Contents
Introduction xviii
Foreword xxi
Notation xxii
Note xxiv
1 Principles of rock slope design 1
1.1 Introduction 1
1.1.1 Scope of book 2
1.1.2 Socioeconomic consequences of slope failures 3
1.2 Principles of rock slope engineering 4
1.2.1 Civil engineering 4
1.2.2 Open pit mining slope stability 5
1.3 Slope features and dimensions 8
1.4 Rock slope design methods 8
1.4.1 Summary of design methods 8
1.4.2 Limit equilibrium analysis (deterministic) 11
1.4.3 Sensitivity analysis 14
1.4.4 Probabilistic design methods 15
1.4.5 Load and Resistance Factor Design 20
2 Structural geology and data interpretation 22
2.1 Objectives of geological investigations 22
2.2 Mechanism of joint formation 24
2.3 Effects of discontinuities on slope stability 25
2.4 Orientation of discontinuities 25
2.5 Stereographic analysis of structural geology 27
2.5.1 Stereographic projection 27
2.5.2 Pole plots and contour plots 29
2.5.3 Pole density 31
2.5.4 Great circles 32
2.5.5 Lines of intersection 34
2.6 Identification of modes of slope instability 35
2.6.1 Kinematic analysis 37
2.6.2 Plane failure 38
2.6.3 Wedge failure 38
2.6.4 Toppling failure 39
2.6.5 Friction cone 39
2.6.6 Applications of kinematic analysis 40
2.7 Example Problem 2.1: stereo plots of structural geology data 43
2.8 Example Problem 2.2: slope stability evaluation related to structural geology 44
3 Site investigation and geological data collection 46
3.1 Planning an investigation program 46
3.1.1 Geology 47
3.1.2 Rock strength 48
3.1.3 Ground water 48
3.2 Site reconnaissance 48
3.2.1 Aerial and terrestrial photography 49
3.2.2 Geophysics 49
3.3 Geologic mapping 52
3.3.1 Line and window mapping 53
3.3.2 Stereogrammetric mapping of discontinuities 53
3.3.3 Types of discontinuity 53
3.3.4 Definition of geological terms 54
3.4 Spacing, persistence and roughness measurements 59
3.4.1 Spacing of discontinuities 60
3.4.2 Persistence of discontinuity sets 61
3.4.3 Roughness of rock surfaces 62
3.5 Probabilistic analysis of structural geology 64
3.5.1 Discontinuity orientation 64
3.5.2 Discontinuity length and spacing 65
3.6 Diamond drilling 67
3.6.1 Diamond drilling equipment 67
3.6.2 Diamond drilling operations 68
3.6.3 Core logging 69
3.6.4 Core orientation 71
4 Rock strength properties and their measurement 74
4.1 Introduction 74
4.1.1 Scale effects and rock strength 74
4.1.2 Examples of rock masses 75
4.1.3 Classes of rock strength 77
4.2 Shear strength of discontinuities 79
4.2.1 Definition of cohesion and friction 79
4.2.2 Friction angle of rock surfaces 81
4.2.3 Shearing on an inclined plane 81
4.2.4 Surface roughness 82
4.2.5 Discontinuity infilling 85
4.2.6 Influence of water on shear strength of discontinuities 88
4.3 Laboratory testing of shear strength 88
4.4 Shear strength of rock masses by back analysis of slope failures 90
4.5 Hoek–Brown strength criterion for fractured rock masses 92
4.5.1 Generalized Hoek–Brown strength criterion 95
4.5.2 Modulus of deformation 99
4.5.3 Mohr–Coulomb criterion 99
4.5.4 Rock mass strength 100
4.5.5 Determination of σ
3 max 100
4.5.6 Estimation of disturbance factor D 101
4.6 Rock durability and compressive strength 102
4.6.1 Slake durability 102
4.6.2 Compressive strength 104
4.7 Example Problem 4.1: analysis of direct shear strength test results 106
4.8 Example Problem 4.2: analysis of point load test results 107
5 Ground water 109
5.1 Introduction 109
5.2 The hydrologic cycle 110
5.3 Hydraulic conductivity and flow nets 111
5.3.1 Hydraulic conductivity 111
5.3.2 Porosity 113
