A novel and simple DEM simulation of unsaturated sand under fully undrained and compressible fluid condition

Abstract

This paper presents a new and simple method to investigate the unsaturated sand with a compressible fluid under undrained condition via the Distinct Element Method (DEM). In contrast to distinct element method and computational fluid dynamic approach (CFD-DEM) coupling, the pore pressure in this method is treated as the difference value between the initial confining pressure and the effective stress of the soil skeleton according to the effective stress principle. Furthermore, a compression coefficient is introduced to take into account the fluid compression, by which the changes of pore pressure and vertical strain rate of fluid can be calculated to control the movement of vertical walls. A series of three-dimensional (3D) cyclic simple shear tests were simulated to study the influence of fluid compressibility on the mechanical properties of soil. The DEM results were compared with the experimental data to verify the feasibility of the method.