Geomechanics in soil, rock, and environmental engineering

560 Pages·2016·21.161 MB·English

by  Small, John Campbell

Geomechanics

IN SOIL, ROCK, AND
ENVIRONMENTAL ENGINEERING
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Geomechanics

IN SOIL, ROCK, AND
ENVIRONMENTAL ENGINEERING
JOHN C. SMALL
The University of Sydney, New South Wales, Australia
Boca Raton London New York
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Version Date: 20160120
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Contents
Preface xix
Acknowledgments xxi
1 Basic concepts 1
1.1 Introduction 1
1.2 Basic definitions 1
1.2.1 Submerged unit weight 3
1.3 Soil tests 4
1.3.1 Triaxial tests 4
1.3.1.1 Unconfined compression test 4
1.3.1.2 Unconsolidated undrained test 5
1.3.1.3 Consolidated undrained test with
pore pressure measurement 6
1.3.1.4 Consolidated drained test 6
1.3.1.5 Alternative failure plots 7
1.4 Direct shear tests 8
1.5 Consolidation tests 9
1.6 Permeability 12
2 Finite layer methods 15
2.1 Introduction 15
2.1.1 General concepts 15
2.2 Approximation of Fourier coefficients 19
2.3 Formulation 21
2.4 Solution procedure 22
2.5 Three-dimensional problems 23
2.6 Consolidation problems 25
2.7 Fourier transforms 26
2.8 Examples 28
3 Finite element methods 31
3.1 Introduction 31
3.2 Types of elements 31
v
vi Contents
3.2.1 Finding shape functions 32
3.2.2 Isoparametric elements 34
3.2.3 Infinite elements 35
3.2.4 Finite element meshes 36
3.3 Steady state seepage 37
3.3.1 Governing equation 37
3.3.2 Finite element formulation 38
3.3.3 Approximation of total head h 38
3.3.4 Finite element equations 39
3.3.5 Calculation of flows 39
3.3.6 Flow lines 40
3.3.7 Calculation of flow using the stream function 41
3.3.8 Determining the stream function 41
3.3.9 Pumping or extracting fluid 42
3.4 Stress analysis 42
3.5 Consolidation analysis 45
3.5.1 Effective stress analysis 45
3.5.2 Volume balance 47
3.6 Numerical integration 50
3.7 Elastic–perfectly plastic models 52
3.7.1 Formulation 52
3.7.2 Examples for a specific failure surface: Mohr–Coulomb 54
3.8 Work hardening models 55
3.9 Effective stress analysis using Cam Clay type models 56
3.9.1 Normally consolidated clay 58
3.9.2 Overconsolidated clay 59
3.10 Cam Clay type models 60
3.10.1 Cam Clay yield surface 60
3.11 Undrained analysis 63
3.12 Finite element analysis 65
3.12.1 Examples 67
Appendix 3A: Shape and mapping functions for various element types 68
Appendix 3B: Global matrix assembly and boundary conditions 73
Appendix 3C: Boundary conditions 74
4 Site investigation and in situ testing 77
4.1 Introduction 77
4.2 Exploration methods 77
4.3 Site investigation 78
4.4 Object of site investigation 78
4.5 Category of investigation 78
4.6 Planning an investigation 79
4.7 Preparing cost estimates for the work 80
4.8 Detailed exploration 80
4.9 Presentation of information (logs) 80
Contents vii
4.10 Excavation or drilling methods 81
4.10.1 Test pits 81
4.10.2 Excavations 81
4.10.3 Drilling 81
4.10.3.1 Hand augers 81
4.10.3.2 Wash borings 83
4.10.3.3 Rotary drilling 83
4.10.3.4 Auger boring 83
4.11 Sampling methods 86
4.11.1 Thin-walled sampler (or Shelby tube) 87
4.11.2 Split spoon sampler (SPT sampler) 88
4.11.3 Piston sampler 88
4.11.4 Air injection sampler 88
4.11.5 Swedish foil sampler 88
4.12 Rock coring 89
4.13 Field tests 90
4.14 Vane shear test 91
4.15 Standard penetration test 91
4.15.1 Equipment 92
4.15.2 Sampler 92
4.15.3 Drive hammer 93
4.15.4 Rods 93