5.3.3 Flow nets 113
5.4 Ground water flow in fractured rock 114
5.4.1 Flow in clean, smooth discontinuities 115
5.4.2 Flow in filled discontinuities 116
5.4.3 Heterogeneous rock 117
5.4.4 Anisotropic rock 118
5.4.5 Ground water in rock slopes 118
5.5 Measurement of water pressure 120
5.6 Field measurement of hydraulic conductivity 123
5.6.1 Variable head tests 124
5.6.2 Pumping test 126
5.7 Example Problem 5.1: Influence of geology and weather conditions on
ground water levels 127
6 Plane failure 129
6.1 Introduction 129
6.2 General conditions for plane failure 129
6.3 Plane failure analysis 129
6.3.1 Influence of ground water on stability 133
6.3.2 Critical tension crack depth and location 134
6.3.3 The tension crack as an indicator of instability 134
6.3.4 Critical slide plane inclination 136
6.3.5 Analysis of failure on a rough plane 137
6.4 Reinforcement of a slope 138
6.4.1 Reinforcement with tensioned anchors 138
6.4.2 Reinforcement with fully grouted untensioned dowels 139
6.4.3 Reinforcement with buttresses 140
6.5 Seismic analysis of rock slopes 141
6.5.1 Performance of rock slopes during earthquakes 141
6.5.2 Seismic hazard analysis 142
6.5.3 Ground motion characterization 143
6.5.4 Pseudo-static stability analysis 144
6.5.5 Newmark analysis 145
6.6 Example of probabilistic design 148
6.7 Example Problem 6.1: plane failure—analysis and stabilization 150
7 Wedge failure 153
7.1 Introduction 153
7.2 Definition of wedge geometry 154
7.3 Analysis of wedge failure 156
7.4 Wedge analysis including cohesion, friction and water pressure 157
7.5 Wedge stability charts for friction only 160
7.5.1 Example of wedge analysis using friction-only charts 170
7.6 Comprehensive wedge analysis 171
7.6.1 Data for comprehensive analysis 171
7.6.2 Computer programs for comprehensive analysis 174
7.6.3 Example of comprehensive wedge analysis 175
8 Circular failure 176
8.1 Introduction 176
8.2 Conditions for circular failure and methods of analysis 176
8.2.1 Shape of slide surface 177
8.2.2 Stability analysis procedure 178
8.3 Derivation of circular failure charts 180
8.3.1 Ground water flow assumptions 180
8.3.2 Production of circular failure charts 181
8.3.3 Use of the circular failure charts 182
8.4 Location of critical slide surface and tension crack 184
8.5 Examples of circular failure analysis 185
8.5.1 Example 1—China clay pit slope 185
8.5.2 Example 2—highway slope 186
8.6 Detailed stability analysis of circular failures 187
8.6.1 Bishop’s and Janbu’s method of slices 188
8.6.2 Use of non-linear failure criterion
in Bishop stability analysis 193
8.6.3 Example of Bishop’s and Janbu’s methods of analysis 193
8.6.4 Circular failure stability analysis computer programs 195
8.6.5 Three-dimensional circular failure analysis 196
8.6.6 Numerical slope stability analysis 196
8.7 Example Problem 8.1: circular failure analysis 197
9 Toppling failure 200
9.1 Introduction 200
9.2 Types of toppling failure 200
9.2.1 Block toppling 200
9.2.2 Flexural toppling 201
9.2.3 Block-flexure toppling 202
9.2.4 Secondary toppling modes 202
9.3 Kinematics of block toppling failure 204
9.3.1 Block shape test 204
9.3.2 Inter-layer slip test 204
9.3.3 Block alignment test 205
9.4 Limit equilibrium analysis of toppling on a stepped base 205
9.4.1 Block geometry 206
9.4.2 Block stability 208
9.4.3 Calculation procedure for toppling stability
of a system of blocks 210
9.4.4 Cable force required to stabilize a slope 210
9.4.5 Factor of safety for limiting equilibrium analysis
of toppling failures 211
