Rock Mass Classification (eBook)

Front Cover 1
ROCK MASS CLASSIFICATION: A Practical Approach in Civil Engineering 4
Copyright Page 5
CONTENTS 9
PREFACE 7
CHAPTER 1. PHILOSOPHY OF QUANTITATIVE CLASSIFICATIONS 16
1.1 The Classification 16
1.2 Philosophy of Classification System 17
1.3 Management of Uncertainties 17
1.4 Present Day Practice 18
1.5 Scope of the Book 19
CHAPTER 2. SHEAR ZONE TREATMENT IN TUNNELS AND FOUNDATIONS 20
2.1 Shear Zone 20
2.2 Treatment for Tunnels 20
2.3 Treatment for Dam Foundations 22
CHAPTER 3. ROCK MATERIAL 25
3.1 Rock Material 25
3.2 Homogeneity and Inhomogeneity 25
3.3 Classification of Rock Material 27
3.4 Class l and II Rocks 27
3.5 Uniaxial Compression 28
3.6 Stability in Water 30
3.7 Classification on the Basis of Slake Durability Index 30
CHAPTER 4. ROCK QUALITY DESIGNATION 32
4.1 Rock Quality Designation (RQD) 32
4.2 Direct Method 32
4.3 Indirect Methods 33
4.4 Weighted Joint Density 35
CHAPTER 5. TERZAGHl'S ROCK LOAD THEORY 40
5.1 Introduction 40
5.2 Rock Classes 40
5.3 Rock Load Factor 40
5.4 Modified Terzaghi's Theory for Tunnels and Caverns 46
CHAPTER 6. ROCK MASS RATING (RMR) 49
6.1 Introduction 49
6.2 Collection of Field Data 49
6.3 Estimation of Rock Mass Rating (RMR) 53
6.4 Applications of RMR 54
6.5 Inter-relation Between RMR and Q 59
6.6 Precautions 59
CHAPTER 7. PREDICTION OF GROUND CONDITIONS FOR TUNNELLING 62
7.1 Introduction 62
7.2 The Tunnelling Conditions 63
7.3 Empirical Approach 65
7.4 Theoretical / Analytical Approach 74
7.5 Effect of Thickness of Weak Band on Squeezing Ground Condition 75
CHAPTER 8. ROCK MASS QUALITY (Q) - SYSTEM 77
8.1 The Q-System 77
8.2 The Joint Orientation and the Q-system 84
8.3 Updating of the Q-system 84
8.4 Collection of Field Data 85
8.5 Classification of the Rock Mass 87
8.6 Estimation of Support Pressure 87
8.7 Unsupported Span 95
8.8 Design of Supports 96
8.9 New Austrian Tunnelling Method (NATM) 99
8.10 Norwegian Method of Tunnelling (NMT) 101
8.11 Other Applications of the Q - System 102
CHAPTER 9. ROCK MASS NUMBER 107
9.1 Introduction 107
9.2 Inter-relation Between Q and RMR 108
9.3 Prediction of Ground Conditions 111
9.4 Prediction of Support Pressure 111
9.5 Effect of Tunnel Size on Support Pressure 114
9.6 Correlations for Estimating Tunnel Closure 116
9.7 Effect of Tunnel Depth on Support Pressure and Closure in Tunnels 117
9.8 Approach for Obtaining Ground Reaction Curve (GRC) 118
9.9 Coefficient of Volumetric Expansion of Failed Rock Mass 120
CHAPTER 10. ROCK MASS INDEX 123
10.1 Introduction 123
10.2 Selection of Parameters used in RMi 123
10.3 Calibration of RMi from Known Rock Mass Strength Data 124
10.4 Scale Effect 126
10.5 Examples (Palmstrom, 1995) 130
10.6 Applications of RMi 131
10.7 Benefits of Using RMi 132
10.8 Limitations of RMi 132
CHAPTER 11. RATE OF TUNNELLING 135
11.1 Introduction 135
11.2 Classification of Ground/Job Conditions for Rate of Tunnelling 136
11.3 Classification of Management Conditions for Rate of Tunnelling 136
11.4 Combined Effect of Ground and Management Conditions on Rate of Tunnelling 141
CHAPTER 12. SUPPORT SYSTEM IN CAVERNS 143
12.1 Support Pressure 143
12.2 Wall Support in Caverns 144
12.3 Roof Support in Caverns 146
12.4 Stress Distribution in Caverns 148
12.5 Opening of Discontinuities in Roof Due to Tensile Stress 148
12.6 Rock Reinforcement Near Intersections 148
12.7 Radial Displacements 149
12.8 Precautions 149
CHAPTER 13. STRENGTH ENHANCEMENT OF ROCK MASS IN TUNNELS 151
13.1 Causes of Strength Enhancement 151
13.2 Effect of Intermediate Principal Stress on Tangential Stress at Failure in Tunnels 151
13.3 Uniaxial Compressive Strength of Rock Mass 154
13.4 Reason for Strength Enhancement in Tunnels and A Suggested New Failure Theory 156
