DEM-FEM model of highly saturated soil motion due to seepage force

This paper examines a new approach to the problem of modeling transport phenomena that occur inside highly saturated discrete soil due to seepage force. The theory is based on a combination of the finite-element method (FEM), a solution of the poroelastic equations, and the distinct-element method (DEM) to produce a coupled numerical model. The FEM is used to calculate pore-water pressure fluctuations while the DEM is used to simulate the interactions between particles of submerged soil. This combination of different numerical schemes enables simulation of movements inside the granular material under the influence of pore-water pressure gradients. This theory and the equations used are presented and the parameters discussed. The functionality of the theory is tested in an application of the model to an embedded vertical seawall, and its accuracy is verified by a small-scale laboratory test.