total (JC=0), The Static Resistance based on

±50% of the current JC value.

•

[E,D] - Energy, Displacement

•

[E,EF2,D] - Energy, Energy Based on Force Solely, Displacement

•

[Ind F] - Individual Force curves

•

[Ind V ] - Individual Velocity curves

•

[Ind D] - Individual Displacement curves

9.1.2.1 Printer Options When the program starts, the default printer that is presented to the user is the default printer selected within Windows. When changed in the PDA-S Application, it remains changed for the PDA-S application until the application is closed. It will not affect the global default printer settings.

9.1.2.2 Report Options The ‘Report Options’ menu give choices on the following: •

Black on White Graph - creates a report with a white background and black traces.

•

Include Scales and Pile - plots tick marks for each 25% of the maximum scale for each graph. Additionally, includes a representation of the pile below the top graph.

•

Include Target Capacity - will note the target at the top of any resistance graph when enabled

The user may copy the plot from the ‘Functions’ menu and selecting ‘Copy to Clipboard’. The image may then be pasted into a document for printing and reporting.

Output: Creating Output files

123

9.1.2.3 General Options Return to Setup Form - allows the user to return to the Report Setup when the Print Preview is closed.

9.1.3 Generating a Legacy “HP” Report Once the user has defined the desire graphs and reporting options a report can be generated by clicking the ‘View’ button. The program will then generate a report and open a new window.

Figure 9.4: Legacy Report Print Preview The user may copy an image of the report to the clipboard that may then be pasted into a document for reporting purposes. The user may also print the file by clicking on the printer icon.

9.1.4 Creating Bitmap Output If a simple bitmap of a specific graph is required, the user may generate those bitmaps by selecting ‘Generate Bitmaps’ through the ‘Functions’ menu in the Menu Bar, or the user can select the button from the submenu in the Operations Toolbar. This action will create a sub-folder in the file’s directory with bitmaps of the currently displayed graphs.

Output: Creating Output files

124

9.2 Copy Data to Clipboard Data can be exported to spreadsheets using the ‘Functions > Copy to Clipboard’ option on the menu bar. The data itself (rather than graphics image under normal Print Screen copy) is then available on the clipboard. It can then be pasted into any spreadsheet for further computation and specialized plots.

9.3 Creating ‘SQ’ File A text file of all current output quantities for all blows may be created through the ‘SQ’ file option. This may then be imported into a spreadsheet program for graphing and analysis. To create the ‘SQ’ file the user selects the ‘Create SQ file’ from the ‘Functions’ menu.

9.4 Exporting files to PDIPlot2 Once files have been properly adjusted the files may be saved and loaded into the PDIPlot2 program. The user will start in the PDIPlot2 program and select the desired file to import from PDA-S. Details regarding operation of PDIPlot2 are located in the PDIPlot2 manual.

9.5 Importing records from PDA-S into CAPWAP® Files may be imported into CAPWAP ® for signal matching analysis to determine bearing capacity, resistance distribution, damping selection, stress calculation and non-uniform pile modeling. Details regarding file preparation are discussed in “ Preparing files for CAPWAP Analysis” on page 113. Further information regarding CAPWAP analysis and the CAPWAP program is included in the CAPWAP manual.

Output: Copy Data to Clipboard

Chapter 10: Material Property Selection 10.1 Specific Weight Density (SP) The Specific Weight Density (SP) of the pile material can be defined as it’s weight per unit volume. It is expressed in kips/ft 3 (English), Ton/m 3 (Metric), or KN/m 3 (SI). Typical values of densities for steel, concrete and timber are given in Table 10.1. Most materials have variable densities. For example, cast iron and grout (as used for certain CFA or auger-cast piles) have lower densities than steel and concrete, respectively. The greatest variability exists for timber and plastic materials. In any event, the PDA test engineer has the responsibility to ensure that the correct density values are used. This is critical since the elastic modulus is proportional to the material density. For timber or plastic a simple weighing test of a sample taken from the test pile is part of good PDA testing practice.

10.2 Wave Speed (WS) The Wave Speed (WS) is defined as the speed of the compression or tension wave traveling through the pile. It can be expressed in either ft/s (English) or in m/s (Metric or SI). Expected wavespeeds for steel, concrete and timber piles are given in Table 10.1. However, the wavespeed for concrete or timber is variable and should be determined for each pile on an individual basis. Note that WS may be variable along the pile length. In that case WS must be the wave speed at the point of measurement where the strain sensors are mounted. WS is used to calculate a default value for the elastic modulus EM.

10.3 Elastic Modulus (EM) The Elastic Modulus (EM) of the pile is defined as the slope of the stress-strain curve in the elastic region, and measures the objects resistance to be deformed. It is expressed in ksi (English), Ton/cm 2 (Metric) or MPa (SI). Common values of elastic moduli for steel, concrete and timber piles are listed in Table 10.1.

Material Property Selection: Specific Weight Density (SP)

126

10.4 Relationship between Pile Properties For an elastic pile, the wavespeed, modulus and density are related by EM = c

2

2 SP =  -------  WS   g

where ‘’ is the mass density, ‘c’ is the wavespeed, and ‘g’ is the gravitational constant (32.2 ft/s 2 or 9.81 m/s 2 ) and dimension conversions are required to obtain the modulus in it’s correct units. The PDA-S program assures the theoretical relationship for EM, WS and SP. If any of the three variables are changed, the corresponding complimentary variable is automatically changed (Changing EM changes WS; Changing WS or SP changes EM). For example if WS is measured at 4000 m/sec and the density is assumed to be 2.45 Ton/m 3 , then the elastic modulus will be computed automatically to be 400 Ton/cm 2 .

Table 10.1: Typical Pile Material Properties * Variable

EM

SP

Steel

Concrete

Timber

30,000 ksi

5,000 ksi

2,000 ksi

2,100 Ton/cm2

360 Ton/cm2

160 Ton/cm2

206,843 MPa

35,000 MPa

16,000 MPa

0.492 k/ft3

0.150 k/ft3

0.060 k/ft3

7.85 Ton/m3

2.45 Ton/m3

1.0 Ton/m3

77.3 KN/m3

24.0 KN/m3

10.0 KN/m3

16,800 ft/s

12,400 ft/s

12,400 ft/s

5,123 m/s

3,800 m/s

3,960 m/s

WS, WC

* Please note that all properties must be accurately determined on site

10.5 Pile Impedance The pile impedance ‘Z’ is calculated using the following equations: AR Z =  EM  -------- = AR  EM   = AR  WS   WS where  = SP ------g The quantities ‘EM’, ‘AR’ and ‘SP’ used in the above equations are measured at the sensor location and defined in the previous sections of this chapter. The units of ‘Z’ are kip-s/ft (English), Ton-s/m (Metric) and kN-s/m (SI)

Material Property Selection: Relationship between Pile Properties

127

10.6 Computation of ‘SP’ and ‘EM’ for Composite Piles For a steel pipe pile filled with concrete, initial values can be computed from the weighted average unit density ‘ SP ’ and the weighted average modulus ‘ EM ’ (using some initially assumed concrete modulus).  AR S  SP S  +  AR c  SPc  SP Composite = -------------------------------------------------------------------- ARs + ARc   AR S  EM S  +  AR c  EM c  EM Composite = ------------------------------------------------------------------------- AR S + AR c  where the subscripts ‘ S ’ and ‘ c ’ refer to steel and concrete respectively. Entering these weighted averages as a PDA input will yield an initial estimated wavespeed (estimated because the concrete modulus was estimated). If the testing suggests a different wavespeed, enter the suggested wavespeed and the modulus will be adjusted; the weighted average density is usually a much better estimate than the weighted average modulus. Of course, the above formulas can also be used to back calculate the elastic modulus for the concrete from the corrected composite value of EM . EM Composite  AR S + ARc  –  AR S  EM S  EM c = --------------------------------------------------------------------------------------------------------- AR c  Note: For composite concrete filled steel pipes, the concrete should be filled to the top of the steel, and even slightly crowned, to assure good bond between the concrete and steel during impact. Use a plywood pile top cushion to protect the top concrete surface during impact.

10.7 Determination of Wave Speed Pile wave speed WS (and modulus EM) must be accurate for correct evaluation of the measured signals. As mentioned earlier, the wave speed in steel is approximately 16,807 ft/sec (5123 m/sec). The wave speed for concrete and timber must be determined for each pile. Choosing the wrong wave speed results in force, stress, energy and capacity calculation errors. Thus proper wavespeed determination is critical to successful dynamic pile testing.

10.7.1 During Driving If Wave Up indicates some tension reflection (local "valley" in Wave Up at 2L/C), wave speed determination is possible. Records during easy driving (e.g. low blow counts, or high set per blow) are best, because the tension return from the pile toe is most obvious. Investigate the WD and WU screen display shown in Fig 7.1.

Material Property Selection: Computation of ‘SP’ and ‘EM’ for Composite Piles

128

Time Marker B Time Marker A

Figure 10.1: Wavespeed inspection from the Force Wave Up (WU) Curve Use the correct length below sensors (LE). The first dashed rise time marker is automatically positioned at time A by PDA-S; shift the second dashed rise time marker (using left and right arrows) to the time B (the beginning of the Wave Up valley at 2L/C). Time marker A is program selected and cannot be changed. If you would like to select another rise time, then shift the T1 marker using the INS and DEL keys. (When done with the wave speed determination restore the T1 marker to the peak using the DL0 command). Use the Left and right arrow keys (either on the keyboard or from the Sub -Menu) to adjust the time B and T2 markers. The PDA calculates the computed wave speed WC from the time difference between the two time markers and LE; enter this value into WS. •

In hard driving, the Wave Up valley may not be apparent. Instead the Wave Up curve may increase sharply a short time before or after the “B” time. It is tempting to use this information to calculate WS; however that may not be accurate enough because the wave-up increase is a function of the soil stiffness near the pile toe and not a function of the pile properties.

•

Instead of using the time of Wave Up increase in the beginning and the later Wave Up slope inflection from a tensile response from the pile toe, the corresponding peak velocity values are sometimes used (e.g. peak input to minimum in the “2L/c valley”). In very easy driving, this works well if and only if the shape of the wave up is very similar to the shape of the wave down.

•

Even though the wave speed has been set correctly, the peak markers T1 and T2 do not necessarily align with the initial peak and the reflected valley. This may happen, for example, when the resistance is moderate, or the pile has minor tension cracking. The T1 and T2 markers will only be aligned with the initial peak and the corresponding valley if there is a very easy driving condition (large set per blow) and the Wave Up shape (and duration) at 2L/c mirrors the Wave Down shape (and duration) at the initial peak.

Material Property Selection: Determination of Wave Speed

129

10.7.2 By Proportionality Calculation If the sensors are attached to the pile at a location far above ground location, and if the pile is uniform, then force and velocity should be perfectly proportional at the first peak, EA v t1 -------- = F t1 . If the ratio  Zv t1   F t1 is not equal to 1 then multiplying WS with this ratio c should yield a better estimate of WS. It is always preferable however, to use the wave return for wave speed determination.

10.7.3 By Wave Up Inspection In any case, and even for diesel hammers, the wave up curve should be smooth through the peak velocity input time for uniform piles. There should be no steps or jumps through the period of time from the initial rise to the peak input. If the Wave Up is too low at this time (local step decrease), then the WS is probably too low. If the wave up is too high (local step increase), then WS is probably too high. Also, phase shifts should be minimized (eliminated) using VT prior to assessing the wave up curve.

10.8 Variable Wavespeed WC Values Review of “Determination of Wave Speed” on page 127 is highly recommended for those testing concrete or timber piles. There may be occasions where the overall wavespeed for the entire pile length is not consistent with the modulus and density at the transducer location and the user has been therefore given the flexibility to input separate values. Although direct input is not allowed, the Wave Speed calculated (WC) from the input length LE and the T1 and T2 time indicator marks is easily adjusted by the left and right arrow cursor keys on the keyboard or from the left and right arrows in the Submenu. The WC value is often equal to or less than WS. For example, the overall wavespeed of concrete piles may be slowed due to minor cracking; WC significantly faster than elastic solution wavespeed WS should only be used with caution for uniform driven piles. WC may differ slightly from WS due to the discrete sampling frequency. WC is used only for the 2L/c computation and does NOT affect the relationship between WS, SP and EM and therefore does not affect the calculated force or the force dependent quantities. WC might be faster than WS for multi-section spliced concrete piles where the top section has lower strength and lower wavespeed than a previously driven segment, or where the sensors are attached to the concrete in a composite pile with a concrete top section with a protruding long steel H pile at the bottom. In the case of concrete piles, the overall wavespeed may vary progressively (gradually get lower) during the driving of one pile due to minor tension cracking or joint related phenomena. In this case the user should use the rise-to-rise method to determine the overall wavespeed (WC) used in the Case Method capacity computations. In practice, WC wavespeed is almost always highest at the beginning of each data set, therefore determine the highest WC and make sure it is entered for the first blow (and WS set to this value).

Material Property Selection: Variable Wavespeed WC Values

130

If as is often the case for uniform driven piles, WC is higher for earlier blows and changes gradually to a lower value at the end of driving, the PDA-S offers a convenient means of WC adjustment in ‘OPTIONS > Calculated Wavespeed’ on the Menu Bar. There are three choices:

10.8.1 Constant for Pile means any change in wavespeed caused by left or right arrow keys will change effective wavespeed WC of every blow.

10.8.2 Blow by Blow Auto Edit In Auto Edit mode, the user should start at the first blow of the data set with the assumed correct WC at the beginning of the data set (and correct WS). Each time a subsequent blow is accessed, the program proceeds to the next blow and assigns that blow the same WC as the previous blow. The user continues advancing through the data file until an adjustment is needed in WC; the adjustment is made on any blow with the left and right arrow keys prior to proceeding to the next blow. The user continues through the entire data set making adjustment when necessary as the WC gradually slows (or in rare cases increases). When the WC has been properly adjusted for every blow, the file should be saved to retain these values for future use. For files with variable wavespeed, after the WC has been adjusted for all blows in this “auto” mode, the wavespeed calculation method should be changed to the “blow by blow edit” mode to prevent further accidental changes.

10.8.3 Blow by Blow Edit In Blow by Blow editing each blow can be independently adjusted by the left and right arrow keys. This option will be rarely needed for data entry except for perhaps files with only a very limited number of blows. It is highly recommended this method is used after the “Blow by Blow Auto Edit” to keep the variable WC without further changes.

10.8.4 Use of LS to determine appropriate WC While not exactly a WC function, the LS function (Length to Splice) can be used to help locate splices in a jointed concrete pile (if a tension reflection from the splice can be observed). The LS and WC functions can then be used to perhaps help determine WC for specific pile sections. The LS value can be entered by the user and a vertical line will appear at this depth (below sensors) on the graph (at time 2*LS/WC after the initial rise marker). Entering Splice values is described in Section 4.3.3.4.

Material Property Selection: Variable Wavespeed WC Values

Chapter 11: Capacity Determination 11.1 Capacity Evaluation Considerations For capacity evaluation by the 8G, CAPWAP ® analysis is ALWAYS recommended to check the 8G Case Method result. Hence, standard-of-practice is to use both Case Method and CAPWAP together which increases reliability compared to the Case Method alone. In order to make reasonably accurate capacity predictions, there are a few simple conditions/terms the user needs to get familiar with. These conditions/terms are explained in subsequent sections of this chapter.

11.1.1 Capacity Gain/Loss with Time During driving, the natural soil strength along the shaft is often reduced temporarily by the installation process and is regained with time after installation. Usually the capacity increases with wait time, and this is called “set-up”, and is associated with an increase in the shaft resistance. To take advantage of this capacity increase, testing the pile during a restrike will generally result in a higher capacity evaluation and therefore a more economic foundation.

Capacity Determination: Capacity Evaluation Considerations

132

Figure 11.1: measurements indicate a capacity increase over a 35 min waiting period due to soil set-up (Example EX-1) For cohesive soils, set-up is usually the result of pore pressure changes and thus is linear with log-time, and may continue for many log time cycles (although it is usually not practical to wait more than a week or at most a month to evaluate the long-term capacity). For cohesive soils along the shaft, short term restrikes (15 min to 1 hr) with additional restrikes at one day may allow projection of the shaft increase to later times using this principle of linear increase with log time; of course a later restrike should be also performed to confirm this projection. Selecting an early high energy blow (before the capacity begins to degrade in the more sensitive soils) is recommended for analysis, and it is therefore also important that the hammer be increased rather quickly to optimum performance (rather than slowly being started over many blows). Ideally, the hammer will be at optimum performance by blow two or three of the restrike For coarse grained soils, set-up is generally the result of lateral pile whipping during installation which creates an arching effect around the pile shaft; restoration of the normal earth pressures and hence the restoration of long-term shaft resistance is generally a linear process with time, with a limiting time duration (perhaps of a week). “Aging” or restoration of chemical cementing is also more likely to increase linearly with time. Capacity decrease with time, commonly called “relaxation”, has been observed, although fortunately less frequently. In dense saturated silts (or soils with similar moderate drainage), it occurs on the end bearing alone due to negative pore pressure effects, which increase the effective stresses during driving and hence capacity at the toe. With time the normal pore pressures are reestablished and the effective stresses and hence end bearing are reduced. Typically this may occur in a relatively short time period (perhaps a day or less). For piles driven into a weathered shale formation, substantial relaxation has also been observed both in end bearing and in shaft resistance in the

Capacity Determination: Capacity Evaluation Considerations

133

shale formation. Testing after at most 7 days for relaxation in shale should be sufficient. In any case, for relaxation cases, select an early high energy blow for analysis.

11.1.2 Capacity Mobilization The set per blow must be at least 3 mm (0.1 in) per blow or blow counts in excess of 340 blows per meter (100 blows per foot) to assure that the full soil resistance is mobilized. If the set per blow is less or blow count higher, the test has potentially only mobilized part of the total soil resistance, and the capacity result will be only a lower bound estimate as it indicates only the resistance activated. This may often occur when the pile is driven to a low set (high blow count) at end of driving and then due to capacity increase with time (set-up), the set per blow will be even smaller (blow count higher) during restrike. If this situation arises, possible suggestions include: •

This may require in some cases a bigger hammer or a larger drop weight (larger ram weight), or a higher drop height, than used during installation. Usually a weight of 2% of the desired ultimate test load is sufficient. It should be mentioned that using higher weights (like 5% of the ultimate test load) allows the user to satisfy the requirements for Rapid Load Testing (ASTM D7383). Using a higher drop height (stroke) should be used only if the stresses are still in the acceptable range relative to the pile material strength.

•

If and only if there is very low set per blow or high blow count during restrike, the end of drive end bearing can be added to the restrike shaft resistance to compensate for perhaps not activating the full end bearing capacity of the pile during restrike and to project a higher total. This can be done when there is good knowledge of the soils, particularly at the toe, and preferably where there is local experience, perhaps including a static load test, and when it is reasonably certain that toe relaxation will not occur.

•

For closed end pipe piles, it is possible to increase the pile impedance by completely filling the steel shell with concrete, and letting it cure, before the restrike. The increased impedance of pile then causes a higher force input which in turn can overcome higher soil resistances.

•

In some cases, such as small projects with relatively few piles, the conservative lower bound solution may be sufficient. For large projects, mobilizing the full capacity is desirable as cost savings from the full capacity used in the design make the extra effort economically justified.

11.1.3 Correlation with Static Tests For proper correlation of static and dynamic tests, the static load test must be run to failure and the dynamic test should usually be a restrike as described in Section 11.1.1. Additionally, dynamic tests must sufficiently displace the pile as described in Section 11.1.2. The capacity estimated by the dynamic field test in conjunction with CAPWAP usually correlates best with the Davisson limit load method (often regarded as one of the more conservative evaluation methods). If the static load test is a rapid plunging failure, then all failure load interpretations will be similar. If Davisson is not the method used in evaluation, then a correlation between Davisson and the other method can be established, but the correlation must account for end bearing differences (pile type and soil type at pile bottom) to estimate the other load method result from either the CAPWAP ® or Davisson result.

Capacity Determination: Capacity Evaluation Considerations

134

The safety factor should relate to the number of tests. For a given ultimate capacity, a lower safety factor can be assigned if a larger percentage of piles are tested (or alternatively stated, a higher allowable load can be used) since some of the uncertainty is removed by this more extensive testing. Many codes recognize this truth (e.g. Eurocode, AASHTO 2009, Australian AS2159, et al). In summary, the dynamic test should be a restrike with a similar wait time after pile installation. Both static test and dynamic tests must cause soil failure (the dynamic test must achieve a sufficient set per blow), and static test should use Davisson interpretation method. More testing should result in a more efficient and thus less costly design.

11.2 Capacity Methods The biggest challenge for a 8G user is to be able to accurately predict pile capacity. If the user makes a mistake, it could potentially turn into a very costly one. However it is also the most rewarding when the 8G can reduce expensive static testing or determine that length and cost of a pile foundation can be reduced. Unfortunately, it is impossible to give guidelines that apply to all situations. In general, the following capacity methods are available to the user performing dynamic testing: •

Case Method

•

CAPWAP

•

iCAP

•

Energy Method

®

®

11.2.1 Case Method Capacities All “Case Method” capacities are closed-form solutions that can be computed immediately for every blow in real time. These solutions require that the pile be linear elastic and that the cross section be uniform along the pile length. For non-uniform piles, the CAPWAP program can accurately model non-uniform piles, and should be used for capacity determination (Section 11.2.3 on page 139). Even for uniform piles, stateof-practice would require confirming any Case Method result with CAPWAP.

Capacity Determination: Capacity Methods

135

11.2.1.1 RSP Method

Figure 11.2: RSP calculation is made from the initial time markers noted on the graph The RSP method uses empirical damping factors JC determined from soil type (implies the soil is properly identified by grain size, and that the soil at the boring is similar across the site). The empirical study included data primarily from restrike (or end of driving in sands) with moderate blow counts. Unfortunately, the RSP method is sensitive at low blow counts; small JC changes can make large capacity changes. For large soil quakes, the full toe resistance may not be fully active at 2L/c unless a time delay is used. For concrete piles with 2 peaks (from non-uniform pile cushion compression), selecting the second peak (use a delay DL) usually gives a better solution. View RT-RS curves and adjust JC until a “flat” curve is obtained; however as shaft friction increases, this technique becomes less reliable. Details on how the PDA-S program calculates the RSP method are detailed in Appendix A Section A.4.5. The RSP method is generally historical and now rarely used directly.

11.2.1.2 Shaft Resistance Estimation The PDA-S program is able to calculate a very rough estimate of the shaft resistance in a pile using the Case method. For shaft friction, the SFT computation makes no allowance for damping. The SFR quantity has a crude correction based on the current JC selection. This method may also be used with quantities SF0 through SF9 where the last number reflects the Case damping selection (note that SF0 and SFT are essentially the same quantity). Additionally the PDA-S can calculate where the shaft resistance is being developed along the length of the pile. This may be presented numerically with the SFL1 through SFL9 quantities where the last number indicates the shaft resistance developed over a percentage of the length of the pile in ten percent increments (i.e.SFL5 will calculate the

Capacity Determination: Capacity Methods

136

shaft resistance in the upper 15m of a 30m pile). This computation uses the damping constant JC

Figure 11.3: Shaft Resistance distribution versus depth These calculations are perhaps better suited for graphical presentation and can be done so using the ‘Rs Distribution’ window. This may be accessed by clicking the vertical graph button and selecting the ‘Rs’ tab. This graph, Figure 11.3, will plot shaft resistance versus depth with a calculation of total resistance, shaft resistance (and percentage of total) and end bearing (and percentage of total). Please keep in mind that as with all Case Method Capacity Estimations, they are only intended for uniform driven piles. CAPWAP analysis should always be performed to confirm estimations and ultimately will yield much more reliable results when properly performed. For details on how the PDA-S program calculates Static shaft resistance please see Appendix A Section A.4.9.

11.2.1.3 End bearing Capacity Estimation Similar to the SFR quantity the PDA-S program is able to calculate a rough estimation of the end bearing with the EBC quantity. The EBC quantity has a crude correction based on the current JC selection. This method may also be used with quantities EB0 through EB9 where the last number dictates the Case damping selection. Details on how the PDA-S program calculates static end bearing are noted in Appendix A Section A.4.9.

Capacity Determination: Capacity Methods

137

11.2.1.4 RMX Method

Figure 11.4: The RMX method accounts for soil elasticity and pile toe displacement The RMX method searches for the maximum resistance during the entire blow and thus overcomes some of the limitations of the RSP methods for small or large blow count, or high quake situations. Many find a JC of 0.7 for RMX (or RX7) gives a good first estimate. Although temptation exists, do not use damping factors less than 0.4 with this RMX method without substantial proof from CAPWAP or a static test that a lower damping factor correlates well. For friction piles in clay (where high damping factors are normally appropriate), the full resistance should be active during the first 2L/c cycle anyway (RSP = RMX). Sensitivity to the damping factor can be studied by viewing multiple results (e.g. RX5 for JC of 0.5 and RX8 for JC of 0.8 etc). Details on how the PDA-S program calculates the RMX method are noted in Appendix A Section A.4.6.

