Book INJ Pre Exc 2016 en [PDF]

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Pre-Excavation Grouting in Hard Rock Tunneling

«Photo: courtesy of AF Spesialprosjekt, Tunnel Lofast, Norway».

Pre-Excavation Grouting in Hard Rock Tunneling

Acknowledgement This is now the 5th edition of this book of which the 1st edition was written by Knut F. Garshol, in 2003 and to which BASF acknowledges appreciation. The revisions of this book reflect the technical developments which have taken place in the field of pre-grouting in rock , as well as the commercial rebranding of the products which have taken place. Despite such changes, the challenges faced by tunnellers, miners, geologists, contractors and project owners have remained largely the same, but in some cases more complex as the boundaries of projects are pushed ever further with corresponding technological advancement. In addition some updates have been made and statements revised to reflect the changes and developments that have taken place over the previous 40 years within the underground excavation industry. The key principals of pre-excavation grouting practices remain unchanged however the personnel within the tunnelling and mining industry is in a constant flux and hence the continuation of this book to ensure that the valuable experiences gained by those before them are still available for the next generation. Special thanks to Hans Olav Hognestad for his continued valuable input with regard to content suggestions and corrections based on his extensive hands-on and practical experience. Numerous colleagues and external industry contacts have also contributed to the formation of this book and for these valuable contributions BASF is grateful.

Copyright © BASF Construction Chemicals Europe Ltd., 2016 5th edition, March 2016 All rights reserved. No part of this publication may be reproduced, stored in or introduced into a retrieval system, or transmitted, in any form or by any means, without the prior written permission of BASF Construction Chemicals Europe Ltd.

Index 1. INTRODUCTION

11

1.1. 1.2. 1.3. 1.4. 1.5. 1.6. 1.7.

Reasons for grouting in tunneling Short explanation of the subject Scope of the book Traditional cement based grouting technology Rationale for the increased use of pressure grouting Some comments about post-grouting New material technology allows time saving procedures

11 11 13 14 16 18 23

2.

GROUTING INTO ROCK FORMATIONS

25

2.1. 2.2. 2.2.1. 2.2.2. 2.2.3. 2.3. 2.4. 2.5. 2.6.

Particular features of rock in comparison with soil Handling of rock conductivity contrast Description of typical grout to refusal procedure Stable grout of micro cement using dual stop criteria Comparison of the two procedures «Design» of grouting in rock tunnels Fluid transport in rock Practical basis for injection works in tunneling Grout quantity prognosis

25 30 31 31 32 33 35 37 40

3.

FUNCTIONAL REQUIREMENTS

42

3.1. 3.2. 3.3. 3.4. 3.5. 3.6.

Influence of tunneling on the surroundings Conditions inside the tunnel Calculation of water ingress to tunnels Special cases Requirements and ground water control during construction phase Measurement of water ingress to the tunnel

42 44 45 48

4.

CEMENT BASED GROUTS

4.1. Basic properties of cement grouts 4.1.1. Cement particle size, fineness 4.1.2. Bentonite 4.1.3. Rheological behavior of cement grouts 4.1.4. Pressure stability of cement grouts 4.1.5. Use of high injection pressure 4.1.6. Grout setting characteristics

49 51

52 52 52 55 57 58 59 60

4.2. 4.3.

Durability of cement injection in rock Controlled accelerated setting of microcement grouts

5.

CHEMICAL GROUTS

5.1. Polyurethane resins 5.1.1. General 5.1.2. Master Builders Solutions® PU-products 5.1.3. Pumping equipment 5.2. Silicate grouts 5.3. Master Builders Solutions® colloidal silica 5.4. Acrylic grouts 5.4.1. Master Builders Solutions® acrylic products 5.5. Epoxy resins 5.5.1. Combined system polyurea-silicates 5.6. Bitumen (asphalt)

6.

BOREHOLES IN ROCK

6.1. Top hammer percussive drilling 6.2. Down the hole drilling machines 6.3. Rotary low speed drilling 6.4. Rotary high speed core drilling 6.5. Example for drill and blast excavation 6.5.1. Drilling of injection holes 6.5.2. Packer placement 6.5.3. Water pressure testing 6.5.4. Choice of injection materials 6.5.5. Mix design for MasterRoc MP® grouting 6.5.6. Accelerated cement grout 6.5.7. Pump pressure 6.5.8. Special measures 6.5.9. Injection procedure 6.5.10. Injection records 6.5.11. Cement hydration – waiting time 6.5.12. Other relevant issues 6.6. Example solution: hard rock TBM excavation 6.6.1. The Oslo Sewage Tunnel System 6.6.2. The Hong Kong Sewage Tunnel System 6.6.3. Comments on drilling and injection equipment 6.7. Cleaning of injection holes 6.8. Packers

61 63

65 66 66 68 68 69 70 71 73 73 73 74

76 76 79 80 80 80 81 83 83 83 84 85 85 85 86 87 88 88 89 90 92 93 94 96

6.8.1. Mechanical packers (expanders) 6.8.2. Disposable packers 6.8.3. Hydraulic packers 6.8.4. Standpipe techniques 6.8.5. Tube-a-manchet 6.8.6. Drill anchors 6.9. Probing ahead of the face 6.9.1. Normal approach 6.9.2. Computer supported logging

97 98 100 101 103 104 104 104 107

7.

