Geotechnical Engineering Design

Preface xi

About the Authors xiii

About the Companion Website xv

1. Introduction to Engineering Geology 1

1.1 Introduction 1

1.2 Structure of the Earth and geologic time 1

1.3 Formation and classification of rocks 2

1.3.1 Igneous rocks 3

1.3.2 Sedimentary rocks 3

1.3.3 Metamorphic rocks 4

1.4 Engineering properties and behaviors of rocks 4

1.4.1 Geotechnical properties of rocks 4

1.4.2 Comparison of the three types of rocks 6

1.5 Formation and classification of soils 6

1.5.1 Soils formation 6

1.5.2 Soil types 7

1.5.3 Residual and transported soils 8

1.6 Maps used in engineering geology 9

1.6.1 Topographic maps 9

1.6.2 Geologic map 9

Homework Problems 12

References 14

2. Geotechnical Subsurface Exploration 15

2.1 Framework of subsoil exploration 15

2.2 Field drilling and sampling 15

2.2.1 Information required before drilling and sampling 15

2.2.2 Drill rigs 17

2.2.3 Drilling methods and augers 17

2.2.4 Soil sampling methods 23

2.3 Geotechnical boring log 29

2.4 In situ field testing 29

2.4.1 Standard penetration test (SPT) 29

2.4.2 Cone penetration test (CPT) 34

2.4.3 Vane shear test 35

2.4.4 Flat plate dilatometer test 36

2.4.5 Inclinometer test 37

2.4.6 Groundwater monitoring well 38

2.5 Subsurface investigations using geophysical techniques 39

2.5.1 Ground penetration radar (GPR) 40

2.5.2 Electromagnetics in frequency domain and in time domain 42

2.5.3 Electrical resistivity imaging 44

2.5.4 Microgravity 45

2.5.5 Seismic refraction and seismic reflection 45

2.6 Geotechnical investigation report 48

2.6.1 Site reconnaissance and description 48

2.6.2 Subsurface exploration (field exploration) 49

2.6.3 Laboratory testing 50

2.6.4 Geotechnical engineering recommendations 50

2.6.5 Appendix 51

Homework Problems 51

References 56

3. Shallow Foundation Design 57

3.1 Introduction to foundation design 57

3.2 Bearing capacity of shallow foundations 59

3.2.1 Failure modes of shallow foundations 60

3.2.2 Terzaghi's bearing capacity theory 61

3.2.3 The general bearing capacity theory 64

3.2.4 Effect of groundwater on ultimate bearing capacity 67

3.2.5 Foundation design approach based on allowable bearing capacity and the global factor of safety approach 69

3.2.6 Foundation design approach based on allowable bearing capacity and the partial factor of safety approach 71

3.2.7 Bearing capacity of eccentrically loaded shallow foundations 81

3.2.8 Mat foundations 90

3.3 Settlements of shallow foundations 92

3.3.1 Vertical stress increase due to external load 92

3.3.2 Elastic settlement 98

3.3.3 Consolidation settlement 103

Homework Problems 108

References 116

4. Introduction to Deep Foundation Design 118

4.1 Introduction to deep foundations 118

4.1.1 Needs for deep foundation 118

4.1.2 Foundation types 118

4.1.3 Driven pile foundation design and construction process 118

4.2 Pile load transfer mechanisms and factor of safety 120

4.3 Static bearing capacity of a single pile 123

4.3.1 Nordlund method, for cohesionless soil 123

4.3.2 a-method, for undrained cohesive soil 130

4.3.3 ß-method, for drained cohesionless and cohesive soils 134

4.3.4 Bearing capacity (resistance) on the basis of the results of static load tests 137

4.4 Vertical bearing capacity of pile groups 139

4.5 Settlement of pile groups 144

4.5.1 Elastic compression of piles 145

4.5.2 Empirical equations for pile group settlement using field penetration data 145

4.5.3 Consolidation settlement of a pile group in saturated cohesive soil 145

Homework Problems 150

References 152

5. Slope Stability Analyses and Stabilization Measures 154

5.1 Introduction 154

5.2 Overview of slope stability analyses 156

5.3 Slope stability analyses - infinite slope methods 159

5.3.1 Dry slopes 159