9.4.6 Example of limit equilibrium analysis of toppling 211
9.4.7 Application of external forces to toppling slopes 213
9.5 Stability analysis of flexural toppling 214
9.6 Example Problem 9.1: toppling failure analysis 216
10 Numerical analysis 218
10.1 Introduction 218
10.2 Numerical models 220
10.2.1 Joint material models 221
10.2.2 Rock mass material models 221
10.3 Modeling issues 223
10.3.1 Two-dimensional analysis versus three-dimensional analysis 223
10.3.2 Continuum versus discontinuum models 225
10.3.3 Selecting appropriate zone size 226
10.3.4 Initial conditions 226
10.3.5 Boundary conditions 228
10.3.6 Incorporating water pressure 229
10.3.7 Excavation sequence 230
10.3.8 Interpretation of results 230
10.4 Typical stability analysis 231
10.4.1 Rock mass failure 231
10.4.2 Plane failure—daylighting and non-daylighting 233
10.4.3 Wedge failure—daylighting and non-daylighting 234
10.4.4 Toppling failure—block and flexural 234
10.4.5 Flexural buckling failure 237
10.5 Special topics 237
10.5.1 Reinforcement 237
10.5.2 Time-dependent behavior 239
10.5.3 Dynamic analysis 244
11 Blasting 245
11.1 Introduction 245
11.2 Mechanism of rock fracturing by explosives 246
11.3 Production blasting 247
11.3.1 Explosive properties 248
11.3.2 Bench height 249
11.3.3 Burden 250
11.3.4 Blast hole diameter 251
11.3.5 Nature of the rock 251
11.3.6 Sub-drill depth 252
11.3.7 Stemming 252
11.3.8 Hole spacing 253
11.3.9 Hole detonation sequence 253
11.3.10 Fragmentation 255
11.3.11 Evaluation of a blast 256
11.4 Controlled blasting to improve stability 257
11.4.1 Pre-shearing and cushion blasting 257
11.4.2 Drilling 259
11.4.3 Explosive load 259
11.4.4 Stemming 260
11.4.5 Spacing and burden 261
11.4.6 Hole detonation sequence 261
11.5 Blast damage and its control 262
11.5.1 Damage from ground vibration 262
11.5.2 Control of flyrock 270
11.5.3 Control of air blast and noise 270
11.6 Example Problem 11.1: blast design 273
11.7 Example Problem 11.2: controlled blasting design 274
11.8 Example Problem 11.3: blast damage control 275
12 Stabilization of rock slopes 276
12.1 Introduction 276
12.2 Causes of rock falls 277
12.3 Rock slope stabilization programs 279
12.3.1 Planning stabilization programs 279
12.3.2 Rock slope inventory systems 279
12.3.3 Hazard rating criteria 280
12.3.4 Database analysis of slope inventory 282
12.3.5 Selection of high priority sites 282
12.3.6 Selection of stabilization measures 283
12.4 Stabilization by rock reinforcement 286
12.4.1 Shear keys 287
12.4.2 Rock anchors 287
12.4.3 Reaction wall 301
12.4.4 Shotcrete 301
12.4.5 Buttresses 304
12.4.6 Drainage 304
12.4.7 “Shot-in-place” buttress 306
12.5 Stabilization by rock removal 307
12.5.1 Resloping and unloading 308
12.5.2 Trimming 308
12.5.3 Scaling 308
12.5.4 Rock removal operations 309
12.6 Protection measures against rock falls 309
12.6.1 Rock fall modeling 310
12.6.2 Ditches 312
12.6.3 Barriers 313
12.6.4 Rock catch fences and attenuators 316
12.6.5 Draped mesh 317
12.6.6 Warning fences 317
12.6.7 Rock sheds and tunnels 318
13 Movement monitoring 320
13.1 Introduction 320
13.2 Types of slope movement 322
13.2.1 Initial response 322
13.2.2 Regressive and progressive movement 322
13.2.3 Long-term creep 324
13.3 Surface monitoring methods 324
13.3.1 Crack width monitors 325
13.3.2 Surveying 326
13.3.3 Laser imaging 327
13.3.4 Tiltmeters 327
13.3.5 Global positioning system 327
13.3.6 Synthetic aperture radar 327
13.4 Sub-surface monitoring methods 327
13.4.1 Borehole probes 328