4.15.5 Test procedure 94
4.15.6 Properties of sands 95
4.15.7 Properties of clays 96
4.15.8 Liquefaction 98
4.16 Pressuremeters 101
4.16.1 Types of pressuremeters 101
4.16.2 Interpreting test results 102
4.17 Dilatometers 103
4.17.1 Type of soil 105
4.17.2 Shear strength of clays 105
4.17.3 Other quantities 105
4.18 Cone penetrometers 106
4.18.1 Equipment 106
4.18.2 CPT equipment 107
4.18.3 CPTu equipment 107
4.18.4 Pushing equipment 109
4.18.5 Calibration 109
4.19 Interpretation of cone data 111
4.19.1 Soil classification 111
4.19.2 Relative density of sands 113
4.19.3 Friction angle of sands 114
4.19.4 Constrained modulus of sands 116
4.19.5 Young’s modulus of sands 116
4.19.6 Undrained shear strength of clays 116
viii Contents
4.19.7 Undrained modulus of clays 117
4.19.8 Permeability 118
4.20 Liquefaction potential 119
4.21 Geophysical methods 121
4.21.1 Seismic surveys 122
4.21.2 Reflection surveys 123
4.21.3 Seismic refraction 124
4.21.4 Rippability of rock 125
4.22 Resistivity 125
4.22.1 Electrical sounding method 128
4.22.2 Push-in resistivity instruments 129
4.23 Magnetic surveying 130
4.24 Ground probing radar 130
4.25 Seismic borehole techniques 130
4.25.1 Down-hole seismic testing 130
4.26 Cross-hole techniques 131
4.27 Other seismic devices 132
5 Shallow foundations 135
5.1 Introduction 135
5.2 Types of shallow foundations 135
5.2.1 Strip footings 135
5.2.2 Pad footings 135
5.2.3 Combined footings 136
5.2.4 Raft or mat foundations 136
5.3 Bearing capacity 136
5.3.1 Uniform soils 138
5.3.1.1 General formulae 143
5.3.1.2 Soil layers of finite depth 147
5.3.2 Non-uniform soils 148
5.3.2.1 Strength increasing with depth 148
5.3.2.2 Fissured clays 151
5.3.2.3 Footings on slopes 151
5.3.2.4 Layered soils 154
5.3.2.5 Working platforms 157
5.4 Numerical analysis 161
5.5 Settlement 162
5.5.1 Limits of settlement 163
5.5.2 Settlement computation 164
5.5.3 Theory of elasticity 164
5.5.4 Rate of settlement 166
5.5.5 Settlement of footings on sand 169
5.5.6 Methods based on settlement and bearing criteria 172
5.6 Numerical approaches 174
5.6.1 Layered soil: Finite layer approaches 174
Contents ix
5.6.2 Finite element methods 175
5.6.3 Estimation of soil parameters 178
5.7 Raft foundations 179
5.7.1 Strip rafts 180
5.7.2 Circular rafts 180
5.7.3 Rectangular rafts 181
5.7.4 Raft foundations of general shape 183
5.8 Reactive soils 184
5.8.1 Pad or strip footings 187
5.8.2 Rafts on reactive soils 189
5.9 Cold climates 189
Appendix 5A 190
6 Deep foundations 191
6.1 Introduction 191
6.2 Types of piles 191
6.2.1 Driven piles 192
6.2.2 Driven and precast piles 192
6.2.3 Jacked piles 192
6.2.4 Bored piles 193
6.2.5 Composite piles 193
6.2.6 Grout injected piles 195
6.3 Installation 195
6.3.1 Types of displacement piles 195
6.3.2 Small displacement piles 195
6.4 Pile driving equipment 195
6.4.1 Piling rigs 196
6.4.2 Piling winches 196
6.4.3 Piling hammers 196
6.4.4 Helmet, driving cap, dolly, and packing 199
6.5 Problems with driven piles 199
6.5.1 Problems from soil displacement 199
6.6 Non-displacement piles 200
6.6.1 Precautions in construction and inspection of bored piles 200
6.6.2 Continuous flight auger piles (or grout injected piles) 201
6.7 Design considerations 201
6.8 Selection of pile type 202
6.9 Designs of piles 202
6.10 Single piles 202
6.10.1 Piles in clay 203
6.10.2 Piles in sand 204
6.10.3 Lambda method 206
6.11 Methods based on field tests 207
6.11.1 Correlations with standard penetration test (SPT) data 207