5.3.2 Submerged slopes with no seepage 160

5.3.3 Submerged slopes with seepage parallel to the slope face 161

5.4 Slope stability analyses - Culmann's method for planar failure surfaces 163

5.5 Slope stability analyses - curved failure surfaces 168

5.5.1 Undrained clay slope (f = 0) 168

5.5.2 c - f soil (both c and f are not zero) 171

5.6 Slope stability analyses - methods of slices 173

5.6.1 Ordinary method of slices (Fellenius method of slices) 173

5.6.2 Bishop's modified method of slices 178

5.7 Slope stability analyses - consideration of pore water pressure 181

5.7.1 Bishop-Morgenstern method 181

5.7.2 Spencer charts 189

5.7.3 Michalowski charts 193

5.8 Morgenstern charts for rapid drawdown 194

5.9 Averaging unit weights and shear strengths in stratified slopes 198

5.10 Slope stability analyses - finite element methods 199

5.11 Slope stabilization measures 200

5.11.1 Surface drainage 201

5.11.2 Internal drainage 201

5.11.3 Unloading 202

5.11.4 Buttress and berm 204

5.11.5 Slope reinforcements 204

5.11.6 Soil retaining walls 206

Homework Problems 207

References 211

6. Filtration, Drainage, Dewatering, and Erosion Control 212

6.1 Basics of saturated flow in porous media 212

6.2 Filtration methods and design 214

6.3 Dewatering and drainage 217

6.3.1 Open pumping 218

6.3.2 Well points 218

6.3.3 Deep wells 219

6.3.4 Vacuum dewatering 220

6.3.5 Electroosmosis 220

6.4 Surface erosion and control 223

6.4.1 Surface erosion on embankments and slopes 223

6.4.2 Surface erosion control measures 223

6.5 Subsurface erosion and seepage control methods 227

6.5.1 Subsurface erosion 227

6.5.2 Underseepage control methods in levees and earthen dams 228

6.5.3 Through-seepage control methods in levees and earthen dams 230

Homework Problems 234

References 236

7. Soil Retaining Structures 237

7.1 Introduction to soil retaining structures 237

7.2 Lateral earth pressures 237

7.2.1 At-rest earth pressure 239

7.2.2 Rankine's theory 242

7.2.3 Coulomb's theory 248

7.3 Conventional retaining wall design 250

7.3.1 Factor of safety against overturning 250

7.3.2 Factor of safety against sliding 253

7.3.3 Factor of safety of bearing capacity 254

7.3.4 Retaining wall drainage 256

7.4 Sheet pile wall design 262

7.4.1 Failure modes 262

7.4.2 Preliminary data for the design 263

7.4.3 Design of cantilever walls penetrating cohesionless soils 264

7.4.4 Design of cantilever walls penetrating cohesive soils 275

7.5 Soil nail wall design 280

7.5.1 Initial design parameters and conditions 283

7.5.2 Global stability failure 284

7.5.3 Sliding failure 288

7.5.4 Bearing capacity failure 291

Homework Problems 297

References 304

8. Introduction to Geosynthetics Design 305

8.1 Geosynthetics types and characteristics 305

8.2 Design of mechanically stabilized Earth walls using geosynthetics 308

8.2.1 Design procedures of geosynthetic MSE walls 310

8.3 Design of reinforced soil slopes 322

8.4 Filtration and drainage design using geotextiles 339

8.4.1 Hydraulic properties of geotextiles 339

8.4.2 Filtration and drainage criteria 340

Homework Problems 346

References 352

9. Introduction to Geotechnical Earthquake Design 353

9.1 Basic seismology and earthquake characteristics 353

9.1.1 Seismic faults and earthquake terminology 353

9.1.2 Seismic waves 353

9.1.3 Earthquake characteristics 357

9.2 Dynamic Earth pressures 361

9.2.1 Dynamic active earth pressure 361

9.2.2 Dynamic passive earth pressure 362

9.3 Seismic slope stability 367

9.3.1 Pseudostatic analysis 368

9.3.2 Newmark sliding block analysis 375

9.3.3 Makdisi-Seed analysis 377

9.4 Liquefaction analysis 379

9.4.1 Liquefaction hazard 379

9.4.2 Evaluations of liquefaction hazard 381

9.4.3 Evaluation of CSR 381

9.4.4 Evaluation of CRR 382

Homework Problems 391

References 397

Index 399