Modelling of Soil Behaviour with Hypoplasticity: Another Approach to Soil Constitutive Modelling (Springer Series in Geomechanics and Geoengineering)

This book explains the hypoplastic modelling framework. It is divided into two parts, the first of which is devoted to principles of hypoplasticity. First, the basic features of soil’s mechanical behaviour are introduced, namely non-linearity and asymptotic properties. These features are then incorporated into simple one-dimensional hypoplastic equations for compression and shear. Subsequently, a hypoplastic equivalent of the Modified Cam-Clay model is developed in 2D space using stress and strain invariants to demonstrate key similarities and differences between elasto-plastic and hypoplastic formulations. Lastly, the mathematical structure of hypoplastic models is explained by tracing their historical development, from the early trial-and-error models to more recent approaches. In turn, Part II introduces specific hypoplastic models for soils. First, two reference models for sand and clay are defined. After summarising their mathematical formulations, calibration procedures are described and discussed. Subsequently, more advanced modelling approaches are covered: the intergranular strain concept incorporating the effects of small strain stiffness and cyclic loading, viscohypoplasticity for predicting rate effects, soil structure to represent structured and bonded materials and soil anisotropy. The book concludes with a description of partial saturation and thermal effects: topics that are increasingly important to the disciplines of energy and environmental geotechnics. Selecting a constitutive model and its parameters is often the most important and yet challenging part of any numerical analysis in geotechnical engineering. Hypoplasticity involves a specific class of soil constitutive models, which are described in detail here. The book offers an essential resource, both for model users who need a more advanced model for their geotechnical calculations and are mainly interested in parameter calibration procedures, and for model developers who are seeking a comprehensive understanding of the mathematical structure of hypoplasticity. Preface 7 Acknowledgements 9 Contents 10 Part I Fundamentals 13 1 Introduction 14 1.1 Notation and Conventions 14 1.2 Constitutive Models 16 1.3 Graphical Representation of Tangential Stiffness: Response Envelopes 17 1.4 Constitutive Model Classification 18 1.4.1 Elasticity 18 1.4.2 Elasto-Plasticity 19 1.4.3 Hypoplasticity 20 References 22 2 Soil Mechanical Behaviour and Its Modelling 24 2.1 Stiffness Non-linearity 25 2.1.1 Local Measurement of Deformation 25 2.1.2 Stiffness Measurement by Shear Wave Propagation 28 2.1.3 Modelling of Stiffness Non-linearity 30 2.2 Asymptotic Behaviour of Soils 37 2.2.1 Asymptotic State Concept 38 2.2.2 Experimental Investigation of Soil Asymptotic Behaviour 40 2.2.3 Discrete Element Investigation of Soil Asymptotic Behaviour 44 2.2.4 Constitutive Modelling of Soil Asymptotic Behaviour 46 References 48 3 Simple Scalar and Vectorial Hypoplastic Models 54 3.1 Scalar Models for Shear 54 3.1.1 Elasto-Plastic Scalar Model for Shear 54 3.1.2 Hypoplastic Scalar Model for Shear 57 3.1.3 Predictions of Scalar Models for Shear 57 3.1.4 Modelling Stress-Dependency of Soil Behaviour 58 3.1.5 Modelling Non-linearity in Hypoplasticity 59 3.1.6 Ratcheting in Hypoplasticity Versus Reversible Response of Elasto-Plasticity 61 3.2 Scalar Models for Compression 61 3.2.1 Elasto-Plastic Scalar Model for Compression 62 3.2.2 Hypoplastic Scalar Model for Compression 65 3.2.3 An Alternative Way of Formulating the Hypoplastic Model 67 3.2.4 Predictions of Scalar Models for Compression 69 3.3 Vectorial Models for Asymptotic Behaviour 72 3.3.1 Elasto-Plastic Critical State Model 73 3.3.2 Hypoplastic Model Predicting Asymptotic States 76 3.3.3 Predictions of Vectorial Models Incorporating Asymptotic States 80 References 83 4 Tensorial Hypoplastic Models 84 4.1 The First Hypoplastic Models Without Pyknotropy 84 4.2 Incorporation of Pyknotropy and Critical States 87 4.3 Explicit Incorporation of Failure Surface 90 4.4 Explicit Incorporation of Asymptotic States 93 References 95 Part II Hypoplastic Models for Soils 97 5 Hypoplastic Model for Sand 