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Bifurcations, Instabilities, Degradation in Geomechanics

:	George E. Exadaktylos, Ioannis G. Vardoulakis
:	George Exadaktylos, Ioannis G. Vardoulakis
:	Bifurcations, Instabilities, Degradation in Geomechanics
:	Springer-Verlag
:	9783540493426
:	1
:	CHF 190.80
:

:	Geowissenschaften
:	English

:	469
:	Wasserzeichen/DRM
:	PC/MAC/eReader/Tablet
:	PDF

This is an up-to-date review of developments in the field of bifurcations and instabilities in geomechanics from some of the world's leading experts. Leading international researchers and practitioners of the topics debate the developments and applications which have occurred over the last few decades. Beside fundamental research findings, applications in geotechnical, petroleum, mining, and bulk materials engineering are emphasised.

	Preface	5
	Organization of the 7th International Workshop	7
	Contents	8
	Introduction	16
	1 The Concept of Bifurcation in Geomechanics	17
	Experimental Aspects	28
	Third Invariant Dependent Single Yield Surface Model and Localization Conditions for High Porosity Sandstone	29
	Summary	29
	1 Introduction	30
	2 Constitutive Relation Relation Relation Relation Relation Relation Relation Relation Relation	33
	3 Localization Conditions Conditions	38
	4 Results	42
	5 Summary and Conclusions	55
	Appendix A	58
	Interpretation of the Scale Effect in Perforation Failure	64
	Summary	64
	1 Introduction	64
	2 Mathematical Model	67
	3 Model Calibration	72
	4 Results and Discussion	74
	5 Conclusions	80
	Experimental Investigation of Instabilities of Granular Materials in Relation to Dilatancy and Fabric Issues	82
	Summary	82
	1 Introduction	83
	2 Proportional Strain Paths Paths	84
	3 Biaxial Testing Apparatus	85
	4 Proportional Strain Path Testing	87
	5 Stress (Strain) Response Envelopes and Anisotropy	96
	6 Conclusions	102
	Compactive Cataclastic Flow in Tuffeau de Maastricht Calcarenite: Mechanical Deformation	102
	105	102
	Summary	105
	1 Introduction	106
	2 Experimental Procedure and Mechanical Data	108
	3 Infinitesimal Deformation Theory of Bifurcation of Elastopla-stic Solids – Calibration of the Lade and Kim’s Model	113
	4 Back Test Analysis	126
	5 Permeability Reduction Reduction	129
	6 Concluding Remarks	133
	Local Second Gradient Models and Damage Mechanics: 1D Post-Localization Studies in Concrete Specimens	137
	1 Introduction	137
	2 Scalar Damage Model	138
	3 Local Second Gradient Model	140
	4 1D Numerical Simulations	143
	5 Expansion of the Plastic Region	147
	6 Conclusions	149
	Micromechanical Aspects	153
	Entropy and Material Instability in the Quasi-Static Mechanics of Granular Media	154
	Summary	154
	1 Statistics of Kinematics and Stress	154
	2 Maximum Entropy	154
	157	154
	3 Material Instability Instability	160
	4 Conclusions	161
	A DEM Study of Compaction Band Formation	163
	Summary	163
	1 Introduction	164
	2 The Discrete Element Method	165
	3 Results	169
	4 Proposed Statistical Approach	174
	5 Conclusions	178
	Shear Zone Formation in 2D Random Granular Specimens within Enhanced Hypoplasticity	180
	Summary	180
	1 Introduction	180
	2 Hypoplasticity	182
	3 Micro-Polar Hypoplastic Law	185
	4 Non-Local Hypoplastic Law	188
	5 Second-Gradient Hypoplastic Law	188
	6 FE-Input Data	190
	7 FE-Results	195
	8 Conclusions	201
	A Rational Approach to Stress-Dilatancy Modelling Using an Explicit Micromechanical Formulation	207
	Summary	207
	1 Introduction	208
	2 Rowe’s Stress-Dilatancy Formulation Revisited	210
	3 Effect of Fabric on Stress-Dilatancy Relations	212
	4 Stress-Dilatancy Formulation with Micromechanical Considerations	219
	5 Verification	224
	6 Simplified Procedure and Modified Rowe’s Stress-Dilatancy Relation	225
	7 Closing Remarks	233
	Micro-Fracture Instabilities in Granular Solids	237
	Summary	237
	1 Introduction	237
	2 RVE Problem Problem	238
	3 Macroscopic Loss of Ellipticity	242
	4 Numerical Examples and Discussion	243
	Constitutive Aspects	249
	Entropy and Material Instability in the Quasi-Static Mechanics of Granular Media	250
	Summary	250
	1 Statistics of Kinematics and Stress	251
	2 Single Crack Mechanics	253
	3 Representative Volume Elements Damaged by many Interacting Microcracks	260
	4 Effective