13.5 Criterion for Squeezing of Rock Masses 158
13.6 Tensile Strength Across Discontinuous Joints 158
13.7 Dynamic Strength of Rock Mass 159
13.8 Residual Strength Parameters 161
CHAPTER 14. STRENGTH OF DISCONTINUITIES 163
14.1 Introduction 163
14.2 Joint Wall Roughness Coefficient (JRC) 163
14.3 Joint Wall Compressive Strength (JCS) 165
14.4 Joint Matching Coefficient (JMC) 169
14.5 Angle of Internal Friction 169
14.6 Shear Strength of Joints 170
CHAPTER 15. SHEAR STRENGTH OF ROCK MASSES IN SLOPES 173
15.1 Mohr-Coulomb Strength Parameters 173
15.2 Non-Linear Failure Envelopes for Rock Masses 173
15.3 Strength of Rock Masses in Slopes 177
15.4 Back Analysis of Distressed Slopes 177
CHAPTER 16. TYPES OF ROCK SLOPE FAILURES 179
16.1 Introduction 179
16.2 Planar (Translational) Failure 179
16.3 3D Wedge Failure 179
16.4 Circular (Rotational) Failure 179
16.5 Toppling Failure (Topples) 181
16.6 Ravelling Slopes (Falls) 182
16.7 Effect of Height and Ground Water Conditions on Safe Slope Angle 184
16.8 Landslide Classification System 184
CHAPTER 17. SLOPE MASS RATING (SMR) 186
17.1 The Slope Mass Rating (SMR) 186
17.2 Slope Stability Classes 190
17.3 Support Measures 190
17.4 Modified SMR Approach 191
17.5 Case Study of Stability Analysis Using Modified SMR Approach 193
CHAPTER 18. LANDSLIDE HAZARD ZONATION 199
18.1 Introduction 199
18.2 Landslide Hazard Zonation Maps - The Methodology 200
18.3 A Case History 205
18.4 Proposition for Tea Gardens 214
CHAPTER 19. ALLOWABLE BEARING PRESSURE FOR BUILDING FOUNDATIONS 215
19.1 Introduction 215
19.2 Classification for Net Safe Bearing Pressure 215
19.3 Allowable Bearing Pressure 216
19.4 Coefficient of Elastic Uniform Compression for Machine Foundations 220
CHAPTER 20. METHOD OF EXCAVATION 222
20.1 Excavation Techniques 222
20.2 Assessing the Rippability 222
20.3 Rock Mass Classification According to Ease of Ripping 223
20.4 Empirical Methods in Blasting 225
CHAPTER 21. ROCK DRILLABILITY 228
21.1 Drillability and Affecting Parameters 228
21.2 Classification for Drilling Condition 230
21.3 Other Approaches 232
CHAPTER 22. PERMEABILITY AND GROUTABILITY 234
22.1 Permeability 234
22.2 Permeability of Various Rock Types 234
22.3 Permeability for Classifying Rock Masses 235
22.4 Permeability vs Grouting 236
22.5 Determination of Permeability 236
22.6 Grouting 237
CHAPTER 23. GOUGE MATERIAL 245
23.1 Gouge 245
23.2 Influence of Gouge Material 246
23.3 Shear Strength of Filled Discontinuities (Silty to Clayey Gouge) 249
23.4 Dynamic Strength 250
CHAPTER 24. ENGINEERING PROPERTIES OF HARD ROCK MASSES 252
24.1 Hard Rock Masses 252
24.2 Modulus of Deformation 252
24.3 Uniaxial Compressive Strength (UCS) 252
24.4 Uniaxial Tensile Strength (UTS) 253
24.5 Strength Criterion 253
24.6 Support Pressure in Non-squeezing/Non-Rock Burst Conditions 254
24.7 Half-Tunnels 254
CHAPTER 25. GEOLOGICAL STRENGTH INDEX (GSI) 257
25.1 Geological Strength Index (GSI) 257
25.2 Modified Strength Criterion 258
25.3 Mohr-Coulomb Strength Parameters 260
25.4 Modulus of Deformation 262
25.5 Selection of Rock Parameters for Intact Schistose 262
CHAPTER 26. EVALUATION OF CRITICAL ROCK PARAMETERS 265
26.1 Introduction 265
26.2 Critical Parameters 265
26.3 Parameter Intensity and Dominance 266
26.4 Classification of Rock Mass 268
26.5 Example for Studying Parameter Dominance in Underground Excavation for a Coal Mine with Flat Roof 269
26.6 Relative Importance of Rock Parameters in Major Projects 271
26.7 Application in Entropy Management 271
CHAPTER 27. INSITU STRESSES 273
27.1 Need for Insitu Stress Measurement 273
27.2 Classification of Geological Conditions and Stress Regimes 273
27.3 Variation of Insitu Stresses with Depth 275
Author Index 278
Subject Index 280