110

HIGH PRESSURE GROUND WATER CONDITIONS

7.1. Basic problem 7.2. Features that will add to the problem 7.3. Consequences for the contractor 7.4. Consequences for the owner 7.5. Methods for handling water ingress 7.6. Practical procedure in high risk areas 7.6.1. Pumping system 7.6.2. Probe drilling 7.6.3. Injection 7.6.4. Special issues 7.7. Practical aspects 7.8. Equipment 7.9. Examples 7.9.1. Kjela hydropower project 7.9.2. Ulla Førre hydropower project 7.9.3. Holen hydropower project 7.10. Summary of lessons learned

110 110 111 111 112 113 113 113 114 114 114 115 116 116 117 118 119

8.

120

MAXIMUM PUMPING PRESSURE

8.1. Introduction 8.2. Basic background considerations 8.3. The low-pressure approach 8.4. The high-pressure approach 8.5. Summing up 8.6. The theory behind high pressure grouting

120 120 121 122 124 124

9.

EQUIPMENT FOR CEMENT INJECTION

126

9.1.

Mixing equipment

126

9.2. 9.3. 9.4.

Grout pumps Complete equipment systems Recording of grouting data

131 132 134

10.

METHOD STATEMENT FOR PRE-INJECTION IN ROCK

137

10.1. Drilling 10.1.1. General 10.1.2. Flushing of boreholes for injection 10.1.3. Length of boreholes 10.1.4. Number of holes, hole direction 10.1.5. Placing of packers 10.2. Injection 10.2.1. General 10.2.2. Mixing procedure 10.2.3. Use of accelerator in the grout 10.2.4. Injection pressure 10.2.5. Injection procedure 10.2.6. Injection records 10.3. Grout setting and time until next activity 10.4. Drilling of control holes 10.5. Measurement of water ingress in excavated parts of the tunnel 10.6. Decision-making flowchart, example criteria

11.

EXAMPLES OF RESULTS ACHIEVED

11.1. General 11.2. What is achievable? 11.3. Comparing shallow and deep tunnels 11.3.1. Some shallow hard rock tunnels in Sweden 11.3.2. Some shallow tunnels in the Oslo area, Norway 11.3.3. Deep situated tunnels 11.4. Sedrun access tunnel, Alp Transit Project, Switzerland 11.5. Bekkestua Road Tunnel, Oslo, Norway 11.5.1. Practical execution in the Bekkestua Tunnel 11.6. The Bjoroy sub-sea road tunnel 11.7. The Ormen Project, Stockholm, Sweden 11.8. Limerick main drainage water tunnel, Ireland 11.9. The Kilkenny main drainage tunnel, Ireland 11.10. West Process propane cavern project (WPPC), Norway 11.11. Recent project result

137 137 138 138 139 139 140 140 140 141 142 143 144 144 145 145 146

149 149 149 151 151 154 154 155 156 156 157 160 162 165 166 168

11.12. 11.13. 11.14. 11.15. 11.16. 11.17. 11.18.

Oset drinking water treatment plant, Oslo, Norway Arrowhead tunnels in Ontario, California, USA Deep Tunnel Sewerage System T-06, Singapore High speed railway Naples-Milan: Bologna City underpass The Ghomrud water tunnel project, Iran River Aare underpass, Bern, Switzlerland Maneri Bhali Phase II hydropower project, Himalaya

169 171 173 175 178 180 182

12.

BASF INJECTION MATERIALS 186

12.1. The MasterRoc MP® range of injection cements 12.2. Polyurethane grouts 12.2.1. MasterRoc® PU grouts for 1 component pumps 12.2.2. MasterRoc® PU grouts for 2 component pumps 12.3. Polyurea-silicate grouts 12.3.1. Foaming polyurea-silicate grouts 12.3.2. Non - foaming polyurea-silicate grouts 12.4. Acrylic grouts 12.5. Colloidal silica (mineral grout)

186 189 190 192 194 195 196 197 200

13. REFERENCES

207

1. INTRODUCTION 1.1.

Reasons for grouting in tunneling Tunnel excavation involves a certain risk of unexpected ground conditions. One of the risks is the chance of hitting large quantities of high pressure ground water. Smaller volumes of ground water ingress can also cause problems in a tunnel or its surroundings. Water is the most frequent reason for grouting the rock that surrounds tunnels. Ground water ingress can be controlled or handled by drainage, pre-excavation grouting and post-excavation grouting. Rock or soil conditions causing stability problems for tunnel excavation is another possible reason for grouting. Poor and unstable ground can be improved by filling discontinuities with grout material which has sufficient strength and adhesion.

1.2.

Short explanation of the subject Pressure grouting in rock is executed by drilling boreholes of a suitable diameter, length and direction into the bedrock, placing packers near the borehole opening (or using some other means of providing a pressure tight connection to the borehole), connecting a grout conveying hose or pipe between a pump and the packer, and pumping prepared grout by overpressure into the cracks and joints of the surrounding rock. In tunnel grouting there are two main methodologies to be considered: < P  re-excavation