　　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.

内页插图

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
6 Conclusions and Recommendations for Future Work

Appendix A： Summary of the Selected Landslides
Appendix B： Calculation of Porosity
Appendix C： Input Parameters for Simulations

References

前言/序言

　　In recent years， the increasing impacts of landslide hazards on human lives and life-line facilities worldwide has advanced the necessity to find out both economically acceptable and useful techniques to predict the occurrence and destructive power of landslides. Though many projects exist to attain this goal， the current investigation set out to establish an understanding of the initiation and propagation mechanisms oflandslides via numerical simulations， so that mitigation strategies to reduce the long-term losses from landslide hazards can be made.
　　This book summarizes some of the recent researches on landslides via the Discrete Element Method （DEM） and Computational Fluid Dynanucs （CFD）. These two methods have been used to investigate the mechanical and hydraulic behaviour of granular materials involved in landslides. The main challenge is to provide rational analyses of large-scale landslides via small-scale numerical simulations. To solve this problem， dimensional analyses have been performed on a simple granular column collapse model. The influence of governing dimensionless groups on the debris runout distance and deposit height has been studied for the terrestrial and submerged granular flows.
　　3D DEM simulations of granular flows in plane strain conditions have been performed in this research. The input parameters of the DEM model have been calibrated by the numerical triaxial tests， based on which， the relationships between the microscopic variables and the macroscopic soil strength properties were analysed. Using the simple granular column collapse model， the influences of column aspect ratio， characteristic strain， model size ratio and material internal friction angle on the runout distance and deposit height of granular materials have been examined. Additionally， the deformation and energy evolution of dry granular
　　materials are also discussed. The DEM-CFD coupling model has been employed to study the mechanical and hydraulic behaviour of highly mobilized terrestriaUsubmarine landslides. This model has been validated via numerical simulations of fluid flow through a porous soil sample and grain batch sedimentations. The simulations of granular flows in the submerged environment have led to some meaningful insights into the flow mechanisms， such as the mobilization of sediments， the generation and dissipation of excess pore water pressures and the evolution of effective stresses.
　　Overall， this study shows that the proposed numerical tools are capable of modelling the mechanical and hydraulic behaviour of terrestrial and submarine landslides.
基于流固耦合模型的泥石流运动机理分析（英文版） [Coupled DEM-CFD Analyses of Landslide-Induced Debris Flows] 下载 mobi epub pdf txt 电子书格式