Practice of Discrete Element Method in Soil-Structure Interface Modelling

Foreword
Preface
Acknowledgements
About This Book
Contents
About the Authors
1 Overview of Experimental Granular Soil–Structure Interface Behavior
	1.1 Introduction
	1.2 Experimental Devices and Improvements
		1.2.1 Conventional Laboratory Test Devices
		1.2.2 Device Improvements
	1.3 Effect of Soil Properties
	1.4 Effect of Structure Properties
	1.5 Other Influence Factors
	1.6 Conclusions
	References
2 Shear Banding in 2D Numerical Interface Tests
	2.1 Introduction
	2.2 2D Interface Shear Test
		2.2.1 Numerical Modelling and Test Protocol
		2.2.2 Interface Shear Tests
	2.3 Velocity Field and Its Gradient
		2.3.1 Analyzing the Velocity Field
		2.3.2 Strain Rate Field
	2.4 Formation of Shear Band
		2.4.1 Evolution of Shear Velocity Field
		2.4.2 Development of Strain Localization
		2.4.3 Evolution of Shear Velocity Gradient
		2.4.4 Particle Rotation
	2.5 Discussion
		2.5.1 Dense Specimen S1
		2.5.2 Loose Specimen S2
		2.5.3 Volumetric Evolution Versus Strain Localization
		2.5.4 Patterns Transition Between Dense and Loose Specimens
		2.5.5 Shear Strength Versus Strain Localization
	2.6 Conclusions
	References
3 Fabric Evolution at the Soil–Structure Interface
	3.1 Introduction
	3.2 2D Interface Shear Test
		3.2.1 Numerical Modeling and Test Protocol
		3.2.2 Interface Shear Tests and Results
		3.2.3 Model Validation
	3.3 Strain Localization and Associated Void Ratio
		3.3.1 Measuring the Scale of the Localized Zone
		3.3.2 Sliding on the Interface
		3.3.3 Void Ratio e
	3.4 Microscale Properties
		3.4.1 Soil Fabric
		3.4.2 Internal Force Anisotropy
		3.4.3 Critical State and Its Micromechanical Basis in the SSI
	3.5 Conclusions
	References
4 Soil-Structure Interface Under Constant Normal Stiffness
	4.1 Introduction
	4.2 DEM Simulation
		4.2.1 Sample Preparation and Soil Properties
		4.2.2 Development of Constant Stiffness Control of Interface Shearing
	4.3 Results and Discussion of Interface Tests
		4.3.1 Macroscopic Behaviors
		4.3.2 Thickness of the Shear and Dilation Zones
		4.3.3 Void Ratio
		4.3.4 Coordination Number
		4.3.5 Force Chain and Soil Fabric
	4.4 Discussions
		4.4.1 Effect of Surface Roughness
		4.4.2 Effect of Inter-Particle Friction Coefficient
		4.4.3 2D Versus 3D Simulations
	4.5 Conclusions
	References
5 Three-Dimensional Analysis of Soil-Structural Interface
	5.1 Introduction
	5.2 DEM Simulation
		5.2.1 Model of the Interface Shear Test
		5.2.2 Interaction Law
		5.2.3 Simulation Process and Measurement
	5.3 Determining the Dimension of the Shear Box
	5.4 DEM Modeling Results and Discussion
		5.4.1 Macro-Mechanical Behavior of the Interface
		5.4.2 Localized Band Analysis
		5.4.3 Local Average Stress Analysis
		5.4.4 Material Fabric Analysis
	5.5 Conclusions
	References
6 Influences of Particle Sphericity and Fabric on the Soil-Structure Interface
	6.1 Introduction
	6.2 DEM Simulation
		6.2.1 Input Parameters
		6.2.2 Geometries of the Clumps
		6.2.3 Specimen Generation Process
		6.2.4 The Simulation of Soil-Rough Interface Shearing
	6.3 Compactness of the Specimen
	6.4 Effect of Particle Shape and Interface Roughness
		6.4.1 Macroscopic Response
		6.4.2 Interface Friction Angle Analysis
		6.4.3 Localized Band Analysis
		6.4.4 Local Porosity and Coordination Number
		6.4.5 Material Fabric Analysis
	6.5 Effect of Initial Fabric
		6.5.1 Macroscopic Response
		6.5.2 Localized Band Analysis
		6.5.3 Local Coordination Number
		6.5.4 Material Fabric Analysis
	6.6 Conclusions
	References
7 Multi-directional Soil-Structure Interface Shearing
	7.1 Introduction
	7.2 Numerical Modelling
		7.2.1 Model of Interface Direct Shear Test
		7.2.2 Simulation Process and Calibration of Input Parameters
	7.3 3D DEM Modelling Results
		7.3.1 Average Shear Stresses in Two Directions
		7.3.2 Consistent Macroscale Response of True Shear Behavior
		7.3.3 Localized Band Thickness and Particle Displacement Vector
		7.3.4 Porosity and Coordination Number
		7.3.5 Material Fabric
	7.4 Conclusions
	References
8 Interface Shear Strength Considering Structural Surface Morphology
	8.1 Introduction
	8.2 Random Surface and Morphology Parameters
	8.3 Numerical Simulation of Interface Shear Test
		8.3.1 2D DEM Simulation Limitations
		8.3.2 Numerical Model and Model Process
		8.3.3 Numerical Test Schemes
		8.3.4 Typical Interface Shearing Behavior
	8.4 Results and Discussion
		8.4.1 Analysis of Correlation by Means of Spearman’s Rank Correlation Coefficient
		8.4.2 Data Description and Model Selection
		8.4.3 Optimal Model Validation
		8.4.4 Predicted Formula Development and Comparison with Existing Predicted Formulas
	8.5 Conclusions
	References
9 Analysis of Smooth Geomembrane–Sand Interface
	9.1 Introduction
	9.2 Coupled Finite Difference–Discrete Element Framework
		9.2.1 Discrete and Continuum Simulation
		9.2.2 Contact Between Particles and Elements
		9.2.3 Coupling Simulation Mechanism
	9.3 Coupled Interface Shear Test Model
		9.3.1 Interface Shear Test Model
		9.3.2 Simulation Process
		9.3.3 Validation of the Numerical Model
	9.4 Microanalysis of Smooth Geomembrane–Sand Interface
		9.4.1 Effect of Normal Stress
		9.4.2 Effect of Surface Hardness
	9.5 Conclusions
	References
Appendix A PFC Code of Creating and Cutting Wall Under the Periodic Boundary Condition
Appendix B PFC Code of Creating Specimens with Different Porosities
Appendix C PFC Code of Constant Normal Stiffness Control
Appendix D PFC Code of Creating Specimens with the Minimum and the Maximum Densities
Appendix E MATLAB Code of 3D Contact Normal Distribution Demonstration
Appendix F PFC Code of Importing a Random Surface into the Model