This book reflects the latest research
results iii computer modelling of
landslide-induced debris flows. The book
establishes an understancling of the
initiation and propagation mechanisms
oflandslides by means ot'numerical
simulations， so that mitigation strategies
to reduce the long-term losses from
landslide hazards can be devised.
In this context， the book employs the
Discrete Element Method （DEM） and
Computational Fluid Dynamics（CFD）to
investigate the mechanical and hydraulic
behaviour of granular materials involved in
landslides - an aproach that yields
meaningful insights into the flow mechanisms
， concerning e.g. the mobilization of
sediments， the generation and dissipation
of excess pore water pressures， and the
evolution of effective stresses. As such，
the book provides valuable intormation，
useful methods and robust numerical tools
that can be successfully applied in the
field of debris flow research.
本書為TaoZhao著的《Coupled DEM-CFD
Analyses of Landslide-Induced Debris Flows（
精）》。

1 Introduction to LandsLides
1.1 Background
1.2 Terrestrial Landslides
1.2.1 Classification and Characteristics
1.2.2 Major Research on Terrestrial Landslides
1.3 Submerged Landslides
1.3.1 Classification and Characteristics
1.3.2 Major Research on Submerged Landslides
1.4 Model Testing-Granular Column Collapse
1.5 Numerical Investigations
1.5.1 The Finite Element Method
1.5.2 The Smoothed Particle Hydrodynamics
1.5.3 The Discrete Element Method
1.5.4 The DEM-CFD Coupling Method
2 Introduction to Discrete Element Method
2.1 The Discrete Element Method
2.1.1 Particle Motion
2.1.2 The Particle-Particle Contact Model
2.1.3 The Calculation of Stress in the DEM
2.1.4 Coordination Number
2.2 Model Validation
2.2.1 Input Parameters of the DEM Model
2.2.2 Determination of Numerical Time Step
2.2.3 Numerical Simulation of Triaxial Tests
2.2.4 Material Angle of Repose
2.3 Conclusions
3 Investigation of Dry Granular Flows
3.1 The Granular Column Collapse Model
3.2 Dimensional Analysis
3.3 Numerical Simulations
3.3.1 Deformation of the Granular Assembly
3.3.2 Influence of Initial Column Aspect Ratio
3.3.3 Influence of Model Size Ratio
3.3.4 Influence of Column Characteristic Strain
3.3.5 Infiuence of Material Internal Friction Anglr
3.4 Mechanical Analyses
3.4.1 Evolution of Granular Velocity
3.4.2 Granular Energy
3.4.3 Linear Momentum
3.4.4 Flux of Kinetic Energy
3.4.5 Distribution of Kinetic Energy and Linear Momentum
3.4.6 Evolution of Force Chains
3.4.7 Distribution of Stress
3.4.8 Distribution of Coordination Number
3.4.9 Destination of Surface Grains
3.4.10 Influence of Air Viscous Force
3.5 Conclusions
4 Introduction to the DEM-CFD Coupling Model
4.1 Fluid-Solid Interaction
4.2 Governing Equations of Fluid Flow
4.2.1 Fluid Mass Conservation Law
4.2.2 Fluid Momentum Conservation Law
4.3 The Viscous Shear Stress
4.3.1 Laminar Flow Regime
4.3.2 Turbulent Flow Regime
4.3.3 Near-Wall Treatment
4.3.4 Initial Conditions
4.4 The MPI Implementation and Data Exchange
4.5 Fluid Flow Through a Porous Soil Sample
4.5.1 Analytical Solution of Soil Permeability
4.5.2 Numerical Model Configuration
4.5.3 Laminar Flow
4.5.4 Turbulent Flow
4.6 Numerical lnvestigation of Granular Sedimentation
4.6.1 The Settling of a Single Particle
4.6.2 Batch Granular Sedimentation
4.7 Conclusions
5 Investigation of Submerged Debris Flows
5.1 Model Configuration
5.2 Physical Properties of Sediments
5.3 Dimensional Analysis
5.3.1 Discussion of the Dimensionless Groups
5.3.2 Summary of the Dimensionless Groups
5.4 Modelling of Small-Scale Submerged Debris Flows
5.4.1 Deformation of the Granular Assembly
5.4.2 Influence of Initial Column Aspect Ratio
5.4.3 Influence of Model Size Ratio
5.4.4 Influence of Characteristic Strain and Reynolds Number
5.4.5 Influence of Material Internal Friction Angle
5.5 Mechanical and Hydrodynamic Analyses
5.5.1 Evolution of Particle Velocity Field
5.5.2 Fluid Velocity Field
5.5.3 Relative Velocity, Between Particle and Water
5.5.4 Distribution of Excess Pore Water Pressure
5.5.5 Evolution of Force Chains
5.5.6 Distribution of Effective Stress
5.5.7 Distribution of Bulk Coordination Number
5.5.8 Evolution of the Run-out Distance and Deposit Height
5.6 Modelling of Large-Scale Landslides
5.6.1 Determination of Numerical Time Step
5.6.2 The Mobility of Large-Scale Submerged Landslides
5.6.3 Mechanical and Hydraulic Behaviour of Loose Sample
5.6.4 Mechanical and Hydraulic Behaviour of Dense Sample
5.7 Conclusions
6 Conclusions and Recommendations for Future Work
6.1 Summary and Conclusions
6.2 Recommendations for Future Work
Appendix A: Summary of the Selected Landslides
Appendix B: Calculation of Porosity
Appendix C: Input Parameters for Simulations
References