11.2.1.5 RAU/RA2 Method For uniform piles with zero shaft resistance, the RAU method is theoretically the perfect method as all theories are correct and the method is independent of a damping constant. It makes no difference if it is easy or refusal driving; the key is that the force and velocity must be proportional for the entire first 2L/c (implies good data) and the 2L/c must be correctly chosen. The method RA2 has shown considerable promise in determining the ultimate load even for piles with little to moderate shaft resistance and this method also does not require the selection of a damping factor. Results are generally in good (not necessarily great) agreement with results from CAPWAP and therefore the method deserves at least a casual consideration on every project. If RA2 differs from the damping factor methods (e.g. RX7), then investigate further. If the pile is driving through a layered soil, the RA2 method has the additional advantage that the damping factor does not need

Capacity Determination: Capacity Methods

138

adjustment. Again, 2L/c must be chosen correctly. Details on how the PDA-S program calculates RAU are noted in Appendix A Section A.4.7.

11.2.1.6 RSU Method

Figure 11.5: The RSU method accounts for early unloading For longer piles with high friction distributed along the shaft, the velocity may become negative prior to 2L/c and the upper soil layers begin unloading even prior to the loading of the lower soil layers. Because the total soil resistance is then not activated simultaneously, most all methods then underestimate capacity and the unloading method RSU may be beneficial (RSU attempts to determine how much friction has unloaded and adds it back into the equations as a correction factor). RSU uses the JC damping factor (RU7 is RSU with JC = 0.7). However, CAPWAP (or static test) should be performed as soon as possible to verify the correct procedures. Details on how the PDAS program calculates the RSU method are noted in Appendix A Section A.4.8.

11.2.2 Damping Constant JC The damping constant JC applies only to the basic Case capacity computations RMX, RSP, and RSU. To change the damping factor type JC value (e.g. JC0.45 will make JC equal to 0.45 after approval on the ‘Pile Properties’ dialog box). This may be helpful when viewing resistance on the graph. The capacity methods can be selected for certain damping factors by the quantity selection. For example RX5 is RMX with JC of 0.5. Using these specific quantities (e.g. RX4, RX6, Rx8...) rather than the general RMX gives perhaps a more clear indication of the method and further allows the user to select more than one damping factor to view

Capacity Determination: Capacity Methods

139

the sensitivity (e.g. select both RX4 and RX7). Similarly, RP5 and RU5 are RSP and RSU respectively with a damping factor of 0.5. Shaft Friction resistance (SFR) and End Bearing (EBR) reflect the damping constant JC, while SF5 and EB5, for example, reflect the damping factor 0.5. Based usually on the soil at the pile toe, the following are given as general guidance. Recommended Case damping constant JC values for the RMX methods are: •

0.40 to 0.50 for clean sands

•

0.50 to 0.70 for silty sands

•

0.60 to 0.80 for silts

•

0.70 to 0.90 for silty clays

•

0.90 or higher for clays

The RMX method is preferred. RMX is particularly useful when moderate to high soil quakes are expected or observed. The RX7 method is equivalent to RMX with a damping factor of 0.7. Caution is given for low blow counts (high set per blow) to be conservative as low blow counts are indicative of low capacity. It would be helpful to reduce the hammer energy to obtain a higher blow count (smaller set per blow). Many also compare results with the RA2 method (which is independent of JC). Recommended Case damping constant JC values for the RSP methods are: •

0.10 to 0.15 for clean sands

•

0.15 to 0.25 for silty sands

•

0.25 to 0.40 for silts

•

0.40 to 0.70 for silty clays

•

0.70 or higher for clays

Generally, the RSP methods are rarely used because there are better methods available. RSP sensitivity to JC increases for finer soils or at low blow counts. For long piles where the velocity goes negative before 2L/c, the unloading methods (RSU) may be appropriate and these RSP damping factors are then appropriate for the RSU methods also. Unless grain size analysis is available, visual inspection of the soil may be misleading. A lower prediction results by selecting a higher JC. A soil plasticity index(P.I.) above 5 may imply larger JC values.

11.2.3 CAPWAP Capacity The Case Method in the field using a damping factor JC allows a capacity estimate. In all cases, we highly recommend CAPWAP signal matching analysis of the data as a better way to estimate pile capacity. CAPWAP is a rigorous numerical analysis which models the pile and soil behavior. CAPWAP also produces a simulated static load test curve. After the CAPWAP analysis, a JC value can be chosen to estimate the CAPWAP result (or a static load test failure load if the pile has been tested statically). It is important to realize that

Capacity Determination: Capacity Methods

140

careful CAPWAP analysis is standard practice for the high strain dynamic pile testing method when assessing pile capacity. The CAPWAP program can accurately model non-uniform piles, and should be used for capacity determination for all non-uniform pile cases. For all practical purposes, it is recommended that at least one CAPWAP be performed in order to confirm field methods. For larger projects, it is recommended to perform CAPWAP for at least 30 to 50 percent of tested piles, although usually only for the data at the end of drive and/or begin of restrike. Inspecting resistance distribution, unit friction values, and end bearing determined by CAPWAP (for restrikes and end of drive) and comparing with soil boring and static analysis calculations often results in better recommendations of total capacity, optimum driving criteria or pile length. Further discussion of CAPWAP is beyond the scope of this manual and the user is directed to refer to a separate CAPWAP Manual, also published by PDI.

11.2.4 iCAP Capacity

Figure 11.6: iCAP results shown in the vertical graph as well as output quantities The iCAP program, if installed on the 8G, generates blow by blow capacity solutions in real time and offers the user a higher level of confidence in determining pile capacity during testing. These iCAP capacities are generated by algorithms similar to the autoCAPWAP feature available in the CAPWAP program. The iCAP capacity results assume that the pile is uniform (cross section and modulus versus length). If the pile is not uniform, these results may not be reliable. The iCAP program may also be installed on a PC and operated from PDA-S program during remote data collection or post processing. For more information on ICAP and its operation, please refer to “iCAP® Operation” on page 159.

Capacity Determination: Capacity Methods

141

11.2.5 Energy Method Capacity calculations for the measured Hiley formula (also known as Energy Approach) showing capacity as a function of the maximum energy (EMX) and set per blow is accessed by the QUS, QUT and QBC quantities. This formula has been researched by Paikowsky and recommendations are to use it only with end of drive data. Further the factor ‘k’ must be set to values less than 1.0 (values between 0.75 and 0.5 are common; logic would suggest lower values for cohesive soils and/or for lower blow counts) Each of the capacity calculations will use either the user defined set (through the CAPWAP adjustment window), measured DFN, or the blow count from the entered LP values. In use, the ‘k’ factor reduction must be applied to all three energy capacity calculations. Additionally the PDA-S program includes the RQX capacity estimates where the programs reports the greater value of the Case Method RMX formula or the QUT value (assuming a k value of 0.5). This method may be of some value when testing larger diameter shafts, though CAPWAP confirmation is required. This method is provided for convenience only; PDI does not endorse the use of this method. For further information regarding the Energy formula please see Appendix A Section A.4.10.

11.3 Additional Considerations/Suggestions The 8G is obviously a very powerful analysis tool when properly applied. From the preceding it is shown that capacity determination is a complex problem with many features contributing to the testing success (or failure). Obviously good quality measurements are required; if the data quality is poor then any analysis is suspect. Organizations with 8G units should make every effort to make measurements on all of their in-house pile projects as it will detect most common problems, and reduce liability. Some suspect cases are in reality due to poor hammer performance at the end of driving causing relatively high blow counts, and the hammer performing much better during restrike or redrive, resulting in relatively lower blow counts; the 8G can easily identify these cases by looking at the hammer performance indicator EMX. Soils are difficult. Some of those difficulties encountered are (but not limited to): •

Site soil variability may cause complications.

•

Clean coarse grained sands are generally well suited to dynamic capacity analysis, even at the end of driving, since capacity changes with time are usually minimal. However, end bearing in larger diameter displacement piles, may be under-predicted at higher blow counts.

•

Changes in water table and effective stresses between time of testing and the service condition will have an affect on the long term pile capacity. Particularly seasonal variations or if the site has been temporarily de-watered for construction. The geotechnical engineer should review these changes, as well as settlement concerns for the piles, and pile groups, as well as scour and other concerns when adapting the dynamic testing results into his design and installation criteria.

Capacity Determination: Additional Considerations/Suggestions

142

•

Larger diameter open ended pipe piles (or H-piles which do not bear on rock) may behave differently under dynamic (no plug effect) and static loading conditions (plug develops), and caution when testing these piles is suggested.

•

For piles driven to a fat clay layer at the pile toe, the toe resistance may be overpredicted and great caution is given to discounting any high apparent end bearing.

•

In cases where the pile is driven to high blow count with significant end bearing and then large additional shaft resistance from setup occurs (so that the blow count on restrike is very high), it may be beneficial to stop one pile just above the bearing layer (low tip resistance) such that on restrike the full shaft resistance may still be mobilized. The user may consider combining that shaft resistance from restrike with the end bearing at end of drive for the pile driven into the bearing layer if the restrike blow count is very high.

Numerous other factors are usually considered in pile foundation design. Some of these considerations include additional pile loading from downdrag or negative shaft resistance, potential liquefaction layers, soil setup and relaxation effects, cyclic loading performance, minimum embedment requirements due to lateral and uplift loading, effective stress changes (due to changes in water table, excavations, fills or other changes in overburden), scour requirements, settlement from underlying weaker layers and pile group effects. These factors are not evaluated by the 8G and need to be considered in the interpretation of the dynamic testing results. The foundation designer should determine if any of these considerations are applicable to his project and the foundation design. CAPWAP confirmation is always recommended as it better determines soil behavior and identifies unusual soil conditions; when conditions are unusual, static tests should be recommended.

Capacity Determination: Additional Considerations/Suggestions

Chapter 12: Pile Stresses 12.1 Stresses - Significance and Types The 8G user should always know the maximum stresses (or forces) so that the driving stresses can be determined and kept between recommended limiting values (Section 12.4).

12.1.1 Compression Stresses

Figure 12.1: Collapsed pile top illustrates the importance of monitoring pile stresses Measurement of average maximum compression force (FMX) and stress (CSX) equip the user to detect the likelihood of damage to the pile top. The maximum force FMX is the compression force at the transducers (computed from the average measured strain multiplied by the modulus multiplied by the cross section area) and needs little explanation; the force could be slightly higher just above a point of high shaft resistance

Pile Stresses: Stresses - Significance and Types

144

along the shaft, but this increase would be modest and not likely to cause pile damage compared with pile top damage from local contact stresses or bending stresses due to non-perfect alignment. For piles with cross sectional area changes along the length, wave equation studies should be made to find a stress amplification factor. The 8G unit can quantify the effect of reduced throttle settings or air pressures, stroke or drop heights, changes of the helmet or cushions on the stresses induced at the pile top. The 8G can determine maximum bending stress (in the plane of transducer attachment) in either individual strain transducer (CSI) to aid in hammer pile alignment. Further information regarding how the PDA-S program calculates stress values at the pile top is described in Appendix A Section A.5.1.

12.1.2 Static Bending Stresses on Piles Driven on an Incline When an unsupported length of pile is driven on an incline, it results in static bending stresses from the weight of the pile and or the weight on the pile driving hammer. In such cases the user should be aware that static bending stresses combined with dynamic stresses from impact may exceed the minimum yield strength of the pile even though dynamic stresses may be within recommended limits. Please note that static bending stresses cannot be assessed by the Pile Driving Analyzer and such considerations should be performed prior to driving. The Offshore version of GRLWEAP can perform this analysis during hammer approval or prior to testing.

12.1.3 Stresses at the Pile Toe

Figure 12.2: When driving to hard end bearing layers; critical stresses may likely be at the pile toe The input wave is transmitted to the toe and, for piles with little friction, if a stiff end bearing is present, a compression wave will be reflected if this resistance is large relative to the input force. This can potentially result in a doubling of the stress at the pile toe in this “fixed end condition case”. The compression force (CFB) or stress (CSB) can be

Pile Stresses: Stresses - Significance and Types

145

computed for the pile bottom; this can help determine if toe damage is a possibility. It should be noted that this is a computation (computed toe force is equal to the total resistance, RTL, minus half the total shaft resistance, SFT) and is not a measurement. Further, this computation is a one dimensional assessment that requires a uniform pile cross section with length. The one dimensional analysis also ignores potential local stress concentrations. For instance when an H pile encounters a sloping bedrock or if the pile encounters a massive obstruction at an oblique angle. Local stresses at the toe can therefore exceed this computed toe stress, so the nature of the soil profile should be considered. Therefore, a conservative approach is warranted evaluating stresses at the pile toe such that the limiting force (stress) at the bottom should be lower than the limit for the pile top. Toe reinforcement often helps prevent toe damage. Further information regarding how the PDA-S program calculates stress values at the pile toe is described in Appendix A Section A.5.2.

12.1.4 Tensile Stresses

Figure 12.3: Tension cracking in a concrete pile The maximum tension force is generally of interest for concrete piles since concrete performs poorly in tension. Generally, tension is higher for longer piles and during easy driving, although for large quake soils, high tension stresses can still be a problem even for refusal driving. The computed tension force (CTN) only considers the maximum net tension from the first returning wave from the toe (maximum upward tension at 2L/c plus the minimum downward compression at any time during the first 2L/c); the maximum force (CTX) also considers the maximum downward tension wave late in the blow (and subsequent upward compression in the following 2L/c). These forces (CTN and CTX) can be translated into stresses TSN and TSX respectively. Further information regarding how the PDA-S program calculates tensile stress values in the pile is described in Appendix A Section A.5.3 and Section A.5.4.

Pile Stresses: Stresses - Significance and Types

146

12.2 Tension Envelope

Figure 12.4: Fig 12.1: Tension Envelope A visual depiction of the tension as a function of pile length can be viewed by clicking on the vertical graph button and selecting the TE tab. The scale is relative and automatically selected to the maximum result for each data set. The maximum tension (TSX) and the tension (TLS) at the LS location are displayed. TLS at location LS is useful in assessing the tension at a specific splice location. The TLS parameter can also be selected as an Output Quantity. A screen shot of a Tension Envelope apparent on an 8G unit is shown in Figure 12.4.

12.3 Recommended Stress Quantities Using the input pile area (AR), 8G calculates the maximum compressive stress (average FMX/AR = CSX; or max of any individual strain CSI) and, for concrete piles the tension stress (CTX/AR = TSX, or CTN/AR = TSN). The compression stress at the pile bottom (CSB) can be estimated from (CFB/AR). These quantities (CSX, CSI, TSN, TSX, CSB) can be computed and eventually summarized numerically and for later plotting by PDIPLOT. It is recommended that driving stresses be included in the results requested for computation and display.

Pile Stresses: Tension Envelope

147

12.4 Stress Limits High driving stresses are a leading cause of pile damage. If either compression (top or bottom) or tension driving stresses are too high, the cushion could be increased or the hammer energy reduced (lower stroke). It is recommended to limit compression driving stresses (CSX) to values indicated in Table 12.1 for different pile types.

Table 12.1: CSX Limits for Various Pile Types Pile Type

CSX Limit

Steel

0.9Fy

Concrete

0.85f’c - prestress

Timber

3 x (allowable design stress)

Tension stresses for prestressed concrete piles are often limited to:

3 f c + f pe

(English units in psi)

0.25 f c + f pe

(SI units in MPa)

where f c is the compressive strength of the concrete and f pe is the effective prestress from reinforcing steel. Tension stresses for regularly reinforced concrete piles are ofter limited to:

AS 0.7f y  -----Ac

(where A S is the area of the steel and A c is the area of the concrete)

Bending stresses can superimpose on the axial stresses and create critical situations. The leading causes for bending are poor hammer pile alignment and pile tops which are not perpendicular to the pile axis. Every effort should be made to keep the bending as measured in the difference between diametrically opposite pairs of measured strains at a minimum. Another cause of local top damage is poorly fitting helmets (too small, too big, or non-flat impact surfaces).

Pile Stresses: Stress Limits

148

Pile Stresses: Stress Limits

Chapter 13: Hammer Performance 13.1 Overview Pile driving blow count (or set/blow) depends on soil resistance, impact stresses and energy transferred to the pile. Refusal blow counts (very small set per blow) can be caused by either high soil resistances or poor hammer performance. Hence, hammer performance should always be evaluated. If a hammer is not working well, the energy transferred to the pile ‘EMX’ will be relatively low and it will take longer to drive the pile, so productivity suffers. Also, if the hammer is not performing well and a blow count or set per blow is used as the pile acceptance criteria, then the pile could be accepted prematurely at an actual pile capacity which is dangerously low, and foundation failures could result. It is generally to everyone's advantage to have a well performing hammer so the contractor gets completed as efficiently and quickly as possible, and just as importantly the engineer is assured that the pile embedment is sufficient and the capacity is adequate.When a blow count (or set/blow) is part of the driving criteria, as is almost always the case, it is also important that the hammer perform consistently during the course of any project, so periodic testing for hammer performance is recommended.

13.2 Energy Measurements The 8G computes energy transferred from the integral over time of the product of force times velocity (equivalent to the work done on the pile). The maximum energy ‘EMX’ can be compared with the hammer's rated or potential energy ( E p = W r h ) to determine an energy transfer ratio ‘ETR’, which is an indication of the overall efficiency of hammer driving system. ETR compares EMX with the manufacturer’s rating, while ‘ETH’ compares with the potential energy from the computed hammer stroke for open end diesels. The maximum transferred energy EMX) is typically 20 to 60 percent of the manufacturer's rated energy, ER, depending on pile and hammer type. Lower energy transfer ratios usually indicate a hammer in need of repair or a driving system in need of modification. Typical hammer performance can be assessed in Appendix D, showing statistical histograms of transfer ratios for different pile type/hammer combinations. These figures

Hammer Performance: Overview

150

relate energy transfer ratios at the end of driving. Compare measured energy EMX with predicted performance from a wave equation analysis (i.e. GRLWEAP). Effects of changes in hammer cushion, helmet or pile cushions and throttle settings are easily observed. Pre-ignition of diesel hammers, or pre-admission of air hammers, can be detected. The hammer operating rate in blows per minute ‘BPM’ can be determined by the PDA, up to the speed limit of the PDA. If the 8G misses a blow during acquisition, the BPM value of the PDA will be half the actual BPM; this can be corrected by the ‘Blow Number Filter’ function (Section 8.5.2.1 on page 107). A new output quantity is the time from rise to peak ‘TRP’ which is a measure of rise time (in milliseconds) which in turn depends on hammer cushion, helmet weight and pile cushion when applicable. The effectiveness of different hammers can be compared. Hammers with similar rated energies but of different types, or hammers of the same model, can be compared for their performance by the energy transfer, input forces, and overall effect on the blow count. In general hammers with higher stroke (e.g. diesels) work best when high capacity or deeper embedments are required and hard driving is anticipated. Heavier rams with shorter strokes (typical of air or hydraulic hammers) are very effective in softer soils or in cases where much of the capacity comes from set-up.

13.3 Hammer Stroke (Open-Ended Diesel Hammers) For Open End Diesel Hammers only, the ram stroke (STK) may be computed from blows per minute (BPM) from the equation s 60 2 h  ft  =  4.01  ------------- – 0.3 (English Units) BPM 60 2 h  m  =  1.22  ------------- – 0.1 (Metric or SI)   BPM  The potential energy for open end diesel hammers can be computed from this stroke (STK or h) times the hammer’s ram weight, W. This calculated potential energy can then be compared to the maximum energy transferred to the pile, EMX, and reported as ETH, the hammer transfer efficiency ration, normalized for the computed hammer stroke.

13.4 Calculations for External Combustion Hammers Further analysis of dynamic test data is possible by looking at the momentum calculations (MF0 from force, or MW0 from wave-down). If the ram weight ‘WR’ is input, the maximum ram velocity at impact ‘VRI’, (for ECH hammers only) can be calculated from MF0. (VRI = MF0/WR) and used to compute the ram’s kinetic energy . 1 2 E k = --- m ram v 2 Comparison of the kinetic energy with the rated energy, to give actual hammer efficiency, or with the transferred energy EMX may help determine where the energy

Hammer Performance: Hammer Stroke (Open-Ended Diesel Hammers)

151

losses are occurring (e.g. primarily in the hammer or the lower driving assembly). These momentum equations can sometimes lead to unusual answers and results should be viewed with judgment and accepted only if reasonable. For external combustion (air/steam/hydraulic or drop) hammers on steel piles, the force in the hammer cushion, ‘FCP’, and the hammer cushion stiffness, ‘KCP’, can be computed. These computations require input of the helmet weight ‘WH’, and weight of the ram ‘WR’.

13.5 SPT Energy Measurements The 8G energy measurements of EMX are also applicable to SPT soil samplers and dynamic penetrometers according to the ASTM D4633 Standard (and also as mentioned in ASTM D6066) where the term EFV is used (EMX and EFV give exactly the same result). Due to high accelerations, SPT subsections are instrumented with glued-on foil sensors rather than using bolt-on strain transducers (contact PDI for details). SPT energy measurement allows evaluation of a normalized N-value (called “N 60 “) to compensate for variations in SPT device efficiencies to improve upon soil strength estimates from SPT-N values. N 60 can be computed from the measured N, the measured energy transfer (EMX), and 60% of the theoretical potential energy Wh for the SPT ram (Wh) from the expression

 N  EMX  N 60 = ---------------------------- 0.6W  h  The 8G has an optional software add-on program (SPT ANALYZER) that specifically meets the sampling rate and filtering requirements of ASTM D4633 and the European norm. It provides for higher sampling rates and also has a higher analog filter cutoff (less analog filtering of the signals. Further details regarding the operation of the PDA-S software in SPT mode are covered in “SPT Data Collection” on page 175.

13.5.1 Historical note on SPT Energy Calculation It should be noted that a previous obsolete version of ASTM D4633 was a measurement standard that had been withdrawn. It considered the normal proportionality of uniform rods between force and velocity and therefore required only measurement of force and obtained energy from the integral of the force squared (divided by impedance). The result of this computation are given by the 8G in the quantity ‘EF2’. The method also required several “correction factors”, particularly for short rods. These correction factors are NOT contained in EF2 but must be applied separately. However, when rods are nonuniform, this proportionality assumption is in error and the results are also misleading. Errors were also potentially serious for the joint masses, and particularly if the joints were loose causing early tension reflections. The time ratio of first tension return compared with the theoretical 2L/c is shown by the quantity ‘RAT’, which was specified to be between 90 and 120% for a valid test. To avoid the complexity, and possible errors from this EF2 method, and considering that the correct method of energy evaluation integrating the product of force times velocity is contained in the EMX method, the EMX method is now the de facto standard in ASTM D4633 and in use by many test agencies today and is the PDI endorsed method of SPT evaluation.

Hammer Performance: SPT Energy Measurements

152

Hammer Performance: SPT Energy Measurements

Chapter 14: Pile Integrity 14.1 BETA (Integrity / Damage Evaluation) Normally, the wave up is a monotonically increasing function during the first 2L/c after impact due to the shaft resistance which causes upward traveling compression waves. Damage along the shaft of a pile returns an upward traveling tension wave. This tension (negative) from damage is superimposed on the compression (positive) due to soil resistance reflections causing a local relative decrease in the wave up function.

Figure 14.1: Minor damage propagating at splice location (example EX-24B; BN:688)

Pile Integrity: BETA (Integrity / Damage Evaluation)

154

The 8G inspects the wave up curve for local minimums and when present, signals that the pile is damaged. Figure 14.1 shows an example of wave up (red curve) for a pile with damage near it’s splice location. The warning is in the ‘warnings and limits’ area just under the Menu Bar and above the graphical data in the screen. It also appears as a vertical line on the graph which shows the Beta factor ‘BTA’ and damage location ‘LTD’. (The vertical line type and color can be user defined in Section 7.3.) The length to damage LTD evaluation can be enhanced using the ‘LS’ function (for example, if a pile is spliced at 35 meters below sensors, then enter the length to the splice as described in Section 4.3.3.4; the LS and LTD lines can then be compared visually to see if the damage is near the splice, as is often the case). LS - The Length to Splice can be entered and a vertical line will appear at this depth (below sensors) on the graph (at time 2*LS/WC after the initial rise marker).

Figure 14.2: Major damage at splice location (example EX-24B; BN:708) Nominally the BTA factor represents the percentage of pile cross section compared with the full cross section. However, short local defects may be under estimated by the method. The QBTA or ‘quick beta’ function always does a preliminary scan for damage even if BTA is not selected. The damage search was extensively improved in 1995. BTA can now find up to two damages (BTA and BT2 at LTD and LT2 respectively). It is suggested that the user consider and investigate the possibility of local bending as a possible alternative if damage is near the pile top. Soil resistances above the damage complicate the issue although a crude attempt is made to compensate for resistance. A subjective rating was developed to estimate the extent of damage based on the BTA value. However, piles which indicate possible damage should always be taken seriously and investigated. It may be possible that apparent damage is caused by bending stresses, or poor quality data (e.g. noise on the signals).

