Abstract

In this paper, we propose a combination of discrete elements for the soil and finite elements for the fluid flow field inside the pore space to simulate the triggering of landslides. We give the details for the implementation of third order finite elements (“P2 with bubble”) together with polygonal discrete elements, which allows the formulation with a minimal number of degrees of freedom to save computer time and memory. We verify the implementation with several standard problems from computational fluid dynamics, as well as the decay of a granular step in a fluid as test case for complex flow.

Highlights

  • We propose a combination of discrete elements for the soil and finite elements for the fluid flow field inside the pore space to simulate the triggering of landslides

  • We give the details for the implementation of third order finite elements (“P2 with bubble”) together with polygonal discrete elements, which allows the formulation with a minimal number of degrees of freedom to save computer time and memory

  • We verify the implementation with several standard problems from computational fluid dynamics, as well as the decay of a granular step in a fluid as test case for complex flow

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Summary

Micromechanics of Landslides

Landslides due to strong rain occur in rather confined areas, while the regions with the same soil and rain conditions are much larger This means there must be additional triggers. Another possible effect which loosens up dense granular matter is “Reynolds dilatancy”, where external stresses (in the case of landslides, that may be the additional weight of water due to strong rains) loosen up the soil homogeneously. A verification by direct micromechanical simulation is preferable to experiments here, as it allows much better control over the initial state and enables us to examine the exact physical processes occurring anywhere at any time within the geometry

A Combined Simulation Method of Particles and Fluids
Choice of the Discrete Element Method
Choice of the Fluid Simulation Method
Interaction between Discrete-Element Particles
FEM with Cubic Bubble
Shape Functions
Flow Equations
Iteration within a Single Timestep
Coupling between Fluids and Particles
Verification
Wall Correction Factor
Cavity Flow
Granular Step
Findings
Summary and Conclusions
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