13.4.2 Time–domain reflectometry 328
13.4.3 Inclinometers 328
13.5 Data interpretation 328
13.5.1 Time–movement and time–velocity plots 329
13.5.2 Slope failure mechanisms 332
14 Civil engineering applications 334
14.1 Introduction 334
14.2 Case Study I—Hong Kong: choice of remedial measures for plane failure 334
14.2.1 Site description 334
14.2.2 Geology 334
14.2.3 Rock shear strength 335
14.2.4 Ground water 335
14.2.5 Stability analysis 335
14.2.6 Stabilization options 339
14.3 Case Study II—Cable anchoring of plane failure 341
14.3.1 Site description 341
14.3.2 Geology 342
14.3.3 Rock shear strength 342
14.3.4 Ground water 343
14.3.5 Earthquakes 344
14.3.6 Stability analysis 344
14.3.7 Stabilization method 345
14.3.8 Construction issues 347
14.4 Case Study III—Stability of wedge in bridge abutment 348
14.4.1 Site description 348
14.4.2 Geology 348
14.4.3 Rock strength 349
14.4.4 Ground water 349
14.4.5 Seismicity 350
14.4.6 External forces 350
14.4.7 Stability analysis 350
14.5 Case Study IV—Circular failure analysis of excavation for rock fall ditch 352
14.5.1 Site description 352
14.5.2 Geology 353
14.5.3 Ground water 353
14.5.4 Rock shear strength 353
14.5.5 Ditch and slope design 354
14.5.6 Construction issues 354
14.6 Case Study V—Stabilization of toppling failure 354
14.6.1 Site description 354
14.6.2 Geology 355
14.6.3 Rock strength 355
14.6.4 Ground water 355
14.6.5 Stability conditions 355
14.6.6 Stabilization method 356
15 Mining applications 357
15.1 Introduction 357
15.2 Example 1—porphyry deposits 357
15.2.1 Design issues 358
15.2.2 Engineering geology 358
15.2.3 Rock strength and competency 358
15.2.4 Hydrogeology 359
15.2.5 Slope stability analyses and slope design 359
15.3 Example 2—stratigraphically controlled deposits 361
15.3.1 Design issues 361
15.3.2 Engineering geology 361
15.3.3 Rock strength and competency 362
15.3.4 Hydrogeology 363
15.3.5 Structural domains 363
15.3.6 Kinematic analyses 363
15.3.7 Stability analyses 364
15.3.8 Slope design concepts 365
15.3.9 Preliminary design 367
15.4 Example 3—deep-seated deformation in a weak rock mass 368
15.4.1 Design and operational issues 368
15.4.2 Engineering geology 369
15.4.3 Rock strength and rock mass competency 370
15.4.4 Hydrogeology and slope depressurization measures 370
15.4.5 Slope stability analyses 371
15.4.6 Slope design and operational management 372
15.5 Example 4—overall slope design in a competent rock mass 372
15.5.1 Design aspects and issues 372
15.5.2 Engineering geology 373
15.5.3 Rock strength and competency 373
15.5.4 Hydrogeology 373
15.5.5 Slope performance 374
15.5.6 Slope stability analyses 375
15.5.7 Implementation and ongoing evaluation 375
15.6 Conclusions 376
Appendix I Stereonets for hand plotting of structural geology data 377
I.1 Introduction 377
I.2 Plotting poles 377
I.3 Contouring pole concentrations 377
I.4 Plotting great circles 377
I.5 Lines of intersection 378
Appendix II Quantitative description of discontinuities in rock masses 381
II.1 Introduction 381
II.2 Rock mass characterization parameters 381
II.2.1 Rock material description 381
II.2.2 Discontinuity description 383
II.2.3 Infilling description 389
II.2.4 Rock mass description 389
II.2.5 Ground water 392
II.3 Field mapping sheets 394
Appendix III Comprehensive solution wedge stability 398
III.1 Introduction 398
III.2 Analysis methods 398
III.3 Analysis limitations 399
III.4 Scope of solution 399
III.5 Notation 400
III.6 Sequence of calculations 400
Appendix IV Conversion factors 408
References 411
Index 425