Pile Integrity: BETA (Integrity / Damage Evaluation)

155

The first question to ask is if the pile is non-uniform, or if a splice detail is causing a false indication. If stresses are high, try to change the driving system (more cushion or lower stroke) to reduce harmful stresses for further production piles. If the pile is a closed end pipe, drop a tape inside to measure the length or a light lowered (if sunshine, reflect from a mirror) will allow visual inspections. Replay the forces and check if bending is severe in the records which could cause a minor disturbance in the data and therefore a false indication. Is the ‘damage’ caused by a splice or other pile non-uniformity? Is the ‘damage’ caused by the data quality? Can it be ‘eliminated’ with FF adjustments? A false indication can also be caused by a phase shift between force and velocity. To investigate and correct for phase shifts you might try using the VT function (see Section 8.2.1) to eliminate the shift (e.g. VT0.03 to shift velocity to the right or VT -0.03 to shift to the left). Real damage should cause consistent readings from blow to blow. Defects near the bottom of the pile may be caused by the wrong wavespeed or the wrong pile length, so correct entry of these values is important. For concrete piles, inspect the earliest easy driving blows to determine the real WS. Using higher sampling frequencies may give earlier warning for toe damage to steel piles. Compare the later blows with earlier blows and look for sequentially earlier return of the tension wave to detect damage. Large shaft friction on long piles causes the velocity to become negative prior to 2L/c; if this condition exists, the BTA computation may incorrectly indicate damage. Look for a relatively sharp decrease in wave up to confirm damage. Gradual decreases in these early unloading cases may only result from the early unloading and not necessarily damage. If damage is detected, the engineer should always review the result to determine if the reading is true (or potentially false). This review is best done by inspecting the wave up curve in the first 2L/c for sharp local decreases (smooth gradual changes may be due to soil resistance, early unloading, or sweeping piles or simply data quality; sweeping piles may be acceptable or deficient depending on the degree of sweep).

Table 14.1: Beta Values and Corresponding Damage Categories Beta Value (BTA)

Description

100%

Uniform Pile

80 to 99%

Slight Damage

60 to 80%

Damage

< 60%

Pile Broken

It should be noted that in Table 14.1, categories are suggested. However the difference between a pile with BTA of 81 and another pile with BTA of 79 is only minor. The rating scale is really a continuous function with no definite boundaries. Pile with larger damages (BTA values certainly less than 80) should be assessed for their suitability. Defects far down the shaft may in some cases be not a problem if the pile is a friction pile and has sufficient resistance above the damage. End bearing at the damage is generally unreliable since the top and bottom sections may be poorly aligned, or the reinforcing steel may deteriorate with time. Capacity estimates for damaged piles should be avoided. Broken piles should be assigned zero capacity and should be replaced.

Pile Integrity: BETA (Integrity / Damage Evaluation)

156

Note that there is a second integrity evaluation method called BTB (also available as a quantity output). The BTB looks at integral of the valley compared to integral of the pulse input - rather than just peak magnitudes as in BTA. BTA computation looks purely at the magnitudes of the wave up, while BTB also considers the width of the “potential defect”. Generally the two results are somewhat similar.

14.2 Beta Window A graphical representation of the size and location can be displayed by clicking the vertical graph button,

, and selecting the  tab. The user may select the ‘BTA, 2, T’

botton and the graph will display the beta value for any detected damage. Selecting the ‘LTD, 2, T’ will display the location of the damage (referenced from the top sensor location).

Figure 14.3: The Beta Window helps the user visualize the location and extent of pile damage

14.3 Beta Limitations Sometimes damage detected by the PDA during pile driving cannot be seen during restrike because of: •

soft cushion on restrike

•

setup and a higher friction

•

because cracks in concrete ‘heel’ with time after driving.

The high friction essentially prevents motion at the damage location and therefore no reflection waves are generated which would be indicative of the damage. In order to

Pile Integrity: Beta Window

157

‘see’ the damage during restrike, a much sharper impact (less thickness or more stiff cushion; or higher drop if high friction) would be required, however, that may also damage the pile top so care and caution are advised. Sometimes the restrike tests are not sufficient to evaluate a pile for integrity, particularly if the soil set-up is strong. For that reason, in Sweden for example (where they drive reinforced, jointed concrete piles through clay) pile integrity tests by the high strain method are best conducted at the end of driving. Bearing capacity tests, of course, must be performed after a setup period.

Pile Integrity: Beta Limitations

158

Pile Integrity: Beta Limitations

Chapter 15: iCAP® Operation 15.1 Overview

Figure 15.1: PDA-S program with iCAP The iCAP ® Program comes pre-installed on the 8G and can be installed on a PC as well for use with the PDA-S program. The software tool equips the user in making quick and approximate pile capacity estimates, both during testing and subsequent data analyses. The iCAP capacity is generated by algorithms similar to the auto-CAPWAP feature available in the CAPWAP ® program. The iCAP capacity results assume that the pile is

iCAP® Operation: Overview

160

uniform (cross section and modulus versus length). It must be noted that the main goal of iCAP is to help the user in capacity predictions during testing. Hence, iCAP results are considered approximate or preliminary in comparison with the more rigorous CAPWAP signal matching analysis, which is the recommended method to estimate pile capacity. A brief methodology on how the iCAP functions along with its operation on both, 8G and PDA-S are discussed in Section 15.12.

15.2 iCAP Operation

Figure 15.2: The iCAP program is accessed from the iMenu sub-menu After entering the data collection screen the user can navigate to the iCAP window from the iMENU sub-menu (Section 6.2) and clicking the button. The user activates the iCAP program by selecting the “Use iCAP” checkbox shown in Figure 15.2. By checking this box the iCAP analysis options will be activated and the user will be able to select and define different iCAP analysis options.

iCAP® Operation: iCAP Operation

161

15.2.1 iCAP Analysis Options 15.2.1.1 iCAP Qualifiers

Figure 15.3: iCAP Qualifiers highlighted in yellow The check boxes on the Left Hand side of the screen (shaded area of Figure 15.3) are a set of qualifiers that the user can activate and define to determine if and when the iCAP program should begin analyzing data for any particular blow. These qualifiers monitor each blow and if the defined qualifiers are satisfied, the automated iCAP analysis will begin.

Figure 15.4: Qualifiers assessing bending and proportionality The first three qualifiers (Figure 15.4) will also assess data quality but based on proportionality and bending at the first data peak (T1). THe user may modify these parameters. •

The F/V qualifier will evaluate the proportionality of the force and the velocity records. Under normal driving conditions, and with a uniform pile section, this value should be close to 1.0, however, several driving conditions may legitimately cause nonproportionality and/or long impact durations. Very short piles or very thick pile cushions for concrete piles may cause F/V proportionality out of range.

•

The V/V qualifier looks at the ratio of the two velocity measurements. Generally, this value should be very close to 1.0.

iCAP® Operation: iCAP Operation

162

•

F/F is a ratio of the two measured force curves and is indicative of eccentric bending forces in the pile.

All three ratios will be evaluated symmetrically (e.g. ¾ or 4/3).

Figure 15.5: Qualifiers assessing the data measurements Immediately to the right of the first three qualifiers, are data quality parameters (Figure 15.5), that assess if there are any problems with the data measurements. •

V Clip, and F Clip will monitor if there is any clipping in the Acceleration or Force Records during data acquisition.

•

V[END] will verify that the velocity measurements are properly returning to near-zero at the end of each record (prior to the automatic final adjustment).

Note that Pile Dynamics, Inc. recommends that these three parameters be checked (activated) as data that fails to satisfy these parameters should never be evaluated for capacity estimation.

Figure 15.6: The user may define the last four Qualifiers The last four qualifiers (Figure 15.6) are limits that the user is able to define. •

iCAP® Operation: iCAP Operation

Activating the BETA qualifier the user is able to define a minimum limit to the reported Beta values from the PDA before an analysis will begin (e.g. there is no reason to analyze

163

a severely broken pile). Users testing non-uniform piles or piles with significant impedance changes at the splice (splice plates or mechanical splices) should choose to reduce the limit or deactivate this qualifier. •

The EMX qualifier will allow the user to define a minimum energy value required for analysis.

•

The LP qualifier will allow the user to define a minimum penetration before the iCAP will begin analyzing.

•

Lastly the Resistance qualifier will allow the user to select a particular Case Method and set a minimum Case Method Capacity requirement.

Figure 15.7: Analysis options are located in the upper right of the iCAP window

15.2.1.2 ‘iCAP [#] Blows’ Criteria Typically used in post data collection analysis (data review mode), this menu allows the user to change the number of blows, starting from the current record, that will be analyzed when the “iCAP [#] Blows” button is pressed in the iCAP window (where [#] refers to the number of blows to be analyzed) and will also affect the ‘Do # iCAP’ button on the Operations Toolbar on the main screen in data review mode (Section 6.1).

15.2.1.3 Start iCAP Fresh for Each Record When the ‘Start iCAP fresh for each record’ is checked, iCAP will reset the initial soil parameters before each analysis. If this is left unchecked, iCAP will use the soil model parameters from the previous analysis as the starting point for the current analysis. Since the soil reaction generally changes slowly from blow to blow, the latter option should run faster, unless soil conditions change abruptly.

15.2.1.4 Save iCAP Result When the ‘Save iCAP result’ is checked, it causes the iCAP results and soil model for all analyzed blows to be saved in the PDA file, allowing the results to be later replayed and printed (e.g. in PDIPLOT). Using this option will result in slightly bigger PDA files but is generally recommended to make active (checked).

iCAP® Operation: iCAP Operation

164

15.2.1.5 Quick iCAP Sets the type of iCAP analysis that will be performed.Quick iCAP shortens the automatic search process by reducing the number of signal matching procedures performed before a result is returned (see Section 15.12). Quick iCAP will analyze more blows during data acquisition, since it is several times faster than full iCAP.

15.2.1.6 iCAP Timeout (min) Specifies the maximum amount of time that PDA-S will wait for an analysis to finish. If it does not finish by that time PDA-S will cancel the analysis and show the partial results. It is recommended to set this limit relatively low (e.g. one or two minutes should be sufficient).

15.2.2 Additional Analysis Options In addition to the analysis options described in Section 15.2.1, a few additional analysis options available ideally suited for desktop analysis.

Figure 15.8: Additional analysis options

15.2.2.1 iCAP New Doc The iCAP program will use the same soil model from the previous analysis to start subsequent analyses. If you click ‘iCAP New Doc’ before that, a new iCAP document will be created and all soil parameters will be reset. If ‘iCAP New Doc’ is not clicked and ‘Start Fresh For Each Record’ is not checked, then the soil parameters of the previous analysis will be used as the starting point for the new one.

15.2.2.2 iCAP Send FV At any time after data acquisition has stopped, or when replaying data, clicking ‘iCAP Send FV’ will start an analysis of the current blow.

iCAP® Operation: iCAP Operation

165

15.2.2.3 iCAP Send FV Output Creates an output file of the iCAP analysis for the current blow, which may be printed for reporting purposes. This file may also be saved and reopened in CAPWAP for further analysis as described in Section 15.9.1.

15.2.2.4 iCAP Cancel After an analysis is initiated, clicking “iCAP Cancel” will cancel the iCAP execution without updating the results.

15.2.2.5 iCAP Stop or clicking “iCAP Stop” will stop the iCAP execution and will update to the partial results.

15.2.2.6 iCAP Setup Defines the location for the PDA-S program to call iCAP.

15.3 Running iCAP

Figure 15.9: iCAP results being viewed in data collection

15.3.1 iCAP Operation During Data Collection Once the user has gone through file set-up and entered the data acquisition window in the PDA-S software, the user needs to put the system into accept mode and perform a ‘Calibration Pulse’ (Section 5.2).

iCAP® Operation: Running iCAP

166

The user may begin analysis of data by clicking the button which will immediately activate the iCAP program causing the iCAP title screen to flash temporarily and begin analysis on available data. Note that activation of the iCAP program using the button will use all previously defined qualifiers and analysis options. These analysis options may be modified by accessing the iCAP window (Section 6.2).

Pressing the

at any time during data acquisition will stop the iCAP program.

15.3.2 iCAP Operation During Data Review iCAP may also be run during data review on the 8G Main Unit or on a PC. In this mode the or buttons will be replaced by the button (where [X] refers to the number of blows to be analyzed). Pressing this button will enable the iCAP program and begin analysis similar to the button. The number of blows to be analyzed may be modified as described in Section 15.2.1.2.

15.3.3 iCAP Analysis Procedures Once iCAP has started inside the PDA-S program it will look at each blow and determine if that particular blow meets all the qualifiers defined in the iCAP window. Once the iCAP qualifiers are satisfied the iCAP program will begin analyzing that blows’ data (when in use during data collection the process will operate in the background while the PDA-S program continues to collect new data). The user is able to view the iCAP process from the Status Bar (Section 5.1.9). The Status Bar will indicate if the blow satisfied the iCAP qualifiers, and if so, which phase of the analysis process it is in. iCAP will not analyze calibration signals.

15.3.4 Viewing iCAP Results When an iCAP analysis is complete the results will be shown numerically and, if selected, also graphically.

iCAP® Operation: Running iCAP

167

Figure 15.10: iCAP results are shown both numerically in the FV graph and also graphically in the vertical graph By either selecting the iCAP Graph option in either the upper or lower graph or opening the vertical graph and selecting iCAP the graphic results and the numeric results are presented. The graphic result options include: •

the Wave UP ( WU) Match

•

Force versus Depth (e.g. force in pile at ultimate load), and

•

a simulated static load test curve.

iCAP® Operation: Running iCAP

168

15.4 Understanding the iCAP Output

Figure 15.11: iCAP Analysis display on the lower graph Figure 15.11 shows the typical output from the iCAP analysis. They show the results from iCAP in three graphs: •

Load (x-axis) versus Displacement (y-axis) of the simulated static load test,

•

Force in Pile (x-axis) versus Depth (y-axis) (which reflects the resistance distribution), and

•

Wave-up match (Wave-up computed vs. calculated)

Additionally, along the right hand side of the iCAP graph are the numeric results of the iCAP analysis. The Output values are listed in Section 15.5

iCAP® Operation: Understanding the iCAP Output

169

15.5 iCAP Output Quantities Table 15.1: iCAP Quantity

Description

RUC

Total Resistance from iCAP

SFC

Shaft Resistance from iCAP

EBC

End Bearing from iCAP

MQ

iCAP Match Quality

JCC

Corresponding Case Method Damping Value for that answer using RMX

CSC

Calculated maximum compressive stress from iCAP

TSC

Calculated maximum tensile stress from iCAP

BSC

Calculated compressive stress at the pile toe from iCAP

SL/BN

Save Location and Blow Number corresponding to the iCAP results shown

The user is also able to view the iCAP numeric results as Output Quantities. Adding or modifying Output Quantities is described in Section 7.1.1.

15.6 Manipulating the iCAP Scales The iCAP program will also allow the user to modify the scales on the iCAP output graphs. Below is a detailed description of all the iCAP scale buttons located on the “The CAPWAP Sub-Menu” on page 75:.

Table 15.2: Button

CAPWAP and iCAP® Sub-Menu Operation

Increase the force wave up (WU) match scale

Decrease the force wave up (WU) match scale

Increase the force scale in the F vs Depth and Ru vs Disp Graphs

Decrease the force scale in the F vs Depth and Ru vs Disp Graphs

Increase the displacement scale in the Ru vs Disp Graphs

Decrease the displacement scale in the and Ru vs Disp Graphs

iCAP® Operation: iCAP Output Quantities

170

15.7 Modifying iCAP Qualifiers It is possible to modify the iCAP program qualifiers during Data Acquisition should the user need to change these values or if an incorrect value was entered. To do so, the user will again navigate to the CAPWAP/iCAP Sub-Menu,

, and press the iCAP button,

.

15.8 Continuing iCAP Analysis During Data Acquisition Once iCAP has returned a result the program will proceed to analyze the next appropriate blow. Depending on the analysis options selected, piles types, pile length, and hardware processor speeds the program may produce an iCAP result as often as every other blow or for more complex solutions it may require additional time to complete a solution resulting in an iCAP solution every 10 to 20 blows during data acquisition. This is often generally sufficient since in most cases the capacity changes only very slowly blow by blow.

15.9 iCAP Output When a pda file that contains saved iCAP data is replayed in the PDA-S program, the iCAP results will be shown on the right hand side of the “Load” graph, but no plots will be shown. In order to show the plots, in the iCAP screen click on “iCAP Send FVOutput”. This will also show an Output Screen similar to the one from CAPWAP ® , which allows the user to generate a printout of the iCAP results (please refer to the CAPWAP on-line help for an explanation of the Output Screen features).

15.9.1 Modifying the iCAP Result The Output Screen also allows saving the iCAP results in CAPWAP-2014 format (file with extension .cww) – click on File->Save As or on the disk icon to do that. This file can then be read and further analyzed using the CAPWAP program.

15.10 PDIPlot Output In addition to viewing the iCAP results in the PDA-S program, the user is able to output these iCAP values to PDIPlot2 as PDA-S would output other typical Case Method Results.

15.11 iCAP External Inputs (BLC and LP) 15.11.1 Penetration Assumptions In PDA-S, if a blow is sent for iCAP with LP set to zero, the analysis will be done assuming an LP equal to LE minus 0.3 m (1 ft). If LP is set to any number greater than zero, that number will be used. So care should be taken if for instance an initial penetration is entered but LP is not updated during driving. If LP is entered to start, then LP should be appropriately incremented during driving to correspond to the current penetration. It is better in this case to leave LP at zero, since assuming a larger penetration will not greatly

iCAP® Operation: Modifying iCAP Qualifiers

171

affect iCAP results, but trying to analyze with very small penetrations could cause incorrect results (actually this is a common cause for the “Force in Pile” to not show any graph). In review mode, enter the blow count records into the DRIVE LOG (Section 8.4) to restore the blow number versus LP relationship.

15.11.2 Blow Count Assumptions Blow count (or set) inputs using the “CW” button will be processed according to the following rules: •

If no blow count has been entered, the data adjustment for iCAP will be made using an estimated set; this adjustment is removed immediately after the data is sent for iCAP, so the data saved on the PDA file will not have any kind of adjustment.

•

When a blow count is entered it will be used in the current blow and all subsequent blows, until it is changed by the user. The adjusted data will be kept after it is sent to iCAP, so it will be saved on the PDA file.

•

If a new blow count is entered on a record that had been previously adjusted (like for example when a new blow count is entered at the end of drive and the “Do iCAP” button is pressed, or when replaying existing data), the change will affect only the current blow.

15.12 iCAP Methodology

Figure 15.12: iCAP Flow Chart

iCAP® Operation: iCAP Methodology

172

If the PDA is set to request an iCAP analysis, the measured force and velocity data are sent to iCAP and, assuming a uniform cross section along the entire length, a continuous pile model is created. The analysis uses the method of characteristics to perform the wave propagation computations, (Likins et al, 2012). A soil model is generated with 2 m segments along the shaft, which matches the general resolution of the data, and an extra soil element at the pile toe. An initial total capacity is assigned, either from the previous solution or from the Case Method RX7 equation, and the resistance distribution along the shaft and at the toe is determined from the force and velocity prior to the first return of the input wave after reflecting from the pile toe. The search procedure is shown in Figure 15.12. A search is made to find the optimum set of standard soil parameters (JS, JT, QS, QT, etc.) for the assumed capacity. A large toe quake is then investigated if the match quality is still relatively poor, and another search is made over the standard soil parameters to find the best solution. Based on previous correlation efforts, the maximum allowed capacity is limited to avoid overestimating capacity. If the iCAP capacity is larger than this limit, the capacity is reduced and another search made on the standard soil parameters. The balance between shaft and toe resistance is investigated. Depending on if the request is for a full or limited signal matching search, or if the analysis starts fresh or uses the previous solution, the signal matching may take more or less time to reach its conclusion. When the signal matching process is complete, the results are returned to the PDA for display. The most important results are the total capacity and its distribution between shaft resistance and end bearing. Since the analysis tracks the propagating stress wave, the force at any location in the pile is determined as a function of time and the maximum compression and maximum tension forces are thus a byproduct of the process. The maximum toe force, which is useful to prevent toe damage, is also output. With the exception of timber piles, iCAP does not currently allow for non-uniform piles to be analyzed. The model also currently will not allow splices with slacks or allowance for minor tension cracking in concrete. Radiation damping, Likins, et al. (2004), is not yet considered (and thus the iCAP result generally stays on the conservative side). Options to allow these model extensions into the search are in progress.

15.13 iCAP Limitations iCAP offers automated signal matching analysis during data collection and data review. While this analysis offers capacity estimation independent of damping selection, the analysis has limitations. It should be noted that since iCAP is fully automated, its use is limited to uniform piles in normal driving conditions. Scenarios the iCAP analysis cannot accurately model are: •

non-uniform piles,

•

piles with (even minor) damage,

•

concrete piles with minor cracking,

•

piles with uncertain properties (such as bored piles)

•

Larger open-end pipes or H-piles in high friction soils (due to internal plug movements)

•

piles in unusual soils may pose extra difficulties.

The program only performs a limited data quality check. And as mentioned earlier, the iCAP signal matching procedure is not as thorough as what is done by CAPWAP and

iCAP® Operation: iCAP Limitations

173

differences in results from these two types of signal matching analyses must be expected. Preliminary studies indicate a relatively good correlation (10-15%) with CAPWAP in terms of total capacity. Comparisons of shaft resistance to end bearing have indicated higher variability and thus should be considered less reliable. Only CAPWAP has been extensively correlated with static load test results. Ultimately, the responsible engineer must check the iCAP results thoroughly. High variability of results, unrealistic damping estimations, and high match quality values may indicate poor results. It is alway advisable to compare/confirm results with CAPWAP, to determine if test results are reliable.

iCAP® Operation: iCAP Limitations

174

iCAP® Operation: iCAP Limitations

Chapter 16: SPT Data Collection

Figure 16.1: PDA-S Title Screen Units enabled with the proper licensing requirements will allow a user to collect data for SPT Energy calibration in accordance with ASTM D4633. Pile Driving Analyzer Systems enabled with SPT data collection can toggle between SPT and PDA data collection by pressing on the [SPT] or [PDA] button in the middle right of the upper row of functions.

SPT Data Collection:

176

16.1 SPT Program Notes and Considerations Please note that ASTM D4633 has requirements specific to SPT Energy calibration that differ from those encountered in the testing of piles. A few noteworthy requirements are: •

Energy calibration requires measurements at a minimum sampling frequency of 50 kHz.

•

Minimum of two accelerometers

Operation of SPT Software: •

no capacity calculation

•

streamlined file set-up

•

reporting of data made easier

•

Accelerometers must be piezo-resistive

16.2 File Set-up The user begins the file setup process by clicking the ‘Collect Wired’ button. Please note wireless data collection is not possible when the unit is in SPT data collection as the wireless signal conditioning and digitization does not conform to requirements set forth by ASTM D4633.

16.2.1 The Overview Screen Once the user has elected to collect data the user will be brought into the overview screen. This screen allows the user to view all of the pertinent file input parameters.

SPT Data Collection: SPT Program Notes and Considerations

177

Figure 16.2: Overview Screen To update a value (Rig ID, Hammer, etc.) touch or click the section of the screen which will switch to the pertinent input screen.

SPT Data Collection: File Set-up

178

16.2.2 Project Screen

Figure 16.3: Project Screen The Project Page generally contains descriptive information such as names. •

The Rig ID(PJ) - The Model (and SN) of the test rig will also double as the file folder where the data is stored

•

Depth Interval (PN) - will also double as the name of the file in which the data is saved.

•

Bore Hole (PD) - is used to denote the bore hole the data was collected on.

•

Operator Name (OP) - documents the PDA operator collecting or analyzing the data.

•

Project Directory - indicates the storage location for the file. The default location will be C:\Users\PDI\Documents\[Your Name]\PDIData\[PN]\[PN].pda

SPT Data Collection: File Set-up

179

16.2.3 Rod Model Screen

Figure 16.4: Pile Model Screen The Rod Model Screen is where the user inputs the rod's geometric and material properties necessary for accurate computations.

16.2.3.1 Geometric Properties: •

LE - the rod length from the sensors to the rod bottom.

•

LP - the current distance from reference elevation to the bottom of the boring.

•

AR - The cross sectional area of the instrumented drill rod sub-assembly.

16.2.3.2 Material Properties: Material Properties for a SPT drill string are fixed for values of steel •

EM - The Elastic Modulus (EM) of the rod material in kips/in 2 (English), Ton/m 2 (Metric), or kN/m 2 (SI). For steel, EM should be 30,000 ksi, 2109 Ton/m 2 or 206,843 MPa.

•

SP - The Specific Weight (SP) of the rod material in kips/ft 3 (English), Ton/m 3 (Metric), or kN/m 3 (SI). For steel, SP should be 0.492 kips/ft 3 , 7.88 Ton/m 3 or 77.3 kN/m 3 .

•

WS - The Wave Speed (WS) in the rod in either ft/s (English) or in m/s (Metric or SI). For steel rods the wavespeed is approximately 16,807 ft/s or 5,123 m/s.

16.2.3.3 Length Increment LI values of 0.5 ft (English units) and 0.15 m (Metric and SI), are fixed if the user chooses to enter the increments during data collection. The user may also enter these values through the drive log after data collection.

SPT Data Collection: File Set-up

180

16.2.3.4 Area Entry using Smart Sensors

Figure 16.5: SPT Rods instrumented Smart Sensors will have the area pre-programmed Instrumented SPT Rods that are programmed using smart sensor technology may have the area pre-programmed as well. In such instances, the program will automatically determine the appropriate rod area without any further input from the user. Note that in such instances the user will not be able to alter the area.

SPT Data Collection: File Set-up

181

16.2.3.5 Area Entry without Smart Sensor programming

Figure 16.6: Area may be entered directly, from standard values or the area calculator PDA-S allows the user to enter the area of the SPT rod subassembly in three different ways: •

Area by Rod - a list of common area values for various rod types included in the program. Most rod types include a ‘heavy wall’ and ‘standard wall’ section are included. The user may select the appropriate area and confirm the selection by pressing the button.

