CONTETNS Preface Introduction 1.1 Introduction 1 1 .2 Soil mechanics 2 1.3 Range of problems/applications 2 1.4 Scope of this book 10 1.5 Mind maps 11 2 Stress in soils 12 2.1 Introduction 12 2.2 Equilibrium 12 2.3 Gravity 13 2.4 Stress 16 2.5 Exercises: Stress 18 2.6 Vertical stress profile 18 2.6.1 Worked examples 21 2.7 Water in the ground: Introduction to hydrostatics 23 2.7.1 Worked example: Archimedes uplift on spherical object 26 2.8 Total and effective stresses 28 2.8.1 Worked examples 32 2.9 Summary 37 2.10 Exercises: Profiles of total stress, effective stress, pore pressure 37 3 Density 40 3.1 Introduction 40 3.2 Units 40 3.3 Descriptions of packing and density 41 3.3.1 Volumetric ratios 43 3.3.2 Water content 44 3.3.3 Densities 44 3.3.4 Unit weights 46 3.3.5 Typical values 46 3.4 Measurement of packing 47 3.4.1 Compaction 50 3.5 Soil particles 52 3.6 Laboratory exercise: particle size distribution and other classification tests 56 3.6.1 Sieving 56 3.6.2 Sedimentation 57 3.6.3 Particle shape 61 3.6.4 Sand: relative density 61 3.7 Summary 62 3.8 Exercises: Density 64 3.8.1 Multiple choice questions 64 3.8.2 Calculation exercises 65 4 Stiffness 67 4.1 Introduction 67 4.2 Linear elasticity 67 4.3 Natural and true strain 70 4.4 One-dimensional testing of soils 70 4.4.1 Hooke's Law: confined one-dimensional stiffness A 72 4.5 One-dimensional (confined) stiffness of soils 74 4.6 Calculation of strains 78 4.6.1 Worked examples: Calculation of settlement 79 4.7 Overconsolidation 82 4.7.1 Worked examples: Overconsolidation 84 4.8 Summary 87 4.9 Exercises: Stiffness 87 5 Seepage 90 5.1 Introduction 90 5.2 Total head: Bernoulli's equation 90 5.3 Poiseuille's equation 96 5.4 Permeability 99 5.4.1 Darcy or Forchheimer? 102 5.5 Measurement of permeability 104 5.6 Permeability of layered soil 106 5.7 Seepage forces 108 5.8 Radial flow to vertical drain 111 5.9 Radial flow to point drain 112 5.10 Worked examples: Seepage 113 5.10.1 Example: flow through soil column 113 5.10.2 Example: effect of changing reference datum 116 5.10.3 Example: pumping from aquifer 117 5.10.4 Example: ilow into excavation 119 5.11 Summary 121 5.12 Exercises: Seepage 123 6 Change in stress 127 6.1 Introduction 127 6.2 Stress change and soil permeability 127 6.3 Worked examples 130 6.3.1 Example 1 130 6.3.2 Example 2 131 6.3.3 Example 3 133 6.4 Summary 134 6.5 Exercises; Change in stress 136 7 Consolidation 138 7.1 Introduction 138 7.2 Describing the problem 140 7.3 Parabolic isochrones 142 7.4 Worked examples 149 7.4.1 Example 1: Determination of coefficient of consolidation 149 7.4.2 Example 2 152 7.4.3 Example 3 154 7.4.4 Example 4 155 7.5 Consolidation: exact analysis A 155 7.5.1 Semi-infinite layer 159 7.5.2 Finite layer 161 7.6 Summary 165 7.7 Exercises: Consolidation 167 8 Strength 169 8.1 Introduction 169 8.2 Failure mechanisms 169 8.3 Shear box and strength of soils 171 8.4 Strength model 173 8.5 Dilatancy 174 8.6 Drained and undrained strength 177 8.7 Clay: overconsolidation and undrained strength 179 8.8 Pile load capacity 181 8.9 Infinite slope 185 8.9.1 Laboratory exercise: Angle of repose 191 8.10 Undrained strength of clay: fall-cone test 193 8.11 Simple modt-1 of shearing A 195 8.11.1 Stiffness 196 8.1 L.2 Strength 197 8.11.3 Mobilisation of strength 197 8.11.4Dilatancy 198 8.11.5 Complete stress:strain relationship 199 8.11.6 Drained and undrained response 200 8.11.7 Model: summary 203 8.12 Summary 203 8.13 Exercises: Strength 205 9 Soil-structure interaction 208 9.1 Introduction 208 9.2 Pile under axial loading A 211 9.2.1 Examples 215 9.3 Bending of an elastic beam 4 216 9.4 Elastic beam on elastic foundation 220 9.5 Pile under lateral loading A 224 9.6 Soil-structure interaction: next steps 226 9.7 Summary 227 9.8 Exercises: Soil-structure interaction 227 10 Envoi 230 10.1 Summary 230 10.2 Beyond the single dimension 231 Exercises: numerical answers 232 Index 237