98 5.1 Model Formulation 98 5.2 Material Parameters and Their Calibration 99 References 110 6 Hypoplastic Model for Clay 111 6.1 Model Formulation 111 6.2 Material Parameters and Their Calibration 116 References 124 7 Advanced Modelling Approaches 126 7.1 Small Strain Stiffness – Intergranular Strains 126 7.1.1 Intergranular Strains in 1D 127 7.1.2 Intergranular Strains in 2D 128 7.1.3 Tensorial Formulation of the Intergranular Strain Concept 130 7.1.4 Modifications of the Intergranular Strain Concept 132 7.1.5 Calibration of the Intergranular Strain Concept Parameters 134 7.2 Rate Effects - Viscohypoplasticity 139 7.2.1 Model Formulation 140 7.2.2 Viscohypoplasticity with Explicitly Defined Asymptotic States 145 7.2.3 Calibration of the Rate Effects-Related Parameters 146 7.3 Clay Structure 150 7.3.1 Mechanical Behaviour of Structured Clays 150 7.3.2 Hypoplastic Modelling of Structured Clays 152 7.3.3 Calibration of Material Parameters – Clays with a Stable Structure 155 7.3.4 Calibration of Material Parameters – Clays with a Meta-Stable Structure 156 7.3.5 Examples of Model Predictions 158 7.4 Very Small Strain Stiffness Anisotropy 160 7.4.1 Formulation of the Clay Hypoplastic Model with Small Strain Stiffness Anisotropy 161 7.4.2 Model Parameters and Their Calibration 163 7.4.3 Model Evaluation Using Hollow Cylinder Experimental Data 166 7.5 Partial Saturation 168 7.5.1 Stress State Description 169 7.5.2 Dependency of Asymptotic States on Suction 171 7.5.3 Water Retention Behaviour 174 7.5.4 Coupled Hydro-Mechanical Modelling of Partially Saturated Soils 179 7.5.5 Parameters of the Coupled Hydro-Mechanical Model for Partially Saturated Soils 181 7.5.6 Examples of the Model Predictions 183 7.6 Thermal Effects 183 7.6.1 Influence of Temperature on Soil Mechanical Behaviour 184 7.6.2 Thermomechanical Hypoplastic Model for Saturated Soils 186 7.6.3 Thermomechanical Model for Partially Saturated Soils 187 7.6.4 Model Parameters and Their Calibration 188 7.6.5 Demonstration of the Model Predictions 189 References 191 8 Concluding Remarks 197 "This book explains the hypoplastic modelling framework. It is divided into two parts, the first of which is devoted to principles of hypoplasticity. First, the basic features of soil's mechanical behaviour are introduced, namely non-linearity and asymptotic properties. These features are then incorporated into simple one-dimensional hypoplastic equations for compression and shear. Subsequently, a hypoplastic equivalent of the Modified Cam-Clay model is developed in 2D space using stress and strain invariants to demonstrate key similarities and differences between elasto-plastic and hypoplastic formulations. Lastly, the mathematical structure of hypoplastic models is explained by tracing their historical development, from the early trial-and-error models to more recent approaches. In turn, Part II introduces specific hypoplastic models for soils. First, two reference models for sand and clay are defined. After summarising their mathematical formulations, calibration procedures are described and discussed. Subsequently, more advanced modelling approaches are covered: the intergranular strain concept incorporating the effects of small strain stiffness and cyclic loading, viscohypoplasticity for predicting rate effects, soil structure to represent structured and bonded materials and soil anisotropy. The book concludes with a description of partial saturation and thermal effects: topics that are increasingly important to the disciplines of energy and environmental geotechnics. Selecting a constitutive model and its parameters is often the most important and yet challenging part of any numerical analysis in geotechnical engineering"--Page 4 of cover Front Matter ....Pages i-xiii Front Matter ....Pages 1-1 Introduction (David Mašín)....Pages 3-12 Soil Mechanical Behaviour and Its Modelling (David Mašín)....Pages 13-42 Simple Scalar and Vectorial Hypoplastic Models (David Mašín)....Pages 43-72 Tensorial Hypoplastic Models (David Mašín)....Pages 73-85 Front Matter ....Pages 87-87 Hypoplastic Model for Sand (David Mašín)....Pages 89-101 Hypoplastic Model for Clay (David Mašín)....Pages 103-117 Advanced Modelling Approaches (David Mašín)....Pages 119-189 Concluding Remarks (David Mašín)....Pages 191-192