•

Area by Calculator - An area calculator has been provided to correctly determine this important parameter. To access this function during data replay, click ‘Area by Calculator’ which prompts the Area Calculator. The User enters the overall section diameter and wall thickness, and the resulting area is displayed. Click OK to accept the result and confirm the selection by pressing the button.

•

Area by Keypad - Allows the user to directly enter the cross-sectional area. In most instances the rod calibration will note the area specific to that rod. After entering, confirm by pressing the

button.

SPT Data Collection: File Set-up

182

Figure 16.7: Area Calculator for a pipe section

16.2.4 Sensor Screen The Sensor Screen is used to observe or enter the calibration values for the sensors that you are using, view balancing information, and adjust trigger levels for the sensors. Note that the PDA-S software, while in SPT mode requires the use of piezoresistive accelerometers

SPT Data Collection: File Set-up

183

Figure 16.8: Sensor Screen for wired connection The SPT Analyzer system will allow any configuration of accelerometer or strain sensor into any channel, although standards such as those published by ASTM would require at least two accelerometer channels and at least two strain channels. The current system will be labeled as channels 1 through 4 with an F or an A denoting whether each channel is a force or acceleration measurement respectively. Please note that the SPT main cable should be connected to Channel 1. It is the right most main cable connector when facing the screen, and labeled ‘1’ on the back of the unit.

16.2.4.1 Use of Smart Sensors The PDA-S program is designed for use with Smart Sensors. Attach any sensor into any channel on the connection cable. The PDA-S software will automatically detect the sensor's type, serial number and calibration value. Older Smart Sensors are able to be used but will require the wire adapter shown in Figure 2.16.

16.2.4.2 Use of Non-Smart Sensors (Old Style) The system will default each channel as unused if it cannot detect a smart sensor. Therefore if a user has connected older sensors that do not have smart sensor technology it is necessary for the user to turn on that channel by placing a check in the ‘Used’ box. If this step is not performed no data will be collected on that channel. Sensors which do not have smart sensor technology will require the user to directly enter their appropriate serial number and calibration value. After selecting the appropriate channel lacking a Smart Sensor, select the information for the traditional sensor from the sensor database, or enter the information into the database.

SPT Data Collection: File Set-up

184

Figure 16.9: Senor Database If the sensor you are using is in the list, highlight the sensor and press OK.

Figure 16.10: Adding new sensor to database

SPT Data Collection: File Set-up

185

If the sensor is not already in the list, press the NEW button (Figure 16.9) and then the sensor ID number (usually engraved on the serial number plate or on the sensor itself), and calibration (which may be found in the calibration sheet provided by Pile Dynamics), then press OK to store the new information (Figure 16.10).

16.2.4.3 Selecting Trigger Channels The TRIG column (Figure 16.8) selects which sensors will trigger the data acquisition for SPT Energy Testing. Any combination of sensors can be used for triggering the data acquisition. The Unit will continually monitor these channels (with a check in the TRIG box), until the signal level exceeds the specified thresholds (See “Trigger Levels” on page 185.). Only then will the Unit start to acquire data. It is generally recommended for SPT Energy calibration, that all active channels are selected as potential trigger channels.

16.2.4.4 Active Channels The Active column (ACT) they will not be averaged still be collected if USED least two accelerometers tests.

allows deactivating channels that are not being used, so that with the other acceleration or force signals. Data will normally (Section 16.2.4.5) NOTE: it is strongly recommended that at and at least two strain channels are active on all SPT Energy

16.2.4.5 Used Channels If a channel does not have a sensor attached, that channel should be deactivated (remove the check mark in the USED box) and no data will be recorded on that channel.

16.2.4.6 Trigger Levels The TRIGGER column is used for changing the minimum trigger levels on each gage. If these threshold trigger levels are too high then the unit will not trigger: that is, it will not accept and therefore not display any blow data upon a new hammer impact, even though the unit is in Accept mode.

16.2.4.7 Sensor Balancing Sensor balancing has been incorporated into the Sensor set-up page. If the sensor is balanced no further assessment is required and the system can proceed into data collection. If however a sensor is ACTIVE and USED yet unbalanced then the unit will not be allowed to proceed into data collection. The unbalanced sensor will be indicated by a large red X over the sensor serial number. The user must either connect or replace that sensor (or deactivate that channel) before proceeding into data collection mode.

SPT Data Collection: File Set-up

186

16.2.5 Hammer Selection Screen

Figure 16.11: Hammer Selection screen The hammer used can be documented by entering the hammer type, energy rating and ram weight. Note that when in SPT mode, the PDA-S program assumes the standard ram weight of 140 lbs (65 kg) and potential energy of 350 ft-lbs (475 Joules). The user may modify the Maker, Name, Ram weight, and Drop Height, by touching the corresponding labels and the corresponding energy will be calculated based on the Ram Weight and Drop Height. There is also a Max BPM (Blows Per Minute) entry field. The value entered should correspond to slightly higher than the maximum manufacturer's operating rate for the hammer which typically ranges between 40 and 60 blows per minute for SPT autohammers. This will prevent the unit from triggering on false blows due to hammer bounces. The Maximum Blow Rate will be limited based on sample time and data collection frequency.

SPT Data Collection: File Set-up

187

16.2.6 Data Sampling Screen

Figure 16.12: Data Sampling screen The Sampling screen (Figure 16.12) allows the user to choose the sampling frequency and the total sample time for each blow. The analog signals are converted to digital data at a rate defined by the Sample Frequency. Total collected time intervals of either 100, 200 milliseconds may be stored for each signal, as selected under Sample Time. The total number of data points that will be stored is shown in the box under Pretrigger Buffer Time and is a function of the Sample Frequency and of the Sample Time. For example, if 200 ms are selected at a frequency of 50,000 Hz, then a total of 10,000 data points will be stored. Table 16.1 shows the available sampling sizes and frequencies, and the corresponding total record durations.

Table 16.1: SPT Data Sampling Options

Time Increments

Sample Size for selected frequency and time increment 100 kHz

50 kHz

100 ms

10000

5000

200 ms

20000

10000

The resulting file size will be larger for higher frequencies and longer total time samples.

SPT Data Collection: File Set-up

188

16.2.6.1 Pretrigger Buffer The Pretrigger Buffer Time specifies the amount of data that will be recorded, corresponding to the information detected by the sensors just prior to triggering. The Pretrigger Buffer Time is fixed at 10 ms for the SPT Program.

16.2.7 Data Limits The data limits tab allows the user to define a series of minimum and maximum thresholds for a variety of quantities. If a quantity passes the threshold, a series of warnings embedded in the data acquisition and review screens will be triggered, as described “Assessing Data Quality” on page 97

16.2.7.1 Velocity Limits

Figure 16.13: Velocity Limits The limits on End Velocity should be tolerant of some error and values of +1.0 m/s and 1.0 m/s (+/- 3 ft/s) are recommended as reasonable. The limits on End Displacement should be set to about +300 mm and -10 mm (+12 to -0.5 inches, respectively) to assure the displacement is within a reasonable range. Indicator lines can be toggled on displays with velocity or displacement by checking the box under the ‘Display Line?’ column.

SPT Data Collection: File Set-up

189

16.2.7.2 Energy Limits

Minimum and maximum energy limits may be valuable for detecting poorly operating hammers and insuring minimum and maximum performance. These limits vary but auto hammers generally yield transfer efficiencies from 60 to 90% depending on the hammer. Transfer efficiencies greater than 100% are generally related to the auto hammer over stroking or potential data quality issues. The maximum energy can be displayed on graphs including energy by checking the box in the ‘Display Lines?’ Column.

SPT Data Collection: File Set-up

190

16.2.7.3 Hammer Stroke / Rate

Figure 16.14: Hammer Stroke / Blow Rate Limits Limits may be set for the hammer blow rate. Typical blow rates for an SPT auto-hammer generally vary by hammer manufacturer.

16.3 Proceeding to Data Collection Once all the appropriate information has been entered the user may proceed into data collection by pressing the ‘Collect’ button at the bottom of the screen. If there are any issues that prevent data collection, such as non-unique pile names, unbalanced sensors, maximum blow rates out of range, or others, a message will appear across the bottom of the setup screen and data collection cannot proceed until the problem is resolved.

16.3.1 Data Validation Screen The Data validation screen will note which parameters should be reviewed prior to going into data collection mode (Figure 16.14).

SPT Data Collection: Proceeding to Data Collection

191

Figure 16.15: Data Validation Screen will notify the user of potential set-up errors before proceeding to data collection

16.4 Program Operation Operation of the PDA-S program while in SPT mode will be identical to operation of the PDA-S program as outlined in “Basic Program Operation” on page 59. The two major differences are: •

The iSTART /iSTOP button as well as the CAPWAP submenu will not be available on the Operations Toolbar as SPT data cannot be analyzed for capacity.

•

The user will not be able to call any Output Quantities that relate to capacity (such as RX9, RA2, etc)

Please note that the PDA-S program in SPT mode was designed solely for collecting data for SPT Energy calibration and as such, data collected while in SPT mode cannot be analyzed for capacity which includes exporting files to CAPWAP

®

®

or iCAP .

16.5 Data Analysis Data analysis for SPT Energy calibration generally is minimal as the user should never apply any Replay Factors to SPT records. It is generally recommended that the user apply time shift corrections (Section 8.2.1 on page 100) and enter the observed blow counts through the drive log (Section 8.4.1 on page 104) before reporting results. Proportionality should never be used as an accurate assessment of data quality for SPT testing as non-uniformities of the rod, potential loose joints, and possibly differing rod sections would all have a significant effect. General guidelines for assessing SPT data would be similar results from individual measurements showing general stability of the data without any electrical noise.

SPT Data Collection: Program Operation

192

16.6 Report Generation The PDA-S software, when in SPT mode, has the ability to create detailed reports from collected PDA-S files and to summarize results for reporting purposes quickly and easily.

16.6.1 Creating an SPT Report An SPT report may be created by first merging all files from the same bore hole into one file (as described in Section 8.10.1 on page 115). It is generally recommended that the user enter the blow count values through the drive log for individual depth increments and then merge the files together, though if the user chooses to merge files and then enter the drive log they may do so. The user should merge the files such that they are sequentially increasing in depth and time increment. Once the files have been merged and drive logs have been entered (if desired) the user may enter the report set-up window through the ‘Functions” Menu and selecting ‘Report’.

Figure 16.16: Report Set-up Window The report setup window allow the user to define the output quantities that will be included in the report as well as which depth intervals are included in the report.

SPT Data Collection: Report Generation

193

16.6.1.1 Defining Sample Intervals A user may define the sampling intervals by depth or by blow number. For instance, a user collects data from three separate depths 8.5 - 10 ft, 13.5 - 15 ft and 18.5 - 20 ft with blow counts of 3-5-5, 5-7-9, and 5-7-7, respectively. If the user chooses to define the sample intervals by depth, the user would go to the first table titled ‘Define the Sample Intervals to Report’ and under row one (interval one) enter 8.5 in the ‘Depth From’ column and 10 ft in the ‘Depth To’ column. Once entered a new row will be created underneath the first and the data for the next sample interval may be entered in the following row: 13.5 in ‘Depth From’ and 15 in ‘Depth To’ for interval(row)2, and finally for interval (row) 3 18.5 in ‘Depth From’ and 20 in ‘Depth To’. Alternatively, if the user chooses to define the intervals by blow number, the user would start in interval (row) 1 in the ‘BN from’ column entering 1 and in the ‘BN To’ column entering 13. The following intervals would be defined as 14 and 34 in the ‘BN From’ and ‘BN To’ columns for interval (row) 2 and 35 to 53 for interval (row) 3.

16.6.1.2 Validating Sample Intervals Once the user has defined the sample intervals they may click the ‘Validate’ button to verify that all the intervals defined have blows within those depths (or blow number range) and, if there are any discrepancies, the program will notify the user.

16.6.1.3 Deleting Sample Intervals In the instance the user would like to exclude a defined sample interval from reporting, the user may delete the interval by clicking on any cell in the sample interval row and clicking ‘Delete Interval’. This may be useful if a sample, which has previously merged with a file, needs to be removed from the reporting and overall average because of insufficient samples in an interval or questionable results.

16.6.1.4 Auto-Defining Sample Intervals Sample intervals may be auto-defined based on time lapses occurring between sampling. The user may define the time lapse between sample intervals in the ‘Auto-Detect Time Between Sample Intervals’. The default values is 10 minutes, the user may increase or decrease this value by looking at the time stamps embedded on each blow between sample intervals and adjusting to an appropriate value.

16.6.1.5 Defining Headers in Reporting The user may choose to include or exclude the blow number (BN), length of penetration (LP), blow count (BLC), and elevation (EL). The last 3 require manual entry of the drive log either during data collection or in data review mode through the drive log. The user may select the desired headers by clicking and dragging the values into the ‘include’ column, or remove them from the report by clicking and dragging the quantity into the ‘exclude’ column. The user may also reorder the headers into the desired order of presentation by clicking and dragging the quantities up or down the ‘include’ list.

16.6.1.6 Defining Output Quantities The user may choose to include or exclude the certain ‘Output Quantities’ into the report, such as EFV, the maximum transferred energy. The user may select the desired output quantities by clicking and dragging the values into the ‘include’ column, or remove them from the report by clicking and dragging the quantity into the ‘exclude’

SPT Data Collection: Report Generation

194

column. The user may also reorder the quantities into the desired order of presentation by clicking and dragging the quantities up or down the ‘include’ list. The user is limited to a total of twelve columns between the headers and output quantities selected. If the number of quantities exceeds twelve the user must drag output quantities or header values into the ‘exclude’ columns until there are a total of twelve or fewer.

16.6.2 Reporting Options The ‘Reporting Options’ menu allows the user to include or exclude various information from the report.

Figure 16.17: Reporting Menu Options The Legend defines all output values from their two or three letter abbreviation. The user may •

Do Not Print Legend - excludes the legend defining the displayed header and output quantities.

•

Print Legend at Top - prints the legend above the table for each sampling interval.

•

Print Legend on Every Page - prints the Legend at the top of every page (should there be multiple pages of output quantities for one interval)

SPT Data Collection: Report Generation

195

The SPT Report has the ability to create a Force Velocity plot for each sample interval. •

Print Rod Data on Every Page - When selected, the rod material and geometric properties (AR, LE, EM, SP, WS) will be summarized at the top of every page.

•

Print Project Data on Every Page - When selected, the project information (PN, PJ, and PD) will be summarized at the top of every page.

•

Included F/V Graph - When selected the output will include a F/V graph for every sample interval. Please note that the scaling on the output will mimic those of the graph in the data collection screen. Any adjustments to the time scale or vertical scales should be done prior entering reporting mode. If any adjustments to the scaling are required, the user will need to exit the report mode and make the appropriate corrections.

When reporting results from a sampling interval it is generally recommended to report the output quantities for the second and third six inch (0.15 m) depth interval and in some instances specified. The data from the second and third depth interval will always be included into the averaging for each sample interval. The user may wish to include data from the entire sample interval. Note that all data collected for a sample interval will be displayed; data excluded from the average for a sample interval will be presented in a light gray font. •

Include First Section - will include the data from the first six inches (0.15 m) in the interval average.

•

Include Fourth Section - In cases where a fourth six inch sampling increment is included in a depth interval, a user may include that by selecting ‘Included Fourth Section’. If not selected the data will be displayed in gray but will not be included in the overall average.

•

Start Interval on New Page - When selected, places a page break between each depth interval.

In addition to including or excluding data from statistical analysis the user may determine which statistical information is presented at the bottom of each sample interval: •

Show Interval Average - When selected, shows the average value for each Output Quantity at the bottom of each depth interval.

•

Show Interval Maximum - When selected, shows the maximum value for each Output Quantity at the bottom of each depth interval.

•

Show Interval Minimum - When selected, shows the minimum value for each Output Quantity at the bottom of each depth interval.

•

Show Interval Standard Deviation - When selected, shows the standard deviation value for each Output Quantity at the bottom of each depth interval.

•

Show Interval Comments - When selected, it will display any PC comments applied to any blow over that depth interval.

•

Show Interval Time Summary - When selected, in will display a time summary for a depth interval based on the time stamp from the collected data.

•

Show Overall Summary - When selected, table summarizing the averages from all sample intervals will be created showing overall statistics for all sample intervals.

SPT Data Collection: Report Generation

196

•

Narrow F/V Graph - When selected, the F/V graph will be plotted on a narrower field allowing for more rows of data on the table in one page.

•

Add Rod Length to Overall Summary - When selected, the rod length (LE) will be included for each sample interval.

•

Suppress Page Numbers - When selected, page numbers will not be displayed in the report.

16.6.2.1 General Options

Figure 16.18: General Options The User can choose to return to the report setup page once a generated report is closed or go back to the main data screen (i.e. the report setup window will automatically close).

16.6.3 Creating a Report Once the user has defined the desired sample intervals, Output Quantities and reporting options, a report can be generated by clicking the ‘View’ button. The program will then generate a report and open a new window.

SPT Data Collection: Report Generation

197

Figure 16.19: SPT Report showing the first sample interval The user may navigate through the report by clicking the up or down arrows in the upper right hand corner of the window.

Figure 16.20: Overall Statistics from the SPT Report The user may then print the file by clicking on the printer icon.

SPT Data Collection: Report Generation

198

SPT Data Collection: Report Generation

Chapter 17: Recommended Resources A vast array of information can be found on our website (www.pile.com) which include a FAQ section, product specifications, sample project specifications and a technical library. While it would be non-productive to list every resource we highlight a few that have particular interest to dynamic testing.

17.1 Sample Project Specifications •

High Strain Dynamic Testing of Driven Piles

•

High Strain Dynamic Testing of Drilled and Cast-in-Place Shafts

17.2 Technical Papers 17.2.1 Correlation Studies •

Likins, G. E., Rausche, F., August 2004. Correlation of CAPWAP with Static Load Tests. Proceedings of the Seventh International Conference on the Application of Stresswave Theory to Piles 2004: Petaling Jaya, Selangor, Malaysia; 153-165. Keynote Lecture

•

Likins, G. E., Rausche, F., Thendean, G., Svinkin, M., September 1996. CAPWAP Correlation Studies. Proceedings of the Fifth International Conference on the Application of Stress-wave Theory to Piles 1996: Orlando, FL; 447-464.

•

Rausche, F., Hussein, M.H., Likins, G. E., Thendean, G., June 1994. Static Pile LoadMovement From Dynamic Measurements. Proceedings of Settlement '94; Vertical and Horizontal Deformations of Foundations and Embankments: College Station, TX; 291-902.

Recommended Resources: Sample Project Specifications

200

17.2.2 General Overview •

Hussein, M.H., Likins, G. E., May 1995. Dynamic Testing of Pile Foundations During Construction. Proceedings of Structures Congress XIII: Boston, MA; 13491364.

•

Likins, G. E., Rausche, F., February 2014. Pile Damage Prevention and Assessment Using Dynamic Monitoring and the Beta Method. From Soil Behavior Fundamentals to Innovations in Geotechnical Engineering. ASCE Geo-Institute Geotechnical Special Publication No. 233: Reston, VA; 428-442.

17.2.3 Integrity Analysis

17.2.4 Soil Set-up/Relaxation •

Hussein, M.H., Likins, G. E., Hannigan, P., May 1993. Pile Evaluation by Dynamic Testing During Restrike. 11th Southeast Asia Geotechnical Conference: Singapore; 535-539.

•

Hussein, M.H., Likins, G. E., October 1995. High-Strain Dynamic Testing of Drilled and Cast-In-Place Piles. Deep Foundations Institute 20th Annual Members Conference and Meeting: Charleston, SC; 127-142.

•

Likins, G. E., Liang, L., Hyatt, T., September 2012. Development of Automatic Signal Matching Procedure - iCAP®. Proceedings from Testing and Design Methods for Deep Foundations; IS-Kanazawa: Kanazawa, Japan; 97-104.

17.2.5 Bored Foundations

17.2.6 iCAP

17.3 Product Specifications •

Pile Driving Analyzer System Specifications (Model 8G)

•

Piezoelectric Accelerometer Specifications

•

Piezoresistive Accelerometer Specifications

•

Strain Sensor Specifications

•

Wireless Transmitter Specifications

Recommended Resources: Product Specifications

Appendix A: The Case Method, Wave Mechanics, Theory and Derivations A.1 Foreword In order to understand how the PDA calculates certain quantities from pile top force and velocity measurements it is necessary to understand the underlying theory. The best way to study the underlying theory is with the treatment found in Timoshenko’s Theory of Elasticity (note references can all be found on www.pile.com) which is a summary of closed form solutions and examples developed by various mathematicians in the 19 th century. These closed form solutions have been applied to the Case Method measurements. The collection of formulas and equations developed for the purpose of calculating soil resistance, pile stresses, hammer performance parameters, pile integrity factors and other quantities are all part of the Case Method which was developed during the late 1960s and 1970s both at Case Western Reserve University and Pile Dynamics. Besides looking at the papers and books referenced in this description, ample references contained in www.pile.com are recommended reading for the PDA user. Furthermore, the user should be familiar with ASTM D4945, latest edition. The following derivations of wave speed and proportionality are not strictly correct in a mathematical sense. They should be understood as an illustration of the basic wave propagation process and should provide the reader with a “feel” as to what is happening in a pile when it is struck by a rigid mass. All formulas of the Case Method were derived on the assumption of a uniform (constant area, elastic modulus and mass density), linearly elastic rod whose length is much greater than its diameter or width. We may sometimes violate these requirements in actual piling situations and we then should try to evaluate how large an error may result. This document uses a variety of symbols and 2-letter codes for various material and other pile properties. In derivations we will represent with Greek letters certain material

The Case Method, Wave Mechanics, Theory and Derivations:

202

properties while for actual problem solving we may show the PDA 2-letter codes. The following are traditional and PDA symbols frequently encountered in this document.

Table A.1: Common Symbol

PDA Symbol

SI Units

US Units

Elastic Modulus

E

EM

MPa

Ksi

Specific Weight



SP

kN / m3

lbs / ft3

Wave Speed

c

WS

m/s

ft / s

Cross-sectional Area

A

AR

cm2

inch2

Mass density



-

kg (N s2 / m)

kips s2 / ft

Name

A variety of subscripted symbols are used to represent the various dynamic quantities and in the mathematical formulations; however for certain values of these curves, the PDA uses 3 letter acronyms for output description. Important quantities are listed in the following table (additional quantities can be found in the PDA’s “Quantity” listing.

The Case Method, Wave Mechanics, Theory and Derivations:

203

Table A.2: Quantity description (units)

Force (kN, kips)

Representation in Equations

F(t)

Related PDA Quantities

Related PDA output acronyms

Max. Force,

FMX,

Force at time 1, 2

FT1, FT2

Acceleration (g’s)

a(t)

Max. Acceleration

AMX

Velocity (m/s, ft/s)

v(t)

Max. velocity

VMX,

Velocity at time 1, 2

VT1, VT2

Strain (10 -6 )

(t)

Max. Strain

MEX

Stress (MPa, ksi)

(t)

Max. Measured Compressive Stress

CSX

Wave-down (kN, kips)

F d (t), F d1

Force in Wave-down at time 1

WD1

Wave-up (kN, kips)

F u (t), F u2

Force in Wave-up at time 2

WU2

Displacement inch)

u(t)

Max. Displacement

DMX,

Displacement at end

DFN

(mm,

Transferred (kJ, ft-kips)

Energy

Et

Max. transferred energy

EMX

Transferred Ratio (1)

Energy

nt

Transferred Energy Ratio (or efficiency)

ETR

The Case Method, Wave Mechanics, Theory and Derivations:

204

A.1 The Wave Speed Consider a rod that is suddenly loaded by a force, F , creating a stress wave to travel down the pile at wavespeed, c . The particles are at rest at time t , just before an impact occurs. Suppose then a short time, t , later, the impact force has compressed a portion of the pile top having length L .

time t

time t+Δt

F

P

F Δu P ΔL

Figure A.1: As a compression stress wave encounters a particle the particle is deformed in compression and displaced down the pile Since L has been compressed within a time t , we consider the speed with which the pile top has been compressed the wave speed c , where c = L ------t

eqn A.1.1

Because of the compression, point P, has moved a distance, u . The displacement, u , being the result of compressing the rod with the impact force F over a distance L can be computed from rod cross-sectional area, A , and elastic modulus, E , as: u = FL ----------EA

eqn A.1.2

The velocity of the point P pile particle, actually its change of velocity due to force F , is called the particle velocity, v . It can be calculated from the deformation u divided by the time increment during which it occurs.

