Simplifying the physico-chemical contacts in cohesive soils for efficient DEM simulations

Abstract

The aim of this study is to simplify the incorporation of the physico-chemical forces between clay particles in discrete element method (DEM) simulations to reduce the computational costs associated with such simulations. Clays have been studied in DEM frameworks utilizing contact models that incorporate the physico-chemical forces (i.e., double layer repulsive and van der Waals attractive forces) between the particles. Due to the high computational costs associated with modelling these forces, simulations were limited to a few number of clay particles which constrained the practicality of these models. In this study, the nonlinear physico-chemical forces are replaced with linear forces, and systematic procedures for deriving the repulsive and attractive stiffnesses resulting in equivalent net interparticle force are outlined. The proposed contact model cuts the running time, mainly by eliminating the timely-consuming calculation of the double layer repulsive force. First, the computational efficiency of the proposed simplification procedure is evaluated through 3-D simulations of 1-D consolidation experiments on a kaolinite clay. Then, the drained shearing response of a normally consolidated clay specimen is investigated, and the impact of the initial specimen fabric is discussed. Finally, recommendation is provided for the minimum number of DEM simulations required to ensure statistical significance of the expected behavior.