Contents
Foreword I Foreword II Preface
Chapter 1 Principles and Implementation of DEM 1
1.1 Application and Numerical Calculation Software of DEM 1
1.2 Basic Principles of DEM 4
1.2.1 Contact Model of Elements 4
1.2.2 Connection of Two Different Elements 6
1.2.3 Time Step Iterative Algorithm 6
1.3 Damping Harmonic Vibration of Elements 7
1.3.1 Damping Force of Elements 7
1.3.2 Equation of the Damping Harmonic Vibration 8
1.3.3 Relation Between Vibration Period and Element Radius 9
1.3.4 Differences of the Element Motion 9
1.3.5 Damping and Optimal Damping Coefficient 10
1.4 Energy Conversion and Energy Conservation of DEM 13
1.4.1 Mechanical Energy of Systems 13
1.4.2 Calculation of Heat 14
1.4.3 Energy Conservation and External Work 16
1.5 Calculation Scale and Engineering Application Feasibility of DEM 17
1.6 Understanding and Solution to the Three Major Issues in DEM 19
1.6.1 High-Performance Matrix Computing of the Discrete Element Method 19
1.6.2 Quantitative Modeling Problem of DEM 21
1.6.3 Multi-field Coupling Method Based on DEM 24
1.7 Development and Prospect of MatDEM 25
Chapter 2 The Basic Structure of MatDEM 28
2.1 The Software Foundation 28
2.1.1 The Operating Environment and Software Installation 28
2.1.2 The Windows Program for MatDEM 30
2.1.3 Operation and Termination of the Software 34
2.1.4 A Brief Introduction to the Application of the Software 35
2.1.5 A Brief Introduction to the Help File 38
2.2 The Program Structure of MatDEM 39
2.2.1 The Software Folders of MatDEM 39
2.2.2 The Hierarchical Structure of MatDEM 39
2.2.3 The Main Classes in MatDEM 41
2.3 Types of Element in MatDEM 44
2.3.1 Active Element�� Wall Element�� and Virtual Element 44
2.3.2 Fix the Degree of Freedom of Elements 45
2.3.3 The Rule of Numbering Elements 46
2.4 The Data Structure of MatDEM 46
2.4.1 The Property Arrays of Elements 46
2.4.2 The Neighbor Matrix and Connection Information Matrix 47
2.4.3 The Data Structure and Operation of Groups 50
2.5 The Contact Model Between Elements 53
2.5.1 The Linear Elastic Contact Model 53
2.5.2 The Hertz Contact Model 53
2.6 The Elastic Clump 55
2.6.1 The Principle of the Elastic Clump 55
2.6.2 Usage of the Elastic Clump 57
Chapter 3 Geometric Modeling and Material Setup 60
3.1 Building a Numerical Simulation Box 60
3.1.1 Building a Packing Model 60
3.1.2 Creating an Empty Box 64
3.2 The Foundation of Modular Modeling 65
3.2.1 Modeling with a Structure 65
3.2.2 Element Filtering 71
3.2.3 Tool_Cut and Digital Elevation Model 73
3.3 Modeling Based on Digital Images 75
3.3.1 Importing a Binary Image to Cut a Model 75
4.5.1 Compression of Files 120
4.5.2 Saving and Reading of Files 121
Chapter5 Post-processing and System Functions 123
5.1 Post-processing Window Interface 123
5.1.1 Main Post-processing Window 123
5.1.2 Saving the Post-processing Figure 125
5.1.3 Making GIF Window 127
5.2 Post-processing Drawing Functions 129
5.2.1 General Drawing Function d.show 129
5.2.2 Slice Display and Filter Display 135
5.2.3 Element Position and Force Display 137
5.3 Data Processing and Curve Drawing 138
5.3.1 Drawing Curves with Saved Data 138
5.3.2 Drawing Curves with MatDEM Automatically Recorded Data 139
5.3.3 Processing Data and Plotting in MATLAB 141
5.4 System Functions 143
5.4.1 GPU Computing Settings and Status Viewing 143
5.4.2 Definition and Operation of Functions 145
5.4.3 Batch Processing of Code Files 146
5.4.4 Random Seed and Stochastic Model 147
5.4.5 Timing Functions 147
5.5 Modeling with System Underlying Functions 148
5.5.1 Underlying Modeling of the Two-Ball Collision Process 148
5.5.2 Use Graphs to Analyze Collision Processes 151
Chapter 6 Basic Application of Geotechnical Engineering 153
6.1 Pile-soil Interaction 153
6.1.1 Packing Model of Particles 153
6.1.2 Build a Pile-Soil Interaction Model 156
6.1.3 Numerical Simulation of the Pile Pulling Process 161
6.2 Tunnel Modeling 164
6.2.1 Packing Model of Particles 165
6.2.2 Build a Tunnel Model 165
6.2.3 Loading and Numerical Simulation 170
6.3 TBM Cutter Rock Breaking 173
6.3.1 Packing Model of Particles 173
6.3.2 Build a Model of TBM Cutter Rock Breaking 174
6.3.3 Numerical Simulation Process of Rock Breaking with Hob 178
6.3.4 Improve the Calculation Speed of Rock Breaking with Hob 181
Chapter 7 Rock-Soil Body Discrete Element Tests 183
7.1 Direct Shear and Torsional Shear Tests 183
7.1.1 Define Test Parameter and Accumulate Sample 184
7.1.2 Making a Shear Box and Cutting Sample 185
7.1.3 Putting the Sample into the Shear Box 191
7.1.4 Material Setting and Numerical Simulation 193
7.2 True Triaxial Test and Joint Modeling 197
7.2.1 Build a True Triaxial Test Chamber 197
7.2.2 Defining Fracture Surface Using Tria