The Case Method, Wave Mechanics, Theory and Derivations: The Wave Speed

205

v = u ------t

eqn A.1.3a

Combining eqn A.1.2 and eqn A.1.3a the change of particle velocity can be calculated from F L v =  --------  ------- EA t

eqn A.1.3b

And remembering eqn A.1.1 we obtain Fc v = -------EA

eqn A.1.3c

Since this velocity was achieved during time period t , we can also calculate the acceleration of our particle. v a = ----t

eqn A.1.4a

Fc a = ------------EAt

eqn A.1.4b

or

Using Newton’s Second Law, which is F = ma

eqn A.1.5a

and knowing that the accelerated mass at the point is equal to the product of the mass density of the pile material,  , the cross sectional area, A , and the compressed pile length, L , OR m = AL , the force can now be written as  AdL Fc F = --------------------------EAt

eqn A.1.5b

After canceling the A and F terms and remembering that  L    t  is the wave speed c, we obtain 2 c = E --

eqn A.1.6

Thus, we have found that the wave speed, c , depends only on the pile material properties and not, for example, the frequency of the applied force (admittedly though this is only true for our simplifying assumptions of a very slender, elastic rod) In summary, let us remember that 1 The “Wave Speed” is the speed with which a compression (or tension) wave (or zone) moves along a rod. 2 The “Particle Velocity” is the speed with which a particle in a rod moves as a wave passes by.

The Case Method, Wave Mechanics, Theory and Derivations: The Wave Speed

206

Example Problem 1: Wave Speed a Calculate the wave speed for concrete with a dynamic elastic modulus of 35,000 MPa (5,000 ksi) and unit weight = 24 kN/m 3 (150 lb/ft 3 ). Repeat the calculation for b timber (E = 12,000 MPa or 1,800 ksi and = 8 kN/m 3 or 50 lb/ft 3 ) c and steel (E = 210,000 MPa or 30,000 ksi and = 77 kN/m 3 or 492 lb/ft 3 ).

The Case Method, Wave Mechanics, Theory and Derivations: The Wave Speed

207

A.2 Proportionality and Pile Impedance Let us again consider the uniform elastic rod and a stress wave traveling along its length at wave speed, c . If the force at the wave front is F , we noted in the previous section, eqn A.1.3b, that the change of particle velocity and v =  du    dt  can be expressed as a relationship between the force and the particle velocity in a stress wave: Fc v = ------EA

eqn A.2.1

v = c -----E

eqn A.2.1a

v = c

eqn A.2.1b

or in relationship to stress

or in relationship to strain

These relationships express a proportionality between the particle velocity v and either applied force or stress or strain. The proportionality factors are composed of pile material properties A , E , c and/or  . While we normally use velocity, v , in these expressions, it is important to remember 1 That the force really caused an increase of velocity (if the velocity was not zero before impact) and 2 that this proportionality only holds if no effects other than one wave traveling in a given direction is present. The inverse of the proportionality constant, c/EA, is Z = EA -------c

eqn A.2.2a

which is also called the pile impedance. This term implies that rod offers a resistance to (impedes) the change in velocity. In fact, the impedance (which has the units of force divided by velocity) is that force which changes the pile particle velocity by 1 m/s (ft/s) Note the following alternate forms of impedance. 2

For example, by replacing E in eqn A.2.2a with c (eqn A.1.6) we obtain Z = cA

eqn A.2.2b

M or after replacing A with the pile mass per unit length ----L Z = Mc -------L

eqn A.2.2c

The Case Method, Wave Mechanics, Theory and Derivations: Proportionality and Pile Impedance

208

Example Problem 2: Impedance Compute the impedance of a pile for a 27.5 cm (11 inch) square concrete pile of 30 m (100 ft) length using concrete properties in Example Problem 1. Do the computations for all three equations 2.2 a, b and c.

The Case Method, Wave Mechanics, Theory and Derivations: Proportionality and Pile Impedance

209

A.3 Basic Wave Mechanics A.3.1 The Wave Equation

u

x Figure A.2: The pile displaces downward as the stress wave travels down the pile The foregoing considerations can be put in a stricter mathematical form (from Hooke’s and Newton’s Laws) leading to the one-dimensional wave equation: 2



u t

2

2

= E

u x

2

eqn A.3.1

where u is the rod displacement at time t and location x and where the left and right hand partial derivatives are the acceleration and strain in the rod, respectively. This equation is referred to as the linear one-dimensional wave equation which has a general solution u = f  x – ct  + g  x + ct 

eqn A.3.2

which implies that a displacement pattern in the rod may consist of two components, g and f . Note that the f displacement pattern will have the same argument if, for increasing times t + t , the x-coordinate increases by ct ; similarly the g pattern will have the same argument if, for increasing times t + t , the x-coordinate decreases by ct .

The Case Method, Wave Mechanics, Theory and Derivations: Basic Wave Mechanics

210

f  x – ct  = f  x + cdt  – c  t + dt 

eqn A.3.3a

g  x + ct  = g  x – ct + c  t + t  

eqn A.3.3b

and

time t

f

time t+Δt c't f g

g

x

c't

Figure A.3: The displacement pattern of a slender rod consists of and upward and downward traveling component Thus, the g and f displacement patterns have merely shifted downward (positively) and upward (negatively) along the pile as time increases. They shift at a speed c as seen before. We will, therefore call the two traveling displacement patterns a downward wave and an upward wave. Since the particle velocity, v , and the acceleration, a , are time derivatives of the displacement, the velocity and acceleration patterns are also downward and upward traveling waves. Similarly, since the strain, stress and force can be derived from the displacement pattern by derivative with respect to x , these three quantities also do not change pattern as they shift upward or downwards along the pile. The solution to the wave equation shows also that the total particle displacement, and therefore all of its derivatives, is the sum of the displacements in the upward and the downward wave. Thus, Displacement: u = u d + u u

eqn A.3.4a

Velocity: v = v d + v u

eqn A.3.4b

Acceleration: a = a d + a u

eqn A.3.4c

The Case Method, Wave Mechanics, Theory and Derivations: Basic Wave Mechanics

211

Strain:   =  d +  u

eqn A.3.4d

Stress:  =  d +  u

eqn A.3.4e

Force: F = F d + F u

eqn A.3.4f

If we apply these findings to piles during impact, then we may get the following situation (assuming no soil resistance).

time t

time t+Δt

F

F

cΔt

Figure A.4: The compression wave, induced by the hammer at the pile top, moves downward a distance ct during the time interval t Remember that within the initial downward input wave, there are compressive forces, causing proportional downward directed particle velocities. Let us designate the forces and velocities in the downward wave with the subscript “d” and write the proportionality condition as: F d = Zv d

eqn A.3.5

The Case Method, Wave Mechanics, Theory and Derivations: Basic Wave Mechanics

212

time t

time t+Δt

F

F

Figure A.5: The compression wave arrives at the pile toe where it is reflected After a time L  c ( L is the pile length), the impact wave caused by the pile driving hammer arrives at the pile bottom where it is reflected. An example for a wave induced by a pile driving hammer is shown in the above figure. We will study what happens at the time of wave reflection a little later. As we will see in more detail, an upward traveling tension wave has a downward directed particle velocity (like the downward traveling compressive wave), which means that on a free pile bottom, the velocity (and thus the displacement and acceleration) doubles while the forces cancel each other. The initial compression wave pushes the pile down while the reflected tension wave pulls the pile down. Thus all motion is in the downward direction.

A.3.2 Upward and Downward Traveling Waves We now define a sign convention: • Compressive forces, stresses, strains are positive • Tension forces, stresses, strains are negative • Downward directed particle velocities, displacements, accelerations are positive • Upward directed velocities, displacements, accelerations are negative. Consider an impact against the bottom of the pile. It will generate an upward traveling compressive wave (positive) with upward directed (negative) particle velocities, while an applied tension (negative) wave pulls the pile particles in a downward (positive)

The Case Method, Wave Mechanics, Theory and Derivations: Basic Wave Mechanics

213

direction. Thus for upward traveling waves the proportionality condition includes a minus sign. Upward traveling waves, therefore, have a particle velocity that is negative (upward) for positive (compression) forces and positive (downward) for negative (tension) forces. Thus, for upward traveling waves Fu = –Z vu

eqn A.3.6

The total force, F , and velocity, v , measured at any location is the total force and total velocity at the measurement point and, as we have seen in the general solution to the basic wave equation, they are the result of superposition of the forces and velocities in the downward and upward traveling waves. F = Fd + Fu

eqn A.3.7

v = vd + vu

eqn A.3.8a

and

If the velocities are converted to forces by multiplication with the impedance

Z ,

eqn A.3.8a becomes Zv = F d – F u

eqn A.3.8b

which can be combined with eqn A.3.7 to solve for the forces (and thus also velocities) in the upward and downward traveling waves. F + Zv  F d = --------------------2

eqn A.3.9a

F – Zv  F u = -------------------2

eqn A.3.9b

and

In other words, if we measure the force, F , and the velocity, v , at a point of the pile, then the force in the downward traveling wave at that point can be determined from the average of force, F , and velocity times impedance, Zv .Similarly, the force in the upward traveling wave can be determined from one half of the difference between force, F , and velocity times impedance, Zv . By proportionality we also find that Z+v vd = F -------------------2

eqn A.3.10a

FZ+v v u = –----------------------2

eqn A.3.10b

and

The Case Method, Wave Mechanics, Theory and Derivations: Basic Wave Mechanics

214

A.3.3 The Classical Reflection Model

Real Pile

The type and magnitude of the reflection depends on the type of resistance at the pile bottom. Let us first consider the simple case of a free pile bottom. If the compressive wave arrives at a free pile bottom an imbalance exists since the wave has no pile mass to accelerate and no pile material to strain; therefore a reflection occurs. Because the pile end is free, the force at that point must be zero. The classical way to look at what happens at the free end of a pile when the compressive wave arrives is described in the following figure.

Virtual Pile

Free End no Force

Figure A.6: Free End Wave Reflection On the left we see the compressive wave moving downward in the real pile. At the same time a wave is assumed to travel upwards in an imaginary ‘virtual pile’. The two waves will arrive at the same time at the real pile bottom. In order to satisfy the condition of no force at the pile bottom, the upward traveling wave has to be a tension wave which moves the particles downward. So after the reflection is finished, there is an upward traveling tension wave in the real pile which has downward directed particle velocities. Putting these considerations in equation form, if the pile bottom is free (in other words, if there is no resistance force acting at the bottom and the resistance R = 0) from superposition we obtain Fd + Fu = 0

eqn A.3.11

Therefore, the force in the upward traveling wave is equal and opposite the downward traveling incident wave. Fu = –Fd The associated velocities are

The Case Method, Wave Mechanics, Theory and Derivations: Basic Wave Mechanics

eqn A.3.12a

215

F –F v u = ---------u = -----d- = v d Z Z

eqn A.3.12b

2F v = v d + v u = ---------d Z

eqn A.3.12c

And therefore

In other words the velocity at the bottom will be twice the velocity in the downward (or upward) wave. If we now consider a pile encountering a rigid pile bottom support, then the pile bottom condition is one of zero motion (velocity, displacement, acceleration). Thus when the compressive wave arrives at the bottom, the reflection wave has to have an upward directed (negative) particle velocity (so that the velocities cancel). The proportionality condition for the upward traveling requires a negative sign and we therefore get an upward traveling compressive force (positive) wave.

The Case Method, Wave Mechanics, Theory and Derivations: Basic Wave Mechanics

216

Example Problem 3: Example Problem 3: Wave-down and Wave-up Values Force Velocity

t1

t2

Given force and velocity at the pile top of a square prestressed, precast concrete pile (see figure above), what is the magnitude of both the downward and upward traveling wave forces at both times, t 1 and t 2 given the following values:

SI

English

Elastic Modulus

42,000 MPa

6000 ksi

Square Pile Width

610 mm

24 in

Specific Weight

24 kN/m3

150 pcf

Force at t1

4000 kN

900 kips

Force at t2

-200 kN

-50 kips

Velocity at t1

1.0 m/s

3.3 ft/s

Velocity at t2

1.0 m/s

3.3 ft/s

(Note, force and velocity values were rounded and cannot be exactly scaled in the figure).

The Case Method, Wave Mechanics, Theory and Derivations: Basic Wave Mechanics

217

A.4 Soil Resistance Assessment A.4.1 Resistance Waves Suppose that an impact wave has reached a point along the pile which is located a distance x below the top. The impact wave reaches that point at a time x  c after the impact. The soil responds to the pile’s sudden downward motion, caused by the impact wave, with a sudden upward directed resistance force R . This shaft resistance force R is a concentrated passive force representing the unit resistance times the pile perimeter times a certain length increment x . Note that R is a passive force, i.e., it acts against the direction of motion and only while the pile is moving (residual stresses are ignored at this point). The suddenly applied force R creates upwards and downwards traveling waves above and below. The two waves add their force and velocity effects to the impact wave (superposition). The two resistance waves each have a magnitude R  2 . To satisfy equilibrium and continuity, the upward wave is in compression and the downward wave in tension. Both waves (generated by the resistance R ) therefore have an upward directed particle velocity satisfying the continuity condition at x (the pile does not tear apart). The forces in the waves together balance R , satisfying the equilibrium condition; the compressive wave pushes downward above the resistance force application; the tensile waves pulls downward underneath the force application.

Upward Travelling Compression Wave Fur=R/2; vur=-R/2Z

'x

x

Ri Downward Travelling Tension Wave Fdr=-R/2; vur=-R/2Z

Figure A.7: Again, the forces and particle velocities in the upward and downward resistance waves are: R F dr = –-----2

eqn A.4.1a

The Case Method, Wave Mechanics, Theory and Derivations: Soil Resistance Assessment

218

F ur = R --2

eqn A.4.1b

R v dr = –-----2Z

eqn A.4.1c

R v ur = –-----2Z

eqn A.4.1d

which means that the forces are compression and tension to balance the resistance force and the particle velocities are directed upward (negative) in either wave to maintain continuity. The end bearing, R b , is a force applied at the pile toe and therefore generates only a single, upward traveling compression wave with upward directed particle motions. Since the end bearing is only activated by the impact wave at time L  c , its effect will be felt at the pile top only a time 2L  c after impact.

A.4.2 Shaft Resistance from Force-Velocity Difference Of course, we can divide the pile in many sections, each having a concentrated shaft resistance force, however, in the following we will only consider one shaft resistance force R i located at x as representative of all shaft resistance forces. The upward traveling compressive shaft resistance wave caused by R i reaches the pile top at time t = 2x  c after the impact. The tensile resistance wave reaches the pile bottom together with the impact wave at time t = L  c where it is reflected in compression while the impact wave is reflected in tension. Both the original tension wave from the shaft resistance waves, now compressive, and the impact wave, now tensile, are joined by the end bearing compressive wave and all three waves then travel upward to the top where they arrive at time t = 2L  c . This process is illustrated in the Depth-Time (x-t) plot below. Note that compressive and tensile waves are represented by solid and dashed arrows, respectively, and that the waves due to impact, shaft resistance and end bearing are distinguished with blue, orange and red colors, respectively.

The Case Method, Wave Mechanics, Theory and Derivations: Soil Resistance Assessment

219

L/c Fd,1

Ri (assumes a fixed pile top) 2L/c ½Ri

-Fd,1

½Ri

x

t

½Ri Rb

L Ri -½Ri

Rb Figure A.8: Wave path as resistance is activated in the pile. If we assume a fixed pile top (velocity is prescribed), then forces in the upwards traveling resistance wave have to be met by a downward traveling compressive wave so that there is no change in velocity at the pile top. Therefore, the pile top force will suddenly increase by a magnitude R i  Z , relative to the pile top velocity times impedance, vZ , before time 2L  c . (Note that we could also have assumed a free top in which case the forces would have to cancel and the velocities would double leading to a sudden negative velocity change at the pile top of magnitude – R i  Z relative to the pile top force, F ). In any case, upon arrival at x  c , the upward traveling compressive shaft resistance wave causes a separation of the pile top force and velocity (times impedance, Z) curves by an amount R i . Actually the foregoing consideration is also valid even if the measurements are not made at the pile top. Consideration of the upward compressive resistance wave of magnitude R i  2 , having an upward particle velocity equal to – R i  2Z gives a total difference between the force and proportional velocity of R i = R i  2 –  – R i  2Z Z . Therefore it is not an assumption or requirement of the Case Method that measurements be taken at the pile top. Since we are measuring both F and v , we can separate upward from downward waves at the point of measurements. In fact, measurement at the very top would contain undesirable local contact stresses, so we generally measure at least two pile diameters below the top (preferably one circumference).

The Case Method, Wave Mechanics, Theory and Derivations: Soil Resistance Assessment

220

Example Problem 4: Shaft Resistance from Force and Velocity times Impedance Study the following graph and notes.

Force Velocity Shaft Resistance begins to have effect

Toe Reflection begins to arrive at the pile top

2xb/c 2xa/c xa

Ri

a Maximum effect of impact wave is apparent (2L/c after max top velocity)

Ri xb

b

a Determine the apparent shaft resistance force, R i , acting between points A and B. Calculate R i as a percentage of the maximum impact force. b Is R i the total shaft resistance? c Is R i a static resistance force?

The Case Method, Wave Mechanics, Theory and Derivations: Soil Resistance Assessment

221

A.4.3 Resistance from Wave-up While it is instructive to work with F and vZ, it is even more helpful to work with the force in the upward wave, F u . This is because the Wave-up does not include impact waves or other downward wave effects which distract from what we want to see: the effect of soil and pile end on the top measurements. We have seen in Section A.3.2 that the forces in the upward traveling and downward traveling waves (in the following we will just refer to Wave-up and Wave-down to refer to these forces) can be calculated from the measured force and velocity with the following two simple formulas (eqn A.3.9a and eqn A.3.9b). F + Zv  F d = --------------------2 and F – Zv  F u = -------------------2 In other words the force in the Wave-up is one half the difference between F and vZ which in turn is one half the shaft resistance according to what we learned in Section A.4.2. We, therefore, can state that Ri

B–A

= 2  F uB – F uA 

eqn A.4.2

In words: the shaft resistance acting on the pile between points A and B is equal to twice the quantity Wave-up force at time t B minus the Wave-up force at time t A . Figure A.9 shows the transformation of the measurements to the wave forces in the typical PDA display. The graph includes scale (or rather full scale range) information [measured force, F, force in Wave-up, WU, Wave-down, WD, (all forces in kN), measured velocity v (m/s), total display time, TS (ms) and Start of display from the beginning of the record, TB (ms)] and the active sensors A3, A4, F3, F4.

The Case Method, Wave Mechanics, Theory and Derivations: Soil Resistance Assessment

222

F (1500) V (6.98)

vZ

F

WU (1500) WD (1500)

Fd

Fu

Figure A.9: Wave-up and Wave-down calculations for a free-end pile This is a record where the soil resistance is really low; in fact F – vZ and, therefore the shaft resistance is practically zero just before the return of the impact wave. At time 2L  c the velocity sharply increases and the force decreases. At that time the Wave-up curve, being one half of the difference between F and vZ , goes negative, indicating that Wave-up is then a tension force. Before that Wave-up is practically zero, again, indicating a very low shaft resistance.

A.4.4 Calculating the Soil Resistance from Wave-up and Wave-down Let us designate as time t 1 the time when the impact wave passes by the sensor location and as time t 2 = t 1 + 2L  c when the toe reflected impact wave returns to the sensor location. Thus, at time t 1 we have an impact wave of magnitude F d1 traveling downward towards the pile toe. If the resistance force R i acts constant (e.g. velocity is always downward or positive) throughout the time

x  c  t  L  c , then at time

t 2 = t 1 + 2L  c the upward traveling wave contains the effects of :

The Case Method, Wave Mechanics, Theory and Derivations: Soil Resistance Assessment

223

1 the impact wave after reflection at the pile toe where it became an upward traveling tension wave of magnitude – F d1 2 the directly upwards traveling compressive wave from the shaft resistance, magnitude R i  2 3 the initially downward traveling tension resistance wave, now traveling upward in compression after reflection at the bottom, magnitude R i  2 4 the compressive wave caused by the end bearing, magnitude R b Combining all upwards waves at time t 2 we obtain in the order (1) through (4) for the Wave-up at time t 2 : R R F u2 = – F d1 + -----i + -----i + R b 2 2

Upward Travelling Force Wave (WU)

eqn A.4.3a

½Ri-Fd,1+½Ri+Rb

½Ri

L/c Fd,1

2L/c

t

-Fd,1 ½Ri

x

½Ri Rb

L Ri -½Ri

Rb Figure A.10: Upward traveling resistance waves The second and third term on the right hand side of eqn A.4.3a represent the total shaft resistance; adding to it the end bearing makes up for the total resistance R Total . Thus, the combination of all upward traveling waves contains the resistance and the bottom reflected (negative) impact wave of time t 1 . We can, therefore, rewrite eqn A.4.3a as: R Total = F d1 + F u2

eqn A.4.3b

The Case Method, Wave Mechanics, Theory and Derivations: Soil Resistance Assessment

224

eqn A.4.3b can also be expressed in terms of measured forces and velocities at time t 1 and t 2 as:  Ft + Ft  Z  vt – vt  1 2 1 2 R Total = ------------------------- + -------------------------2 2

eqn A.4.4

R Total is the total resistance encountered during a complete passage of the wave between time t 1 and t 2 , i.e., during a time period of 2L  c . There are differences between this total resistance and the ultimate static capacity of the pile and various considerations are necessary to calculate R Static . a Elimination of soil damping. b Proper choice of time t 1 such that R Static is fully mobilized when F and v samples are taken. c Correction for an R Static that decreases between t 1 and t 2 because of early pile rebound or unloading indicated by a negative velocity before 2L  c . d Time dependent soil strength changes (setup or relaxation). Since the dynamic methods give the resistance at the time of testing, it is always recommended to test piles both at the end of driving for an assessment of the strength of the remolded soil and by restriking after a waiting period for the determination of the long-term ultimate capacity. It should not be surprising that the capacity at the end of driving is not equal to the long term pile capacity after an extended waiting period. The waiting period has to be appropriate for the type of soil at the test site. e The pile penetration under the hammer blow. The pile must experience a permanent set (in general we recommend at least 2.5 mm or 0.1”) during the testing for a full mobilization of the soil resistance. If no (or very little) permanent set is achieved then the indicated capacity relates to the mobilized value only which may be less than the pile’s ultimate capacity. This condition is roughly analogous to a static proof test not run to failure because of a limitation of the test setup. The pile set should also not be too large (say more than 12 mm) under the test blow or dynamic effects in the soil could lead to calculated capacities which are greater than the ultimate pile capacity. Considerations (d) and (e) are self-explanatory. The first three considerations will now be investigated in more detail.

The Case Method, Wave Mechanics, Theory and Derivations: Soil Resistance Assessment

225

Example Problem 5: Calculating total Resistance In Example Problem 3 determine the total resistance R Total a from Wave-down and Wave-up and b from the corresponding individual force and velocity values. use the data points identified in the Example Problem 3, i.e., with time 1 at the first major peak.

The Case Method, Wave Mechanics, Theory and Derivations: Soil Resistance Assessment

226

A.4.5 Calculation and consideration of soil damping Damping is associated with the pile velocity and a case can be made that the major soil damping occurs at the pile tip. We can obtain the pile toe velocity from consideration of the arrival and reflection of the impact wave, the R i waves and from the R b wave.From Figure A.10 we can see the various wave components at the pile tip, and convert to velocities using the proportionality for upward and downward waves, to obtain the velocity at the pile tip. i  2F – 2  R - – R b  --- d1 2 v b = ---------------------------------------------------Z

eqn A.4.5

Again the R terms amount to the total resistance and we, therefore obtain under consideration of Eq. 4.3b:  2F d1 – R Total  v b = --------------------------------------Z

eqn A.4.6a

 F d1 – F u2  v b = ----------------------------Z

eqn A.4.6b

or

Knowing the pile toe velocity, the damping component of the total resistance force, R d , may be estimated using a simple linear damping model as R Dynamic = J v v b

eqn A.4.7

The viscous damping factor has units of N/m/s or kips/ft/s. This is a quantity which is rather difficult to work with. For simplification we non-dimensionalize it by division with the pile impedance Z, which has the same unit; we call the new non-dimensional constant the Case damping factor, J c . J J c = ----vZ

eqn A.4.8

Multiplying the toe velocity (Eq. 4.6b) with the Case damping factor leads to the estimated damping resistance: R Dynamic = J c  F d1 – F u2 

eqn A.4.9

The total resistance is the sum of the static and damping resistance. The static resistance can be expected to be the ultimate static resistance, R u , if the pile has been penetrating into the soil permanently under the hammer blow We then can calculate the ultimate capacity of the pile from: R Static = R Total – R Dynamic and therefore

The Case Method, Wave Mechanics, Theory and Derivations: Soil Resistance Assessment

eqn A.4.10

227

R Static =  F d1 + F u2  – J c  F d1 – F u2 

eqn A.4.11a

R Static =  1 – J c F d1 +  1 + J c F u2

eqn A.4.11b

or

The J c damping constant primarily relates to the soil grain size near the pile tip or the major bearing layer and can be back calculated from eqn A.4.11b if measurements have been taken on the pile and its ultimate static capacity, R Static , is known from either a static test run to failure or from CAPWAP. In that case J c is the only unknown in eqn A.4.11a or eqn A.4.11b.

The Case Method, Wave Mechanics, Theory and Derivations: Soil Resistance Assessment

228

Example Problem 6: Calculating Ru for t1at First Peak Velocity a Using the expressions for Wave-down and Wave-up in terms of the measured force and velocity at times t 1 and t 2 , rewrite eqn A.4.11b in terms of the measured force and velocity. b In Example Problems 3 and 5, for times t 1 and t 2 identified, calculate the toe velocity and, assuming a Case Damping factor J c = 0.2 , calculate the damping force and determine the static capacity by subtracting the damping force from the total resistance. c Discuss the R Static result obtained. How sensitive is it to the damping factor J c (for example, calculate R Static also for J c = 0.3 )? Why would the static resistance be so sensitive?

