Geotechnical Modelling Book

	Preface	ix
1	Introduction to modelling	1
1.1	Introduction	1
1.2	Empirical models	1
1.2.1	Vane strength correction	2
1.2.2	Consolidation settlement	4
1.2.3	Cone penetration test and settlement of footings on sand	8
1.2.4	Pressuremeter	11
1.3	Theoretical models	14
1.3.1	Steady seepage	14
1.4	Numerical modelling	17
1.5	Constitutive modelling	18
1.6	Physical models	20
1.6.1	Physical models: full-scale	21
1.6.2	Physical models: small-scale	24
1.7	Geological model	26
1.8	Classification model	28
1.9	Conclusion	32
2	Characteristics of soil behaviour	35
2.1	Introduction	35
2.2	Particle-continuum duality	36
2.3	Laboratory element testing	44
2.4	Stress and strain variables	50
2.5	Stiffness	61
2.5.1	Nonlinearity: secant and tangent stiffness	61
2.5.2	Stiffness and strain measurement	67
2.5.3	Stiffness and history: stress response envelopes	69
2.5.4	Anisotropy of stiffness	75
2.6	Dilatancy	82
2.6.1	Critical states: state variable	86
2.6.2	Pore pressure parameter	88
2.7	Strength	89
3	Constitutive modelling	97
3.1	Introduction	97
3.2	Elastic models	98
3.2.1	Conventional drained triaxial compression test	103
3.2.2	Conventional undrained triaxial compression test	103
3.2.3	Measurement of elastic parameters with different devices	105
3.2.4	Anisotropy	107
3.2.5	Nonlinearity	112
3.2.6	Heterogeneity	116
3.3	Elastic-perfectly plastic models	117
3.3.1	General elastic-perfectly plastic model	119
3.3.2	A digression: collapse of portal frame	120
3.3.3	General elastic-perfectly plastic model (continued)	123
3.3.4	Elastic-perfectly plastic Mohr-Coulomb model	124
3.4	Elastic-hardening plastic models	133
3.4.1	Extended Mohr-Coulomb model	137
3.4.2	Cam clay	153
3.5	Modelling non-monotonic loading	166
3.6	Modelling cementation and structure	168
3.7	Modelling rate effects	169
3.8	Design of programmes of laboratory tests	172
3.9	Selection of soil parameters: calibration of models	178
4	Numerical modelling	181
4.1	Introduction	181
4.2	Field problems	182
4.2.1	One-dimensional problem	182
4.2.2	Two-dimensional problem	185
4.3	One-dimensional finite elements	187
4.4	Two-dimensional finite elements	190
4.4.1	Example: Constant strain triangle	192
4.4.2	Example: Linear strain triangle	193
4.4.3	Quadrilateral elements	195
4.4.4	Comparison of elements	197
4.5	Integration--Gauss points	199
4.5.1	Reduced integration	200
4.6	Nodal forces and external loads	202
4.7	Dynamic analysis	204
4.8	Finite differences	206
4.9	Solution schemes	211
4.10	Conduct of numerical modelling	217
4.10.1	Verification: Is the program doing what it claims to be doing?	218
4.10.2	Are we getting the answers that we think we are getting?	220
4.10.3	Validation: Are we getting the answers that we need?	222
4.10.4	Exercise in numerical modelling: FLAC analysis of footing on Mohr-Coulomb soil	225
4.11	Closure	231
5	Physical modelling	233
5.1	Introduction	233
5.2	Dimensional analysis	234
5.2.1	Slope in cohesive soil	234
5.2.2	Fall-cone	237
5.2.3	Consolidation	237
5.2.4	Fluid drag	238
5.2.5	Settlement of a footing	240
5.2.6	Bearing capacity of a footing	243
5.2.7	Soil nonlinearity	245
5.3	Scaling laws revisited	246
5.3.1	Length	248
5.3.2	Density	248
5.3.3	Acceleration	249
5.3.4	Stiffness	250
5.3.5	Strain	251
5.3.6	Displacement	252
5.3.7	Permeability	253
5.3.8	Hydraulic gradient	254
5.3.9	Time scales	255
5.3.10	Shear wave velocity	257
5.4	Soil-structure interaction	258
5.4.1	Footing	258
5.4.2	Pile under lateral loading	259
5.4.3	Flexible retaining wall	262
5.4.4	Buried flexible culvert	263
5.4.5	Piles under axial load	265
5.4.6	Dynamic soil-structure interaction	266
5.5	Single gravity modelling	267
6	Centrifuge modelling	269
6.1	Introduction	269
6.2	Mechanics of centrifuge modelling	269
6.3	Centrifuges	274
6.4	Model preparation	281
6.5	Geotechnical processes	284
6.6	Pore fluid	294
6.7	Site investigation	296
6.8	Instrumentation	299
6.9	Modelling and testing	304
6.10	Closure	307
7	Theoretical modelling	309
7.1	Introduction	309
7.2	Elastic stress distributions	310
7.3	Plastic failure analysis	314
7.3.1	Bound theorems	315
7.3.2	Structural example	315
7.3.3	Continuum problems--Mohr's circle	318
7.3.4	Bearing capacity of cohesive soil	319
7.3.5	Wall retaining cohesive soil	331
7.3.6	Bearing capacity of frictional soil	334
7.4	One-dimensional consolidation	344
7.4.1	Parabolic isochrones	349
7.4.2	General power law approximate solution	351
7.4.3	Pore pressures for stability analysis of embankment on soft clay	352
7.5	Macroelement models	360
7.5.1	Box model	360
7.5.2	Wall model	371
7.5.3	Footing model	375
7.5.4	Extended Newmark sliding block model	381
7.6	Closure	385
8	Soil-structure interaction	387
8.1	Introduction	387
8.2	Elastic analyses	387
8.2.1	Beam on elastic foundation	387
8.2.2	Pile under lateral loading	393
8.2.3	Pile under axial loading	394
8.2.4	Piled raft	399
8.3	Serviceability calculations	404
8.4	Relative foundation stiffness	409
8.5	Downdrag on pile	412
8.6	Settlement reducing piles	417
8.7	Flexible retaining wall	421
8.8	Tunnel lining	429
8.9	Pile in displacing ground	435
8.10	Integral bridge abutment	445
8.11	Closure	458
9	Envoi	459
	Bibliography	463
	Index	477