The Case Method, Wave Mechanics, Theory and Derivations: Soil Resistance Assessment

229

A.4.6 Selection of time t1 and the RMX method Static soil resistance is mobilized and increases with pile displacement. To mobilize the ultimate resistance requires that the pile moves under the hammer blow sufficiently enough to activate the resistance both along pile shaft and at the toe. The required maximum displacement can be quite large for large displacement piles. Fortunately, the hammer impact generally produces a relatively large temporary displacement, even if the pile has only a small permanent set. In general, therefore, we expect the ultimate capacity to be mobilized, if the pile set is greater than 2.5 mm or 0.1 inches. That would require that the maximum (temporary) pile set was large enough to cause soil failure. Figure A.11 shows a force, velocity, wave-up and displacement record. Note that the displacement reaches a DMX value (at the sensor location) of 25mm or 1 inch before it rebounds settling at a final permanent set of 2 mm or 0.08 inches.

F (1500) V (6.97)

WU (1500) D (20)

Figure A.11: Example EX-17 shows a pile driven to a hard end bearing layer It is informative to look at the above record more closely. The Wave-up is near zero until at the second solid time line (2L/c after the first major force and velocity peak) where the Wave-up sharply increases, corresponding to an increase in force and a decrease in velocity. This compressive Wave-up is caused by a high toe resistance while shaft resistance in this case is nearly zero. Indeed, this pile was driven to rock, encountering high stress both at the bottom and the top (to be discussed below).

The Case Method, Wave Mechanics, Theory and Derivations: Soil Resistance Assessment

230

Figure A.12 shows six curves. On top are the measured force, F , and velocity, vZ . Below F and vZ we see the Wave-up, F u (WU) and displacement, u (D), curves and below that the total and static resistance curves, R Total (RT) and R Static (RS). R Static has been calculated with a damping factor J c = 0.6 . Also marked on this graph are certain important points: maximum force, FMX, maximum velocity, VMX, maximum displacement, DMX, Wave-up at time t 2 , WU2, static resistance at the first Peak (t 1 ) RP6 and maximum static resistance RX6 (also called RMX for J c = 0.6 ).

F (8000) V (4.25)

FMX, VMX F

vZ WU (8000) D (20)

DMX u

Fu

WU2 RS [JC=0.6] RT (8000)

RX6: 3050kN RTotal RP6: 1510kN

RStatic Figure A.12:

The displacement reaches a maximum of about 15 mm (0.6 inches) shortly after time t 2 ( 2L  c after the first major peak velocity). Not shown in this graph is that the displacement will eventually decrease to a final value DFN = 2.5 mm or 0.1 inches. The resistance curves in the bottom set of curves were calculated by evaluating eqn A.4.11b for each point in time beginning at the first major force and velocity peak. The resulting R Total and R Static values were then plotted at the associated time t 1 . As mentioned above, in the figure below, the static resistance curve was calculated for a damping factor J c = 0.6 . The difference between the static and the dynamic curve is the dynamic resistance, R Dynamic . The static curve increases from an RP6 value of 1510 kN (340 kips) reaching a maximum value RX6 = 3050 kN (690 kips). The maximum Total Resistance is 5200 kN (1180 kips). The highest damping force exists at the time t 1 where the R Total

The Case Method, Wave Mechanics, Theory and Derivations: Soil Resistance Assessment

231

value is 4810 kN (1080 kips) and the damping force is therefore at that time 4810 – 1510 = 3300 kN (1080 - 340 = 740 kips). The damping force decreases while the static resistance increases which is due to the fact that the velocity decreases while the displacement still increases. It is obvious from this example, that the RMX method is more reasonable for this pile of 610 mm or 24 inch width. Three observations are important and support the conclusion that the RP method should not normally be used. It is a method easily understood and evaluated in hand calculations (and therefore used in our example problems), but is not generally used in practical applications. Also please note the following: 1 Damping factors have to be chosen differently for the RPi and the RXi methods. In the present case RP3 (RP with J c = 0.3 ) and RX6 (RX with J c = 0.6 ) would yield approximately the same results. The literature still shows damping factors for the RPi method. In most instances these values would be too low for the RXi method. 2 The sensitivity of the results to an improper damping factor choice is much greater for the RPi than the RXi method. As a demonstration the table below shows the Case Method results for damping factors of 0.5, 0.6 and 0.7. Obviously, the RPi capacities are much more sensitive to damping than RXi values (about 35% vs 7% per each 0.1 change of J c ), because of the higher velocities at time t 1 . 3 The RPi values tend to be too low for large displacement piles because the resistance would not be fully mobilized at t 1 . Table of various Case Method results for the above example case (note the data was taken from PDA Example 1).

Table A.3: Case Method Comparison SI (kN)

English (kips)

Method

Jc = 0.5

Jc = 0.6

Jc = 0.7

Jc = 0.5

Jc = 0.6

Jc = 0.7

RPi

2060

1510

960

460

340

220

RXi

3290

3050

2920

740

690

660

RAU

2630

640

RA2

2850

590

A.4.7 Other methods of interest: RAU, RA2 If the toe velocity (eqn A.4.6a) becomes zero some time after impact, then according to the Case Method definition, the damping resistance R Dynamic is also zero. This implies that any resistance present at this time is static and therefore independent of a damping constant. This solution occurs when v b = 0 .or after substituting for the toe velocity we find that F d1 = F u2 at the time when the bottom velocity is zero. Therefore, calling the associated capacity RAU we can write the following equation: RAU = F d1 + F u2

eqn A.4.12

The Case Method, Wave Mechanics, Theory and Derivations: Soil Resistance Assessment

232

With the condition that F d1 = F d2 . We call this capacity value RAU, because it is automatically static and no damping factor has to be chosen. Graphically it can be seen in Figure A.12 resistance versus time curves when R Total and R Static are for the first time equal. Since this equation assumes resistance to be at the pile toe, it generally will work well if there is little skin friction. One of its applications is also for early, easy driving cases. However, the RAU method may give unrealistically low results in harder driving where large distributed skin friction is present; the result will be conservative, i.e. a lower bound solution. It would be convenient to obtain an estimate of capacity without having to guess a damping factor even in cases of friction piles. For this reason, the RA2 method was formulated which is more generally applicable than RAU. However, both RAU and RA2 methods may underpredict. Since 2011 it is therefore preferred to run the iCAP analyses during data collection and in that way determine the appropriate damping factor during testing. In Figure A.12, the RA2 method gives a capacity prediction of 2850 kN (640 kips) and is, therefore, in reasonably good agreement with the RX6 method while RAU with 2630 kN (590 kips) is somewhat low (indicated at the bottom of the table).

A.4.8 The Unloading Correction Method, RSU The Case Method of capacity prediction “measures” the soil resistance acting at the same time all along the pile. If the energy is sufficient to move the whole pile at the same time downwards when the resistance reaches ultimate, this method leads to satisfactory results. For piles which have a deep embedment relative to the impact induced wave length, the Case Method may underpredict if a substantial amount of the total soil resistance is distributed along the shaft and if, during hard driving, the pile top already rebounds before the resistance is fully activated along the bottom part of the pile. When the pile top velocity becomes negative (e.g. rebounds) before the stress wave returns at time 2L/c, the pile top is moving upward and some of the skin friction near the top begins to unload. For the RPi Method an approximate correction can be calculated in the manner demonstrated in the figure below. Note that this correction is only applicable if the pile top velocity becomes negative prior to t 2 = t 1 + 2L  c . Also, t 1 must be chosen at the first major velocity peak. • Determine the difference time, t u , between the time that the pile top velocity becomes zero and the wave return time t 2 (The time, t u , multiplied by the wave speed, c , and divided by 2 represents the length of pile, L u , over which unloading has likely occurred.) • Measure the resistance, R un , that may have unloaded by taking the Wave-up value at time t 1 + t u . (note that this is only one half of the resistance at t 1 + t u ; the assumption is here that not all resistance has fully unloaded. • Add

R UN to RTL which leads to the corrected RTL U .

• Determine the toe with RTL U taking the place of RTL in eqn A.4.6a.

The Case Method, Wave Mechanics, Theory and Derivations: Soil Resistance Assessment

233

• Apply the proper damping factor (to be verified by CAPWAP).

F (5000) V (2.64)

2L/c tu

time of zero velocity WU (5000) D (10)

tu 'Run RS [JC=0.3] RT (5000)

Figure A.13: Record illustrates a pile with ‘early unloading’ In Figure A.13 (PDA Example data Ex-21c), the bottom graph shows again the R Total and R Static curves. Both decrease at a rather steep slope immediately after time t 1 . This is typical for unloading cases where the energy provided by the hammer is just not sufficient to maintain a downward pile motion for a sufficiently long time for complete, simultaneous resistance activation. This immediate decrease of the resistance curves also means that RPi and RXi are identical. In this example, RTL is 4480 kN (1010 kips) and RTL U is 5240 kN (1180 kips) which means that the unloading correction, R UN , was 760 kN (170 kips). Assuming a damping factor J c = 0.3 (relatively low damping factors are used for the RPi Method) we obtain RP3 = 3550 kN (800 kips) and RU3 = 4540 kN (1020 kips). Note that, compared to RTL, the increased RTL u causes the toe velocity and therefore the damping resistance to decrease.

A.4.9 Total and static shaft resistance (skin friction) We have seen in Section A.4.2 and Section A.4.3 that the upwards traveling shaft resistance waves create a difference between F and vZ or an increasing Wave-up before time 2L  c . The question is now, how we can get a closed form estimate of both the total shaft resistance and the total static shaft resistance acting on the pile. Consider the

The Case Method, Wave Mechanics, Theory and Derivations: Soil Resistance Assessment

234

figure below. It shows F and vZ on top and F d and F u below. Indicated are also times t 1 (first major velocity peak and t 2 = t 1 + 2L  c . A black heavy horizontal bar between the top and bottom graph, beginning at t 1 and ending at t 2 is a schematic of the pile with its top at t 1 and its toe at t 2 .

F (1200) V (9.30)

A

WU (1200) D (1.00)

B

C

tcl tcl ½SFT

t1

t2

Figure A.14: Total shaft resistance is calculated through extrapolation The A-time line indicates where the Wave-up curve is still zero. Assuming that any shaft resistance acting at the top (actually at the sensor location) would be activated at time t 1 , we can say that from the top to the point A along the pile, no (or not much) shaft resistance acts. At Point B a small amount of shaft resistance has its effect and from this point on the Wave-up curve increases somewhat linearly to point C. The difference F uC – F uB is ½ of the total (static plus damping) shaft resistance acting between point B and C. The problem is now, that we do not know the shaft resistance acting between C and the peak pile toe reflection, because of the superimposed reflected impact wave which creates a valley in the Wave-up curve. We solve this problem by going back from point C a distance t c and extrapolating linearly to t 2 . The point thus determined defines ½ SFT, providing an estimate of one half of the total (damping plus static) shaft resistance.

The Case Method, Wave Mechanics, Theory and Derivations: Soil Resistance Assessment

235

The next question is how we can figure what the static shaft resistance is. We solve this problem in an approximate manner by reducing SFT proportionally to the RMX resistance. Thus, the reduced shaft resistance is calculated as RXJ SFR = SFJ = SFT  -----------  RX0

eqn A.4.13

and the associated end bearing is EBJ = RXJ – SFJ

eqn A.4.14

(e.g., for Jc=0.5: SF5 = SFT(RX5/RX0) and EB5 = RX5 – SF5). Note that in the above derivation of end bearing it is assumed that the shaft resistance will be activated at time t 1 , however the end bearing (and therefore the maximum capacity value) will take more displacement and thus a longer time for complete activation. For that reason, the sum EBR + SFR does in general not equal the RPJ result. Note also that this method can only yield a reasonable static shaft resistance estimate for uniform piles without a major unloading problem which would be apparent by the Wave-up curve becoming negative before 2L  c .

The Case Method, Wave Mechanics, Theory and Derivations: Soil Resistance Assessment

236

Example Problem 7: Estimates of Shaft Resistance and End Bearing

Force Velocity

WaveUp WaveDown

t1

t2

SI

English

Pile Size

450 mm

18 in

Specific Weight 

23.6 kN/m3

150 lb/ft3

Length Below Sensors (LE)

23.5 m

77 ft

Time 1

22.7 s

22.7 s

Time 2 (t1+2L/c)

35.3 s

35.3 s

Force at t1 (FT1)

2790 kN

630 kips

Force at t2 (FT2)

650 kN

150 kips

velocity at t2 (VT2)

-0.14 m/s

-0.45 ft/s

With the measurements and information shown above taken on a uniform square prestressed concrete pile, calculate: a The cross-sectional area (A): b The wavespeed of the pile (c): c The elastic modulus (E): d The pile impedance (Z): e The velocity at time 1 (VT1) f

The force Wave-down at time 1 (WD1):

g The force Wave-up at time 2 (WU2): h The total resistance at time 1 (RTL):

The Case Method, Wave Mechanics, Theory and Derivations: Soil Resistance Assessment

237

i

The Static resistance at time 1(assume J c = 0.5) (RP5)

j

The total shaft resistance at time 1 (SFT):

k The static shaft resistance at time 1(assume J c = 0.5) (SF5): l

The estimated end bearing at time 1(assume J c = 0.5) (EB5):

m Would the RAU method be appropriate? n Would this be a case benefiting from the unloading correction? Note: Since the maximum resistance does not occur at t 1 , the EBR value which relates to the RMX method will be different from your estimate for t 1

The Case Method, Wave Mechanics, Theory and Derivations: Soil Resistance Assessment

238

A.4.10 Energy Approach Capacities QUS, QUT This method of capacity calculation from F and v measurements is not an original Case Method approach, but has been described by others, for example Paikowsky. The Case Method looks at individual force and velocity values and determines resistance from a force equilibrium point of view. The Energy Approach is based on the conservation of energy as it was done for years in dynamic formulas; in contrast, however, this Energy Approach uses measured values for energy and energy losses (pile rebound) instead of estimates.

Resistance Ru

Displacement

0

q

1

umax ufin

2

Figure A.15: The energy method calculates a resistance from the measured energy and blow count Figure A.15 shows a simplified plot of elasto-plastic resistance, R , vs. pile displacement, u . Beginning at point “0” this simple plot suggests that the resistance increases linearly with displacement until point “1” where the displacement reaches the quake value and the ultimate resistance, R u . Beyond that point the resistance does not increase while the displacement increases further to point “2” where the maximum displacement is reached. Beyond that point 3, the pile rebounds with the resistance decreasing linearly at a slope as defined by the quake. At point “2” where the maximum displacement is reached, the soil resistance has done a maximum amount of work, after that energy is given back to the hammer. This amount of energy is equivalent to the area under the force-displacement curve or E max = R u  u max – q---  2

eqn A.4.15a

 u max – u fin  E max = R u  u max – -------------------------------  2

eqn A.4.15b

And substituting for q

The Case Method, Wave Mechanics, Theory and Derivations: Soil Resistance Assessment

239

or solving for R u 2E max R u = ------------------------------- u max + u fin 

eqn A.4.16

As shown in Section A.7, the maximum energy transferred to the pile, called EMX, can be calculated from force and velocity records. Furthermore, the measured maximum pile top displacement is DMX. So, if we knew the u fin value we could readily evaluate Eq. 4.16. PDA-W solves this problem by accepting a set per blow value, SET, as an input. Alternatively it can use the final displacement, DFN, from double integration of the measured acceleration. The corresponding results calculated are then 2EMX QUS = ----------------------------------- DMX + SET  or 2EMX QUT = ------------------------------------- DMX + DFN  Note that when the drive log is used, corrections to the displacement curve are applied such that the set is final displacement, DFN, is equated to the measured set per blow and thus QUS and QUT become essentially the same value. The program also calculates an RQJ value which is either QUT or RXJ, whichever is greater. The problem with this approach is that either QUS or QUT are really dynamic resistance values (not static) and that they therefore tend to be non-conservative. Also using pile top quantities is not strictly correct if we consider an energy balance for the soil. And finally, the soil does not offer a total concentrated resistance force which is elasto-plastic, for example, the real damping forces are ignored in this computation. Considering the resistance is distributed along the pile and considering it consisting of a static and a damping component is definitely a more realistic approach. A thorough study has not been made, but it appears that for end-of drive situations, the result is about 40% higher than CAPWAP and for restrikes it is, on the average, about twice as high as CAPWAP. Thus the energy result should clearly be reduced. However, on a caseby-case basis the percentage reduction may be quite variable and thus unreliable to use one factor for every case. The reader is strongly encouraged to read the following reference: (Rausche, et.al, 2004)

The Case Method, Wave Mechanics, Theory and Derivations: Soil Resistance Assessment

240

A.5 Stress Calculations Pile damage can be the result of poor hammer alignment (high local contact or bending stresses), obstructions in the ground which cause the pile to be bent or subjected to a non-uniform toe resistance (high local contact or bending stresses). The most common cause for pile damage is, however, an overstressing due to high hammer impact forces which can generate excessive compression stresses at the pile top or bottom (high end bearing) or also high tension stresses somewhere along the length of the piles. Concrete piles are particularly vulnerable to excessive tension stresses.

A.5.1 Pile top (sensor location) stresses The PDA measurements of strain on two or even four sides of a pile, multiplied by the elastic modulus, yield stresses at the measurement location. The single highest stress at a transducer location is called CSI by the PDA. If the transducer happens to be in the plane of highest bending then CSI is a good indicator of bending stresses at the sensor cross section. It is calculated simply as: CSI = EM  max   i  

eqn A.5.1

where max   i  is the highest strain measured by anyone of the two or four strain transducers. Of course, other cross sections may have different bending stresses. Static bending, e.g., due to an inappropriate or other methods of guiding the pile, cannot be detected by the PDA. Thus, while CSI may be helpful to judge the hammer-pile alignment, particularly when 4 strain sensors are used, the PDA cannot provide a thorough bending assessment neither at the top nor anywhere else along the pile. Important is also the average stress at the sensor location, CSX, because it is what is normally compared with the allowable driving stresses. CSX can be calculated from the average of the strain readings as follows:  1 + 2  CSX =  ---------------------- EM   2

eqn A.5.2a

for two strain transducer applications or  1 + 2 + 3 + 4  CSX =  ---------------------------------------------- EM   4

eqn A.5.2b

for four strain transducers. Also, please note that the stresses above the sensor location cannot be easily calculated from measurements.

A.5.2 Pile toe stresses Suppose a pile is driven theoretically possible that impact force (or twice the not even a hard rock is

to a very hard layer. As we have seen, in that case it is the pile will experience a pile bottom force which is twice the force in the Wave-down at the initial impact). In general, since absolutely rigid, such high end bearing force cannot fully

The Case Method, Wave Mechanics, Theory and Derivations: Stress Calculations

241

materialize, however, it is definitely possible that the pile toe stresses exceed those at the top; amplification factors of 1.5 or more have been observed. The total toe resistance force is calculated by the PDA considering the maximum total (static plus damping) resistance minus the effect of the shaft resistance. This force is called CFB; approximately it is equal to CFB = RX0 – c b SFT

eqn A.5.3a

where c b is an adjustment factor which since 2011 is chosen by the PDA as 0.5 for conservatism and to match theory. The corresponding stress is CSB = CFB -----------AR

F (1500) V (6.97)

eqn A.5.3b

CSX: 233 MPa (33.8 ksi) CS1: 169 MPa (24.5 ksi)

CSB: 264 MPa (38.2 ksi) F1 (1500) F2 (1500)

CSI: 245 MPa (35.5 ksi)

Figure A.16: Stresses at the pile toe become a concern in hard driving scenarios, especially with little shaft resistance. The Figure A.5.3 shows an F and vZ record for a pile with little shaft resistance and high end bearing (note the strong increase of force at time 2L  c ). At the top the maximum stress, averaged over the cross section (233 MPa or 33.8 ksi) happens not at impact, but when the wave returns from the pile toe. Evaluating this record for pile toe stresses according to Figure A.5.3a&b yields a pile to stress of 264 MPa (38.2 ksi) or about 56%

The Case Method, Wave Mechanics, Theory and Derivations: Stress Calculations

242

more than the stress at impact (time t 1 ). The individual strain records also indicated bending of 5% above the average stress at the peak stress level; at impact, where the stresses were lower, the bending effect was more pronounced.

A.5.3 Pile tension stresses caused by Wave-up For concrete piles it is highly desirable to know the tension stresses, but at the sensor location, measured tension stresses are usually not very high, because of the reflection taking place at the pile top where tension has to be zero. We therefore have to calculate the tension stresses at points below the location of the sensors. We can do this by remembering that the force at a point is the sum of the forces in Wave-down plus the force in the Wave-up. In easy driving we normally see a tension wave traveling upwards arriving at the pile top around the time 2L  c . In hard driving we sometimes see a downward traveling tension wave after 2L  c . For the easy driving case, consider Figure A.17. It shows both Wave-down (purple) and Wave-up (green). Wave-up becomes strongly negative at time 2L  c . Thus a tension wave travels up from the pile bottom due to the reflection of the impact wave. Let us call t = 0 as the time at which the maximum impact force is apparent. As shown in the L-t plot underneath the record, we can calculate the force at any level x as the sum of the downward wave emanating from the top at time y = 2  L – x   c after the time of impact plus the upward wave arriving at the top at time t=2L/c. If we chose t = 0 such that the upwards traveling wave, F u2 , represents the highest tension and if we choose x such that F d3 is the lowest downward traveling compression during the first 2L  c , then F x will be the highest tension force in the pile during the first 2L  c .

The Case Method, Wave Mechanics, Theory and Derivations: Stress Calculations

243

Wave Up Wave Down

L/c

2L/c

t

L

Figure A.17: From time L/c the upward tension wave encounters all points on the downward traveling force wave. The Figure A.18 shows how we can expand on this concept to determine the tension stress envelope caused by the recorded event. (The PDA calculates the tension envelope in the same way.)

The Case Method, Wave Mechanics, Theory and Derivations: Stress Calculations

244

F (2000) V (9.2)

WU (2000) WD (2000)

Pile Toe

Pile Head Tension Envelope

min Fu min Fu

Figure A.18: The maximum traveling tension force in the Wave-up curve will encounter all points of the Wave-down curve from time L/c. • Determine the point of minimum Wave-up and determine minFu . • At the time of minimum Wave-up we draw a heavy bar backward in time for 2L  c and call the beginning “the pile top” and the end point “the pile toe”. The reason is that a downward compression wave observed just before the time of minimum Wave-up will have a tension reducing effect very near the pile top. • In the Wave-down plot, draw a horizontal line at a distance of minFu above the zero line from “pile top” to “pile toe” • Where the Wave-down is less than minF u , the difference between the horizontal line and the Wave-down curve is the net tension force along the pile. • Determine the point of minimum Wave-down, minFd , which happens to be the point where the maximum net tension occurs. You can calculate the distance below the pile top where the tension is maximum from the relative distance of the point of minFd from the point of minFu . Again, the maximum net computed tension (CTN) occurs when the downward compression force is a minimum (time t 3 ) and can be found mathematically by CTN = minF u + minF d The associated stress is

The Case Method, Wave Mechanics, Theory and Derivations: Stress Calculations

eqn A.5.4a

245

CSN = CTN -----------AR

eqn A.5.4b

Obviously, this method is only correct for uniform, undamaged piles.

The Case Method, Wave Mechanics, Theory and Derivations: Stress Calculations

246

Example Problem 8: Tension Stress Calculation from Wave-up

100%

WaveUp WaveDown

t1

t2

In the above Wave-down and Wave-up record, determine the following values: a Minimum (maximum tension) Wave-up as a percentage of maximum Wave-down; b Minimum Wave-down as a percentage of maximum Wave-down; c Relative distance from the pile top where maximum net tension occurs.

The Case Method, Wave Mechanics, Theory and Derivations: Stress Calculations

247

A.5.4 Pile tension stresses caused by Wave-down At the end of Section A.3.3 we have considered a situation of a rigid support at the bottom of a pile and we have seen that this situation causes a compressive Wave-up reflection at the pile toe. This upward traveling wave will have an upward directed particle velocity. When this wave arrives at the pile top it can encounter either a downward moving ram which causes a compressive downward wave or, particularly if the ram is very light and has lost its momentum, something close to a free pile top which then causes a downward tension reflection. In general, when driving is very hard (which means the hammer does not have enough momentum to keep the pile in compression), damaging tension waves can happen in the hard driving case. The F , vZ records in such cases have a large negative velocity at a time when the force is relatively low. Obviously, with F d =  F + vZ   2 , the negative velocity will make the Wave-down a tension wave.

F (2000) V (9.2)

Pile Head

WU (2000) WD (2000)

minimum upward traveling compression wave 2L/c Pile Toe 2L/c maximum downward traveling tension wave

Figure A.19: While no tensile stresses occur in the first 2L/c, tension in the downward traveling wave after 2L/c cause net tensile stresses near the pile toe. Figure A.19 shows the example of a large negative velocity not offset by a positive force and, therefore, a negative Wave-up curve. The PDA determines the minimum Wavedown value in tension and then searches for a trailing minimum compressive Wave-up; adding it to the maximum tensile Wave-down yields the maximum net tension force, CTX. The associated stress TSX is calculated by division with the cross sectional area. Again this only works for uniform piles. Note, however, that the PDA outputs TSX as always the greater of the tension from upward or downward waves.

The Case Method, Wave Mechanics, Theory and Derivations: Stress Calculations

248

A.6 Damage Detection For a uniform pile, an upward traveling tension wave should be observed only after reflection from the pile tip and should therefore come at time 2L  c . If an upward tension wave is observed prior to 2L  c , it must be due to a reduction in pile impedance, i.e., either a reduced cross sectional area or a reduced elastic modulus or a reduced mass density all of which should be considered either a damage or defect in a uniform pile.

Wave Up Wave Down

L/c Fd1 x

2L/c

Fd1

Fd1

t

Fd1

Z1

Fu1

Fu1

Fu1

Fu1

A B

L

Fd2

Fd2

Fd2

Fd2

Z2

Figure A.20: Consider the figure below showing on the left hand side a schematic pile which has impedance Z 1 on top and which has a reduced impedance, Z 2 , below x . As shown on the right hand side of the figure, because of the impedance reduction the impact wave F d1 will be partially reflected at x sending a reflection wave F u1 upwards which arrives at the top at time 2x  c . It will be apparent at the pile top and can then be evaluated. Additionally, the initial input wave, F d2 will continue to travel to the pile toe but at a reduced magnitude due to the section reduction to satisfy equilibrium. Consider the wave forces acting at section A and B, i.e. just above and below the impedance reduction; because they have to be in equilibrium we have: F d1 + F u1 = F d2

eqn A.6.1

Similarly, the velocities in these waves have to be equal on both sides or else we would not have continuity (the pile would separate):

The Case Method, Wave Mechanics, Theory and Derivations: Damage Detection

249

v d1 + v u1 = v d2

eqn A.6.2a

Considering proportionality we can replace the velocities in eqn A.6.2a by the corresponding wave forces: F d2 F d1 F u1 --------- – --------- = --------Z1 Z1 Z2

eqn A.6.2b

We are now defining the integrity factor Z  = -----2Z1

eqn A.6.3

which is 1 for Z 2 = Z 1 (undamaged) and zero for a completed damaged pile. Now after multiplication with Z 2 , eqn A.6.2b can be expressed as F d2 =   F d1 – F u1 

eqn A.6.3a

and combining eqn A.6.1 and eqn A.6.3a to eliminate F d2 we find that  F d1 + F u1   = ---------------------------- F d1 – F u1 

eqn A.6.4

Let us assume that F u1 is an upward traveling wave which is tensile and 30% of the  1 – 0.3  0.7 magnitude of the impact wave. In that case  = ---------------------- = ------- = 0.54 . Thus in that case  1 + 0.3  1.3 Z 2 would be slightly more than ½ of the pile top impedance. Reality is actually more complicated because the wave F d1 , by the time it has reached the point A has already possibly lost some intensity due to the resistance, R x , acting over the distance x above the section reduction. For that reason then PDA-S program uses a modified equation which considers the effect of soil resistance:  F d1 – 1.5R x + F u1   = ------------------------------------------------- F d1 – 0.5R x – F u1 

eqn A.6.5

The eqn A.6.5 gives reasonable and conservative results in most cases. Several additional considerations can be given, among them: • Theoretically an extrapolation of the shaft resistance to the point of highest tensile wave ( F d1 ) should be made (particularly, where damage is gradually worsening with depth). • Soil damping reduces the downward wave more than indicated by the R x value, because of its temporary (velocity dependent) nature. • Structural/pile material damping reduces impact and reflection waves, particularly in concrete piles with microcracks.

The Case Method, Wave Mechanics, Theory and Derivations: Damage Detection

250

• Soil resistance at the bottom of the damage (in extreme cases like an end bearing) reduces the reflection. • Compressive wave reflections from an impedance increase may be observed at the end of the damage (if the damaged portion is shorter than the wave length). • Resistance from connecting steel strands or other damaged pile sections at the bottom of the damage may affect the calculated magnitude and location of the damage. While these and other effects add resistance or resistance like effects and therefore reduce the apparent damage reflection, the PDA generally calculates a ß-value that is low or conservative where high shaft resistance exists above the damage. In order to provide a guideline for uniform damage assessment, the following table shows a classification scale which has been proposed (Rausche et al., 1979), a paper which is also the source of eqn A.6.5. Additional considerations for damage at the toe are discussed in detail under this paper (Likins and Rausche, 2014) Damage Assessment based on  -values

Table A.4: Beta Recommendations ß

Suggested Pile Condition

1.0

Uniform

0.8 - 1.0

Slightly Damaged

0.6 - 0.8

Damaged

< 0.6

Broken

Of course, such damage assessment cannot be directly applied to a crack, broken weld, bent steel pipe or many other damage situations which do not conform to the basic assumption in the derivation:  is a measure of the remaining impedance or crosssection. However, if the impedance ratio becomes 0.6 or less, it is unlikely that the pile can be fully functional. Also, a distinct pile toe reflections is then rarely observed. In all cases it is suggested to try modeling the supposedly damaged pile with CAPWAP to confirm the findings by the simpler  -method. Finally a word should be said about the determination of the location of the damage. The PDA calculates the time 2x  c from the onset of Wave-down at impact to the beginning of the apparent tensile reflection, F u1 . This time multiplied by ½ of the wave speed is the best estimate of the beginning of the damage. Obviously, an incorrect wave speed will produce an incorrect length x . In fact, if the wave speed had been assumed too low, the PDA might indicate damage just above the pile toe. If and only if damage can be definitely ruled out, then the wave speed can be determined by increasing it until the PDA’s damage indication disappears.

The Case Method, Wave Mechanics, Theory and Derivations: Damage Detection

251

F (2600) V (2.12)

Onset of Fd1 L F x=0.75L

vZ

WU (2600) WD (2600)

Fd1=100% Fu

Fu1=30%

½Rx=4.4%

Fd

Figure A.21: Figure A.21 shows a record was taken on a 356 mm (14 inch) square prestressed concrete pile. Before damage occurred, given the length of LE=19.5 m (63 ft) below gages and a clear toe reflection, the wave speed was determined to be WS=4,040 m/s (13,250 ft/s). The record’s force scale was adjusted so that F d1 = 100% (actually 2600 kN, but we can do the calculation non-dimensionally). Clearly the Wave-up record shows a tensile reflection beginning at a time which is 75% of 2L  c . Thus damage is apparent at a depth of 14.5 m (47.6 ft). The Wave-up value just before the tensile reflection is 4.4% of full scale ( R x is therefore 8.8%). The tensile reflection F u1 is -30%. Introducing these values in eqn A.6.5 leads to: 100 – 1.5  8.8  +  – 30   = 0.45  = ------------------------------------------------------------- 100 – 4.4 –  – 30   indicating a broken pile. Note that ignoring the relatively minor resistance effect would have yielded a  of 0.54 (eqn A.6.4).

The Case Method, Wave Mechanics, Theory and Derivations: Damage Detection

252

Example Problem 9: Damage Assessment

Force Velocity

Wave Up Wave Down

For the above record of a 35.7 m (117 ft) long (below sensors) steel pile, calculate the depth of damage and its severity. What could be the reason for such a clear damage reflection in a steel pile?

The Case Method, Wave Mechanics, Theory and Derivations: Damage Detection

253

A.7 Hammer Performance The energy transferred to the pile, E t  t  , can be found from the work done on the pile Et  t  =

 F  t  du

=

 F  t v  t  dt

eqn A.7.1

which we can obtain if we integrate the product of force ‘F’ and velocity ‘v’ over time. The maximum value is the maximum transferred energy EMX. EMX = max  E t  t  

eqn A.7.2

It is important to realize that only this transferred energy, EMX, is capable of actually doing work, rather than the hammers rated energy, Er (called ER by the PDA). The transferred energy only allows the hammer’s performance to be judged, but only in a statistical manner, by its energy transfer ratio (or transfer efficiency,  t ) which is defined as  t = ETR = EMX ------------ER

eqn A.7.3

Additional definitions of interest are the impact velocity which for a given stroke ‘h’ is vi =

2gh

eqn A.7.4

with g being the gravitational acceleration. Given the ram mass, m r , the kinetic energy is 2

mr vi E k = ----------2

eqn A.7.5

If we measure the impact velocity of the ram then we can calculate the actual kinetic energy and from it the actual hammer efficiency,  H , as the ratio of the measured kinetic energy divided by the rated energy. Note: the hammer efficiency expresses losses in the hammer, occurring prior to impact. The transfer ratio expresses energy losses occurring in hammer, driving system (cushions and helmet) and at the pile top surface. While Radar (PDI’s Hammer Performance Analyzer, HPA) or other device can measure the effective impact velocity in most situations, it is also possible under certain circumstances (and it may be simpler) to calculate it from the F and v records. The evaluation of the records would require applying the principles of impulse and conservation of linear momentum. The impulse can be calculated from either the measured force as MFO =

 F  t  dt

eqn A.7.6

The integral should be evaluated from time 0 (when the force at the pile top begins to increase) until the time when the ram velocity again becomes zero. Since we don’t know

The Case Method, Wave Mechanics, Theory and Derivations: Hammer Performance

254

that time we have to assume that the ram velocity becomes zero together with the pile top velocity. This assumption can be verified by wave equation analysis and precludes the application of the impulse-momentum relationship for concrete piles with soft cushioning. Also, since diesel hammers have energy added during the impulse evaluation period, this hammer type does not lend it to this method either. A force impulse can also be calculated from the Wave-down curve: MWO =

 Fd  t  dt

eqn A.7.7

This integration should go from time 0 until the time when the Wave-down becomes zero. Equating the impulse to the momentum of the ram, which is equal to ram mass times impact velocity ( m R v i ) we can calculate the ram impact velocity as either v i = MFO -------------mR

eqn A.7.8a

MWO v i = --------------mR

eqn A.7.8b

or

This ram impact velocity can be used to obtain the kinetic energy 2

mR v i E k = -----------2

eqn A.7.9

which can be compared with the rated energy, E R , to obtain the hammer efficiency E  H = ------kER

??? ?.7.10

Also, comparing the kinetic energy with the maximum transferred energy EMX will demonstrate the effectiveness of the rest of the driving systems. In summary, two energy ratios are important and must be distinguished: E The hammer efficiency:  H = ------kER E EMX The transfer ratio (efficiency):  t = ETR = ------t- = ------------ER ER For open end diesel hammers, it is also important to check the hammer stroke. Given the time between hammer blows, T, and assuming that the ram travels freely (no friction or other losses of energy) the time for the ram fall (or ram rise) is equal to T/2. If the velocity increases linearly due to the gravitational acceleration, g , then

The Case Method, Wave Mechanics, Theory and Derivations: Hammer Performance

255

T v i = g  ---  2

eqn A.7.11a

and combining with eqn A.7.4 to cancel v i , we obtain T 2gh = g  --- 2

eqn A.7.11b

g 2 h =  --- T  8

eqn A.7.11c

or

Since a diesel hammer loses some of its ram velocity due to the precompression of the gases in the combustion chamber, based on field tests and wave equation simulations we found that h would be more correctly calculated after subtracting a loss term, h L = 0.1m or 0.3ft . Thus the Saximeter formula is g 2 h =  --- T – h L 8

eqn A.7.11d

or in terms of blows per minute s 2  60 ---------- g min h =  ---  ---------------- – h L  8  BPM   

eqn A.7.11e

For example, if the time between two hammer blows is 1.5 s, then h is 2.66 m (8.75 ft).

The Case Method, Wave Mechanics, Theory and Derivations: Hammer Performance

256

Example Problem 10: Hammer Performance a Calculate the stroke of a diesel hammer if the hammer runs at 38 blows/minute. Consider a hammer with a 44.5 kN (10 kip) ram with a rated stroke of 1.0 m (3.3 ft) and an observed impulse (MFO) of 17.8 kN-s (4.00 k-sec) and EMX of 24.4kJ (18.0 k-ft). Calculate the hammer’s: b Rated energy, c Rated impact velocity, d Actual impact velocity, e Kinetic energy, f

Hammer efficiency,

g Transfer ratio (efficiency)?

The Case Method, Wave Mechanics, Theory and Derivations: Hammer Performance

257

A.8 Results of Example Problems Answer to Example Problem 1: Wave Speed, c Calculate the wave speed for a concrete with a dynamic elastic modulus of 35,000 MPa (5,000 ksi) and unit weight = 24 kN/m 3 (150 lb/ft 3 ).

c =

c =

E --- = 

E --- = 

Eg ----------------- = 

Eg ----------------- = 

2

35000MPa  1000MPa/KPa   9.81m  s  ----------------------------------------------------------------------------------------------------- = 3782m  s 3 24kN  m

2

2

2

 5000ksi   1000kip/ft   144in  ft   32.2ft  s  ----------------------------------------------------------------------------------------------------------------------- = 12432ft/s 150pcf

Repeat the calculation for b timber (E = 12,000 MPa or 1,800 ksi and = 8 kN/m 3 or 50 lb/ft 3 )

c =

c =

E --- = 

E --- = 

Eg ----------------- = 

Eg ----------------- = 

2

12000MPa  1000MPa/KPa   9.81m  s  ----------------------------------------------------------------------------------------------------- = 3836m  s 3 8kN  m

2

2

2

 1800ksi   1000kip/ft   144in  ft   32.2ft  s  ----------------------------------------------------------------------------------------------------------------------- = 12920ft/s 50pcf

c and steel (E = 210,000 MPa or 30,000 ksi and = 77 kN/m 3 or 492 lb/ft 3 ).

c =

E --- = 

Eg  ----------------- = 

2

210000MPa  1000MPa/KPa   9.81m  s  --------------------------------------------------------------------------------------------------------= 5172m  s 3 77kN  m

The Case Method, Wave Mechanics, Theory and Derivations: Results of Example Problems

258

c =

E --- = 

E g  ----------------- = 

2

2

2

 30000ksi   1000kip/ft   144in  ft   32.2ft  s  -------------------------------------------------------------------------------------------------------------------------- = 16833ft/s 492pcf

The Case Method, Wave Mechanics, Theory and Derivations: Results of Example Problems

259

Answer to Example Problem 2: Impedance, Z Compute the impedance of a pile for a 27.5 cm (11 inch) square concrete pile of 30 m (100 ft) length using concrete properties in Example Problem 1. Do the computations for all three equations 2.2 a, b and c. 2

A =  27.5cm  = 756.25cm 2

A =  11in  = 121in

2

2

2

2

2

 35000MPa   1000kN  MN   756.25cm   1m  10000cm  Z = EA -------- = --------------------------------------------------------------------------------------------------------------------------------------------------------- = 700kN   m  s  c 3782m  s 2

 5000ksi   121in  Z = EA -------- = ----------------------------------------------- = 48.7kip   ft  s  c 12432ft/sec

3

2 2 2 24kN  m Z = cA = -------------------------  3782m  s   756.25cm   1m  10000cm  = 700kN   m  s  9.81m  s 2 2 2 150pcf Z = cA = --------------------2-  12432ft/sec   121in   1ft  144in  = 48.7kip   ft  s  32.2ft/s

 24kN  m 3 2 2 2  ------------------------2-  756.25cm   1m  10000cm   30m   3782m  s   9.81m  s  Z = Mc -------- = ------------------------------------------------------------------------------------------------------------------------------------------------------------------ = 700kN   m  s  30m L lb 150pcf   2 2 2  -------------------- 1000 --------  121in   1ft  144in   100ft   12432ft/sec  2   kip 32.2ft/s Z = Mc -------- = ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------- = 48.7kip   ft  s  L 100ft for the two remaining materials SI Material

E

Wood

12,000

Steel

210,000

English c

Z

E

8

3,836

237

1,800

77

5,172

3070

30,000

c

Z

50

12,934

16.8

492

16,833

215.6

The Case Method, Wave Mechanics, Theory and Derivations: Results of Example Problems

260

Answer to Example Problem 3: Wave-down and Wave-up Values Force Velocity

t1

t2

Given force and velocity at the pile top of a square prestressed, precast concrete pile (see figure above), what is the magnitude of both the downward and upward traveling wave forces at both times, t 1 and t 2 given the following values:

SI

English

Elastic Modulus

42,000 MPa

6000 ksi

Square Pile Width

610 mm

24 in

Specific Weight

24 kN/m3

150 pcf

Force at t1

4000 kN

900 kips

Force at t2

-200 kN

-50 kips

Velocity at t1

1.0 m/s

3.3 ft/s

Velocity at t2

1.0 m/s

3.3 ft/s

(Note, force and velocity values were rounded and cannot be exactly scaled in the figure) First we need to calculate the wavespeed, c, of the pile: c =

c =

E --- = 

E --- = 

42000MPa  1000kPa/MPa  m --------------------------------------------------------------------- = 4143 ---3 2 s   24kN/m    9.81m  s  

2

2

6000ksi  1000lb/kip   144in  ft  ft ------------------------------------------------------------------------------------- = 13619 --2 s  150pcf  32.2ft/s 

The Case Method, Wave Mechanics, Theory and Derivations: Results of Example Problems

261

Then we can calculate the pile impedance, Z: 2

m  42000MPa   1000kPa/MPa   0.61m  Z = EA -------- = --------------------------------------------------------------------------------------------------- = 3772kN  ---s c m 4143 ---s 2

ft  6000ksi   24in  Z = EA -------- = -------------------------------------------- = 253.7kip  --s c ft 13619 --s We can now calculate the Wave-Down and Wave-Up terms:

F d1

· m  4000kN  +  1.0m/s   3772kN  ---- Ft + vt Z  s 1 1 = ------------------------ = ---------------------------------------------------------------------------------------- = 3886kN 2 2

F d1

· ft  900kip  +  3.3ft/s   253.7kip  --- Ft + vt Z  s 1 1 = ----------------------- = --------------------------------------------------------------------------------------- = 868.6kip 2 2

F d2

· m  – 200 kN  +  1.0m/s   3772kN  ---- Ft + vt Z s 2 2 = ----------------------- = ---------------------------------------------------------------------------------------- = 1786kN 2 2

F d2

· ft  – 50 kip  +  3.3ft/s   253.7kip  --- Ft + vt Z s 2 2 = ----------------------- = --------------------------------------------------------------------------------------- = 393.6kip 2 2

F u1

m  4000kN  –  1.0m/s   3772kN  ---- Ft – vt Z  s 1 1 = ---------------------- = ---------------------------------------------------------------------------------------- = 114kN 2 2

F u1

· ft  900kip  –  3.3ft/s   253.7kip  --- Ft – vt Z  s 1 1 = ----------------------- = -------------------------------------------------------------------------------------- = 31.4kip 2 2

F u2

m  – 200kN  –  1.0m/s   3772kN  ---- Ft – vt Z s 2 2 = ----------------------- = ---------------------------------------------------------------------------------------- = – 1986k N 2 2

F u2

· ft  – 50kN  –  3.3ft/s   253.7kip  --- Ft – vt Z s 2 2 = ----------------------- = -------------------------------------------------------------------------------------- = – 443.6kip 2 2

The Case Method, Wave Mechanics, Theory and Derivations: Results of Example Problems

262

Answer to Example Problem 4: Shaft Resistance from Force and Velocity times Impedance tudy the following graph and notes.

Force Velocity Shaft Resistance begins to have effect

Toe Reflection begins to arrive at the pile top

2xb/c 2xa/c xa

Ri

a Maximum effect of impact wave is apparent (2L/c after max top velocity)

Ri xb

b

a Determine the apparent shaft resistance force, R i , acting between points A and B. Calculate R i as a percentage of the maximum impact force. The resistance force between point A and B amounts to approximately 47% of the impact force. b Is R i the total shaft resistance? There could be additional resistance on the shaft below point B, but the magnitude is not obvious from the record. There is little or no shaft resistance acting above point A. c Is R i a static resistance force? The resistance force between point A and B includes both static and dynamic resistance components.

The Case Method, Wave Mechanics, Theory and Derivations: Results of Example Problems

263

Answer to Example Problem 5: Calculating total Resistance In Example Problem 3 determine the total resistance R Total a from Wave-down and Wave-up and recalling eqn A.4.3b R Total = F d1 + F u2 = 3886kN +  – 1986kN  = 1900kN R Total = F d1 + F u2 = 868.6kip +  – 443.6kip  = 425kip b from the corresponding individual force and velocity values. use the data points identified in the Example Problem 3, i.e., with time 1 at the first major peak. recalling eqn A.4.4

R Total

m m m 3772kN  ----  1.0 ---- – 1.0 ----  Ft + Ft  Z  vt – vt  s s s  4000kN +  – 200 kN   1 2 1 2 = ------------------------- + -------------------------- = --------------------------------------------------------- + ------------------------------------------------------------------- = 1900kN 2 2 2 2

R Total

· · ft ft ft 253.7kip  ---  3.3 --- – 3.3 ---  Ft + Ft  Z  vt – vt  s s s  900kip +  – 50k ip   1 2 1 2 = ------------------------- + -------------------------- = ----------------------------------------------------- + ------------------------------------------------------------------- = 425kip 2 2 2 2

The Case Method, Wave Mechanics, Theory and Derivations: Results of Example Problems

264

Answer to Example Problem 6: Calculating Ru for t1 at First Peak Velocity a Using the expressions for Wave-down and Wave-up in terms of the measured force and velocity at times t 1 and t 2 , rewrite eqn A.4.11b in terms of the measured force and velocity. R Static =  1 – J c F d1 +  1 + J c F u2 Ft – vt Z Ft – vt Z 1 1 2 2 R Static =  1 – J c  ---------------------- +  1 + J c  ---------------------2 2 1 R Static = ---  F t + v t Z + F t – v t Z – J c  F t + v t Z – F t + v t Z   1 2 2 1 1 2 2 2 1 b In Example Problems 3 and 5, for times t 1 and t 2 identified, calculate the toe velocity and, assuming a Case Damping factor J c = 0.2 , calculate the damping force and determine the static capacity by subtracting the damping force from the total resistance. 2  F d1  – R Total 2  3886kN  – 1900kN = 1.56 m = -----------------------------------------------------v b = -----------------------------------------s m Z 3772kN  ---s 2  F d1  – R Total  868.6kip  – 425kip = 5.17 ft = 2-----------------------------------------------------v b = ----------------------------------------s ft Z 253.7kip  --s

m m R Dynamic = J c v b Z = 0.2  1.56 ----  3772kN  ---- = 1177kN  s s ft ft R Dynamic = J c v b Z = 0.2  5.17 ---  253.7kip  --- = 262.3kip  s s 

R Static = R Total – R Dynamic = 1900kN – 1177kN = 723kN R Static = R Total – R Dynamic = 425kip – 262.3kip = 162.7kip c

Discuss the R Static result obtained. How sensitive is it to the damping factor J c (for example, calculate R Static also for J c = 0.3 )? Why would the static resistance be so sensitive?

Increasing the damping factor from 0.2 to 0.3 would increase the damping resistance from 1150 to 1725 kN and therefore reduce RU to 175 kN. A further increase of Jc would make the RU negative (note that the Case Method will not allow negative resistance forces and just set the result to zero.) This high RU sensitivity to damping can be attributed to the high velocity return at 2L/c, being as high as the impact velocity and, therefore a relatively low RTL (less than ½ of Fd1).

The Case Method, Wave Mechanics, Theory and Derivations: Results of Example Problems

265

Answer to Example Problem 7: Estimates of Shaft Resistance and End Bearing

Force Velocity

WaveUp WaveDown

½SFT=51%Fd1

t1

t2

SI

English

Pile Size

450 mm

18 in

Specific Weight 

23.6 kN/m3

150 lb/ft3

Length Below Sensors (LE)

23.5 m

77 ft

Time 1

22.7 ms

22.7 ms

Time 2 (t1+2L/c)

35.3 ms

35.3 ms

Force at t1 (FT1)

2790 kN

630 kips

Force at t2 (FT2)

650 kN

150 kips

velocity at t2 (VT2)

-0.14 m/s

-0.45 ft/s

With the measurements and information shown above taken on a uniform square prestressed concrete pile, calculate: a The cross-sectional area (A): 2

A =  0.45m  = 0.2025m 2

A =  18in  = 324in

2

2

b The wavespeed of the pile (c): m 2  23.5m  2L c = ------------------- = ------------------------------------------------ = 3730 ---s  t2 – t1   35.3ms – 22.7ms  ft 2  77ft  2L c = ------------------- = ------------------------------------------------ = 12220 --s  t2 – t1   35.3ms – 22.7ms 

The Case Method, Wave Mechanics, Theory and Derivations: Results of Example Problems

266

c The elastic modulus (E): 3

2  2 23.6kN/m  m 2 E = c = --- c = --------------------------  3730 ---- = 33470Mpa 2 g s 9.81m  s

1ft ft 2 2  2 150pcf 1kip E = c = --- c = --------------------2-  ------------------  --------------  12220 --- = 4831ksi s g 32.2ft/s 1000lb 144in d The pile impedance (Z): 2

m  33470Mpa   0.2025m  Z = EA -------- = --------------------------------------------------------------- = 1817kN  ---s c 3730m  s 2

ft  4831ksi   324in  Z = EA -------- = ------------------------------------------------ = 128.1kip  --s c 12220ft  s e The velocity at time 1 (VT1): because we see that the force and velocity stay proportional through the initial peak, t 1 Ft m 2790kN v t = -------1 = ----------------------------- = 1.54 ---1 s m Z 1817kN  ---s Ft ft 630kip v t = -------1 = ------------------------------- = 4.92 --1 s ft Z 128.1kip  --s f

The force Wave-down at time 1 (WD1): · m  2790kN  +  1.54m/s   1817kN  ---- Ft + vt Z  s 1 1 = ------------------------ = ------------------------------------------------------------------------------------------- = 2790kN 2 2

F d1

F d1

ft ft  630kip  +  4.92 ---  128.1kip  --- Ft + vt Z  s s  1 1 = ------------------------ = ---------------------------------------------------------------------------------------- = 630kip 2 2

g The force Wave-up at time 2 (WU2):

F u2

m  650kN  –  – 0.14 m/s   1817kN  ---- Ft – vt Z  s 2 2 = ----------------------- = ------------------------------------------------------------------------------------------- = 452.2kN 2 2

F u2

ft ft  150kip  –  – 0.45 ---  128.1kip  --- Ft – vt Z  s s  2 2 = ----------------------- = ------------------------------------------------------------------------------------------ = 103.8kip 2 2

h The total resistance at time 1 (RTL): R Total = F d1 + F u2 = 2790kN + 452.2kN = 3242kN R Total = F d1 + F u2 = 630kip + 103.8kip = 733.8kip

The Case Method, Wave Mechanics, Theory and Derivations: Results of Example Problems

267

i

The Static resistance at time 1(assume J c = 0.5) (RP5) R Static =  1 – J c F d1 +  1 + J c F u2 =  1 – 0.5   2790kN  +  1 + 0.5   452kN  = 2073kN R Static =  1 – J c F d1 +  1 + J c F u2 =  1 – 0.5   630kip  +  1 + 0.5   104kip  = 471kip

j

The total shaft resistance at time 1 (SFT):

if we extrapolate the Wave-up curve to t2 it would be approximately 51% of Fd1, thus: SFT = 2  F d1   51%  = 2  2790kN   51%  = 2846kN SFT = 2  F d1   51%  = 2  630kip   51%  = 642.6kip k The static shaft resistance at time 1(assume J c = 0.5) (SF5): R Static 2073kN RP5 SF5 = SFT  ---------------- = SFT  ----------- =  2846kN   -------------------- = 1820kN  3242kN  RP0  R Total  R Static RP5 471kip SF5 = SFT  ---------------- = SFT  ----------- =  642.6kip   ---------------------- = 412.5kip R Total RP0 733.8kip l

The estimated end bearing at time 1(assume J c = 0.5) (EB5): EB5 = RP5 – SF5 = 2073kN – 1820kN = 253kN EB5 = RP5 – SF5 = 471kip – 412.5kip = 58.5kip

m Would the RAU method be appropriate? No, there is too much shaft resistance. n Would this be a case benefiting from the unloading correction? Possibly, because the velocity becomes negative prior to 2L/c Note: Since the maximum resistance does not occur at t 1 , the EBR value which relates to the RMX method will be different from your estimate for t 1

The Case Method, Wave Mechanics, Theory and Derivations: Results of Example Problems

268

Answer to Example Problem 8: Tension Stress Calculation

100%

WaveUp WaveDown

t1

t2

In the above Wave-down and Wave-up record, determine the following values: a Minimum (maximum tension) Wave-up as a percentage of maximum Wave-down; minFu = -45% b Minimum Wave-down as a percentage of maximum Wave-down; minFd = 0% c Relative distance from the pile top where maximum net tension occurs. x = 23% of LE Based on (a) and (b), the maximum tension in the pile CTN = 45 – 0 = 45% of the maximum Wave-down.

The Case Method, Wave Mechanics, Theory and Derivations: Results of Example Problems

269

Answer to Example Problem 9: Damage Assessment

Force Velocity

L

x=0.5L

Wave Up Wave Down

Fd1=100%

Fu1=43% ½Rx=7% a For the above record of a 35.7 m (117 ft) long (below sensors) steel pile, calculate the depth of damage and its severity. Assuming F u1 is 100% we can approximately scale the resistance wave is F uR = 7% and R x is therefore 14% The damage tensile wave is F u1 = -43% , therefore: 100 – 1.5  14  +  – 43   = 36 = 25%  = ------------------------------------------------------------------- 100 – 0.5  14  –  – 43   136 The damage is located approximately 50% of LE (i.e., 17.2m or 56.2 ft) below the sensors or 19.5 (64.2 ft) below pile top. b What could be the reason for such a clear damage reflection in a steel pile? For steel piles, this could be an indication of a broken weld or a sharp bend in the pile. Of course, if the damage happened on a hard layer at a depth corresponding to the damage length, this could also be a collapsed (accordion type damage) pile bottom. In any case, the ß value would not be a true indication of Z2.

The Case Method, Wave Mechanics, Theory and Derivations: Results of Example Problems

270

Answer to Example Problem 10: Hammer Performance a Calculate the stroke of a diesel hammer if the hammer runs at 38 blows/minute. 2

60s  min 2 g 2 9.81m  s h =  --- T – h L =  -------------------------  ---------------------------------- – 0.1m = 2.96m 8 38blow  min 8 2

60s  min 2 g 2 32.2ft  s h =  --- T – h L =  ------------------------  ---------------------------------- – 0.3ft = 9.7ft 8 38blow  min 8 Consider a hammer with a 44.5 kN (10 kip) ram with a rated stroke of 1.0 m (3.3 ft) and an observed impulse (MFO) of 17.8 kN-s (4.00 k-sec) and EMX of 24.4kJ (18.0 k-ft). Calculate the hammer’s: b Rated energy, ER = 44.5kN  1m  = 44.5kJ ER = 10kip  3.25ft  = 33.0kip – ft c Rated impact velocity, v ir =

2gh =

m m 2  9.81 ----2-  1.0m  = 4.42 ---  s s

v ir =

2gh =

ft ft 2  32.2 ----2-  3.3ft  = 14.6 --  s s

d Actual impact velocity, m 17.8kN – s v i = MFO -------------- = --------------------------------------------- = 3.92 ---s m mR  44.5kN  9.81 ---2  s ft 4.0kip – s v i = MFO -------------- = ----------------------------------------- = 12.8 --s ft  mR  10kip  32.2 ---2  s e Kinetic energy, m 2 m   44.5kN  9.81 ---- 3.92 ---- 2   s s E k = ------------- = --------------------------------------------------------------------= 34.9kJ 2 2 2 mR v i

2

ft   ft  10kip  32.2 ---- 12.8 --- 2   s s E k = ------------- = ----------------------------------------------------------------- = 25.5kip – ft 2 2 2 mR v i

f

Hammer efficiency, E 25.2kip – ft  h = ------k- = 34.9kJ ----------------- = ----------------------------- = 78% ER 44.5kJ 33.0kip – ft

g Transfer ratio (efficiency)? E 18.0kip – ft  t = ------t- = 24.4kJ ----------------- = ----------------------------- = 55% ER 44.5kJ 33.0kip – ft

The Case Method, Wave Mechanics, Theory and Derivations: Results of Example Problems

Appendix B: Quick Set-up Guide B.1 Foreword The Pile Driving Analyzer® (PDA) collects, processes and stores strain and acceleration records taken during pile driving. The PDA 8G can currently record up to 8 channels of data (strain and acceleration) although 4 channels (2 strain and 2 acceleration) are sufficient for most projects. The measured dynamic data is evaluated in closed form according to the Case Method for capacity, driving stresses, hammer transferred energy, and pile integrity. The data is also used for CAPWAP® analysis. The following is a brief step-by-step procedure on the operation of the 8G. In writing this step-by-step procedure, it is assumed that the operator understands the basic applications, principles and limitations of this type of test. This procedure is meant to aid the relatively inexperienced user in the general operation of the PDA and does not cover all aspects of dynamic testing or all PDA features. Other sections of the PDA manual cover these topics in greater detail and it is strongly recommended that the user read the entire PDA manual.

B.2 Pile Preparation and Sensor Attachment Pile preparation involves preparing holes near the pile top (you must drill one hole for each accelerometer and two holes for each strain transducer). When drilling concrete piles, use the drill template to ensure that the holes are drilled exactly 3 inches (76 mm) apart for strain transducer attachment (drill the first hole, install a threaded anchor firmly, attach the drill template and then drill the second hole). For steel pipe piles, the holes should be drilled and then tapped. For steel H-piles, clearance holes are drilled in the center of the web to allow for bolts with nuts. One additional hole is often needed for main cable support. Before attaching to the pile, the balancing of the strain transducers and accelerometers should be checked. Unbalanced transducers should be repaired, adjusted, replaced or sent back to Pile Dynamics for repair and recalibration. All strain transducers and

Quick Set-up Guide: Foreword

272

accelerometers should be checked by tapping each sensor after selecting all channels as triggers in the sensor page of file setup. A calibration test should be performed by touching the standby accept button

on the Toolbar, followed by the calibration

pulse button . After verifying that all equipment is working properly, disconnect the main cables from the PDA and attach the sensors to the pile. The sensors should be bolted on diametrically opposite sides of the pile, at least two (2) pile diameters below the pile top, and equidistant about the neutral axis to minimize the effects of eccentric impacts or high local stresses. However, attaching the sensors three to four (3 to 4) pile diameters below the pile top is preferable when the final pile length above grade allows (except for regularly reinforced concrete where attaching near the top is preferred due to normal minor tension cracking). Use a flat washer with every bolt. It is a good idea to note the location of each strain transducer when attached to the pile. In this way, if the hammer is impacting eccentrically, you may aid the contractor in adjusting the hammer alignment. For H piles, sensors can be attached to the pile web prior to lifting the pile for driving. The accelerometers and one strain sensor can be mounted on one side with the cable, and the other strain sensor on the opposite side of the web with its cable passed through a flame cut hole in the web so the cable is not exposed. This flame cut hole is only needed when collecting data with wires. Using the wireless boxes eliminates the need for this hole, as one strain, one accelerometer and one wireless box can be attached on each side of the web. For concrete, timber and steel pipe piles, PDI offers “sensor protectors” which are placed over the sensors and secured with a belt strap so the sensors can be attached on the ground and then the pile lifted to avoid having to attach sensors in the air. This can significantly improve the efficiency of testing by reducing the delays associated with climbing the leads or ascending in a lift to attach sensors. It also allows the testing engineer to personally assure the proper attachment of the sensors rather than relying on the pile crew members. For restrikes, the piles can be prepared and the sensors attached at most any convenient location above ground level. To increase gage life, strain transducers should never be stepped on or be impact any hard surfaces such as the pile or leads as this may impose deformations. Accelerometers should never by subjected to any severe motions (i.e. motions perpendicular to their measuring axis). The better the handled, the longer they will last.

allowed to permanent horizontal sensors are

B.3 Equipment Set-up and Program Initialization For safety reasons, keep the PDA away from the hammer and pile. Safety is your first priority and pile sites can be hazardous. Also, protect the PDA from inclement weather. Although the PDA has been designed for field conditions, damage may occur if left unprotected. It is always a good idea to verify that all equipment is working before connecting the sensors to the pile. Connect all sensors to the “spreader cable” (special connection cable

Quick Set-up Guide: Equipment Set-up and Program Initialization

273

combining four sensors into a single connector) and the spreader cable to the 19-pin main cable(s). The main cable is then connected to the PDA. The main cable may be connected to either main cable input on the PDA. In 8 channel operation, connect two separate cables to both inputs on the PDA 8G. 1 The PDA 8G contains a replaceable Lithium-Ion battery, which provides runtime of approximately 4-hours. A battery indicator on the main screen offers the user a time frame for remaining battery life. If long periods of daily use are anticipated, then a second battery should be charged and ready to swap in. The PDA 8G should be completely powered off to complete this battery switch. If AC power is used, it is recommended that the voltage is checked with a voltmeter before turning on the PDA. Power up the PDA 8G by pressing the “on/off ” switch. 2 After turning on the PDA, open the application “PDA-S.exe,” PDA for Windows. 3 PDA-S instructions- On the Man Menu Window, several options will appear (Figure B-1). Data may be collected in either Collect Wire or Collect Wifi mode, while collected data may be inspected in the Review Mode.

Figure B.1: PDA-S Startup Window a) If collecting data with wires, proceed with the Collect Wire Mode. At this point, gages should be attached to the pile to be tested, and the user may continue to setting up the Project and Test Information. b) If collecting data with the Wifi boxes, proceed with the Collect Wifi Mode. This also assumes the Wifi Radios have been set up, and gages are already attached to the pile to be tested. Project and Test information will similarly be requested after entering this mode.

Quick Set-up Guide: Equipment Set-up and Program Initialization

274

To set up the Wifi radios, select “Configure Wifi” on the Main Menu. A new screen will open that will allow Wifi radios to be registered for use with the respective PDA 8G (Figure B-2).

Figure B.2: Wifi Box Registry To register a Wifi radio for use, enter in the respective Wifi radio serial number, in the “Add Radio” input box and select this button. The entered serial number will populate the “Registered Radios” list. From there, highlight the newly entered serial number, and select the right arrow (play button) to add the selected Wifi radio to the “Valid Radios for Connection” list. Continue this process until all radios have been registered, and added to the “Valid Radios for Connection” box. Note that once registered, the Wifi radio will be saved for future use with the respective PDA 8G. Since the PDA 8G will scan for and accept data from any Wifi radio entered in the “Valid Radios for Connection” list, make sure only the necessary Wifi radios are selected for use. If a radio will not be utilized in the upcoming test, use the left arrow (rewind button) to remove the unwanted Wifi radio. When finished, select Done, and return to the Main Menu. c. To review previously collected data, enter review mode and select a file to be reviewed. This process will not be discussed in this appendix. d. From the Main Menu, System Information may be viewed in “Settings,” while “About” brings up software information. “Exit Program will return the user to the desktop and “Shut Down” will close the PDA-S program and power off the PDA 8G.

Quick Set-up Guide: Equipment Set-up and Program Initialization

275

B.4 Procedure to Enter Project and Test Information This section will cover entering project information, and will be similar for both Collect Wire, and Collect Radio modes. The following steps begin immediately after entering either mode. 1 First, check the unit specification by toggling to the desired unit system in the lower left hand corner. In addition, abbreviations in the PDA-S software will sometimes be as follows: “E” for English, “M” for metric, “SI” for SI units, and “MKS” for the meter/ kilogram/second system. While in any tab, Review may be selected to show a summary of the input Project and Test information. 2 Next, enter in project information such as the Project Name, Pile Name, Test Description and Operator Name (Figure B-3). The collection mode may also be toggled between Normal and Restrike.

Figure B.3: Project Tab

Quick Set-up Guide: Procedure to Enter Project and Test Information

276

3 After entering project information, select on the “Pile” tab at the top of the screen and enter in pile information (Figure B-4). Total Pile Length (LT ), Length of Pile below Gages (LE) and Pile Penetration into Ground (LP) should be input along with Pile Area (AR), Splice Data and Pile Inclination (AI). Pile Material Properties may be manually entered for Modulus (EM), Unit Weight (SP) and Wavespeed (WS) or by selecting the appropriate material and using the estimated values from the software. The user must confirm wave speed, specific weight and modulus values are appropriate for their test. Default increments for recording the pile penetration during driving should be used unless the pile is marked with different penetration lengths.

Figure B.4: Pile Tab

Quick Set-up Guide: Procedure to Enter Project and Test Information

277

4 On the “Sensor” tab, the connected Gages will display somewhat differently depending on Wire or Wifi Mode. Figure B-5 presents the Sensor tab in Collect Wifi Mode, where each connected radio will be tabulated, followed by the connected gages. The supplied gages are “smart” and will therefore populate the sensor list with their type (i.e. PR, PE, ST for piezoresistive accelerometers, piezoelectric accelerometers and strain transducers, respectively), serial number, and calibration. At least one sensor must be selected as a trigger for each Wifi radio, and to accomplish this, simply select the “trigger” box so that a check mark appears. To view additional connected radios, select an alternate radio from the tab list. For Collect Wire Mode, the Sensor tab will appear similarly, although instead of appearing as multiple radios, the user will be notified of the main cable port that has paired radios. All other features remain the same, as in this mode, the 8G will again pick up the “smart” gages.

Figure B.5: Sensor Tab

Quick Set-up Guide: Procedure to Enter Project and Test Information

278

5 On the “Hammer” tab, select the hammer for use with the current pile (Figure B-6). Either choose the hammer from the “Hammer from List” button, or create and use a Custom Hammer.

Figure B.6: Hammer Tab

Quick Set-up Guide: Procedure to Enter Project and Test Information

279

6 Next move to the “Sample” tab to select data sampling quantities (Figure B-7). The sample time affect the length of time for each record while the frequency adjusts the rate of sampling. Typically 200-ms and 10-KHz are sufficient. A pretrigger buffer may also be adjusted for diesel hammers, and allows for data collection in the time of precompression.

Figure B.7: Sample Tab

Quick Set-up Guide: Procedure to Enter Project and Test Information

280

7 Next, select the “Data Limits” tab as shown in Figure B-8. This will flag output quantities when either collecting or reviewing data that are outside the ranges specified. Capacity, measured stresses, and hammer performance values may be selected from this screen, and may also be entered during collection modes well.

Figure B.8: Data Limits Tab 8 After completing the data input, “Review” may be selected to view a summary screen, while the “Collect” button may be pressed to enter data collection mode.

B.5 Procedure for Collecting and Evaluating Data Select the calibration pulse button as shown in figure B-9 (Cal Pulse icon with one square and one triangular shaped records). This will also place the 8G in “Accept” mode. Note the 3-boxes along the left of the plot section of the screen. These will be filled with data quality monitoring parameters that will be highlighted if certain ranges are exceeded. On the right of the plot section, 11-boxes containing data reviewing parameters exist, and allow the user to switch scales (TS), plots following procedure is recommended:

, records () and other items. The

1 The procedure for collecting and evaluating data is essentially the same for all pile types. However, for concrete and timber piles the wave speed must be measured (or checked if it was measured with the “free pile solution”) at the beginning of driving. Ask the pile driving contractor to apply 5 to 10-impacts and then stop. These impacts should be recorded so that they can be reprocessed. Choose one of these impacts and determine the wave speed by choosing TS from the tool bar and matching the T2 time with the toe reflection using the left and right arrow icons. You may also need to change the time scale TS or with a pinching motion with two fingers to expand the records to

Quick Set-up Guide: Procedure for Collecting and Evaluating Data

281

more clearly display the 2L/c time for wave speed determination). Set the elastic wave speed WS equal to the measured wave speed by touching the upper left pile information box. Note the elastic modulus (EM) will change as well.

Figure B.9: Collect Mode - Calibration Pulse 2 Check proportionality of force and velocity. Good proportionality is required for good quality data and verifies that sensor calibrations and WS were entered correctly. The following are possible causes of non-proportional data (the data is generally considered “proportional” if the difference between force and velocity is within 5%):

Incorrect sensor calibration inputs a Severe bending causing the “average” of the strain to be distorted (Try to improve by realigning hammer and pile) b Incorrect wave speed input (WS) or wave speed at gage location different from the overall (average) wave speed determined from the 2L/c time of reflection (concrete/ timber piles only) c Non-active sensor(s), loose sensors or sensors not axially aligned on pile (cable down) d Non uniform pile (reductions in impedance or increases in impedance). e High skin friction near the sensor location. f Precompression from diesel hammers. Items e) and f) above can be “normal” pile or soil responses and therefore does not indicate “bad” data. If the data is not “proportional” due to reasons other than e) and f),

Quick Set-up Guide: Procedure for Collecting and Evaluating Data

282

it is essential that the cause be investigated and the appropriate corrective measure be taken to improve the data. “Bad” data will result in inaccurate or unreliable results. Another way to evaluate is by inspecting Wave Up and seeing it is smooth (no steps) through the impact zone. A force and velocity records is displayed in Figure B-10.

Figure B.10: Collect Mode - Data Collection, Proportionality Evaluation 3 Check consistency of force and velocity data from blow to blow. Inconsistent force records may indicate a “loose” or electronically inactive strain transducer. Inconsistent velocity data or a final displacement which does not correlate well with the blow count may indicate an “unstable” accelerometer. Verify from time to time that all channels are active and working properly by clicking the Ind V or Ind F graph selections, toggling sensors as active and in active by clicking on a specific transducer serial number in the

menu. If a sensor malfunctions, driving should be stopped and the sensor replaced (make sure the calibration number for the replacement sensor is also correctly entered for traditional sensors or correctly read for smart sensors). If it is not feasible to stop driving, the PDA can often be operated with only one active acceleration channel. However, it is extremely important that at least two strain transducers or an even number of strain transducers be active at all times to avoid erroneous data. 4 Monitor Quantities calculated assuming linear elastic uniform piles in the Output Quantities list. PDA-s includes a list of default suggested quantities for the hammer and pile material input. Quantities should include at least the following values: transferred energy EMX, maximum compressive pile top stress CSX (and CSI for bending), for concrete piles, maximum tension stress TSX, hammer stroke (single acting diesel only) STK, hammer operating rate BPM, and the appropriate capacity computation (iCAP®,

Quick Set-up Guide: Procedure for Collecting and Evaluating Data

283

RMX, RA2, RAU, RSP, RSU). Also note the integrity factor BTA should be monitored in the second bottom window from the left side of the screen of alert quantities. a Stresses: The PDA determines average compression stress at the transducers with CSX (computed from FMX/AREA). The maximum stress from any individual transducer is given by CSI. A calculated estimate of the stress at the pile toe is given by CSB (non-uniform contact pressures on rock are NOT considered). The tension stress below the sensor location is given by TSX (computed by CTN/AREA). The tension stress TSX should be monitored for concrete piles only. b Hammer Performance: Compute the transfer efficiency EMX/Rated Energy (ETR) and compare to typical transfer efficiencies given by the hammer performance. c Damage: Damage is generally indicated by a “sharp” reduction in the wave-up curve or a “sharp” velocity increase relative to the force before the 2L/c time. If the pile is non-uniform or the wave-up decreases, the PDA may indicate damage but the pile may not be damaged. The damage severity is given by BTA and the location by LTD. Always check manually for monotonic increase in wave-up during the first 2L/c time after initial impact rise as the BTA computation may not detect damage near the pile top. d Capacity: The PDA estimates the capacity at the time of testing only which is often a reduced strength during driving. For an estimate of the “long term” capacity, piles should be tested during a restrike sometime after initial drive. For comparison to static testing, the restrike should be performed after similar waiting periods as for the static testing. It is strongly suggested that the capacity also be evaluated with CAPWAP. If blow count is very high (very low set/blow), the capacity may not be fully mobilized. If possible (stresses acceptable), increase the energy and force inputs and try again.

B.6 Sensor Removal After driving is completed, place the PDA in STANDBY with the Standby toggle button / . Then select “Done” to end the current collection operation. The file will be automatically saved to the project directory on the PDA 8G. The user should now remove the sensors from the pile as soon as possible to reduce the risk of damage to the sensors, cables or Wifi Radios. Always take caution not to mishandle the sensors.

B.7 Exiting the Program Exit the program by selecting “Exit” from the PDA-S Main Menu. This will take you back into Windows.

B.8 Procedure for Data Storage After data collecting is completed, the recorded digital data is saved to the PDA 8G as mentioned. This data may then be transferred to a USB Memory Stick after exiting the PDA-S program. A detailed discussion of that process is not covered here, as it is performed similarly to typical data transfer with personal computers. Data is stored in the user specified directory on the PDA 8G. Saved files appear in named project directories.

Quick Set-up Guide: Sensor Removal

284

Backup files are stored in real time, on a blow to blow basis in the folder C:\Users\PDI8G\Documents\PDIDataFullBackup.

B.9 Data Reporting The reports should include but not be limited to (refer to ASTM D4945 for more information of report requirements) the following information: 1 Pile details 2 Hammer details 3 General soil description (include sample boring logs in Appendix) 4 Test sequence 5 Result summary including: a Representative graphic plots of force and velocity data as a function of time (end of drive, restrike, etc.). This can be selected by clicking the PDF button in the bottom right corner of PDA-s, or going to Views->HP Report View. b A tabulated and graphical summary using the PDIPLOT2 program c CAPWAP results 6 Conclusions and recommendations 7 Appropriate disclaimers

Quick Set-up Guide: Data Reporting

Appendix C: Drilling Guides The following illustrations give recommendations on various pile types for correct gage attachment.

Drilling Guides:

286

  7\SLFDO

$FFHOHURPHWHU 6WUDLQ*DJH

0DLQ&DEOH7UDQVPLWWHU 6XSSRUW$QFKRUV

6(&7,21$$

&DEOHG2SWLRQ 0DLQ&DEOHZLWK &DEOH+ROGHU

$FFHOHURPHWHU 6WUDLQ*DJH

: 

“7\SLFDO

:LGWK: 

   “ 

$  “ 

$

   “ 

7UDQVPLWWHURU 0DLQ&DEOH6XSSRUW 0RXQWLQJ+ROH

%

'(7$,/%

$OOKROHVDUH IRUXVHZLWKH[SDQGDEOHDQFKRUVWXGV RU [GHHSIRUXVHZLWKLQWHUQDODQFKRU

7KHPLQLPXPGLVWDQFHLV:JUHDWHUGLVWDQFHVDUH SUHIHUDEOHOLPLWHGRQO\E\SLOHSHQHWUDWLRQ  ',0(16,216$5(,1,1&+(6 72/(5$1&(6 )5$&7,21$/ $1*8/$50$&+ %(1' 7:23/$&('(&,0$/ 7+5((3/$&('(&,0$/

35235,(7$5