Discrete Element Modeling of Friction of Sand-clay Mixtures

This paper presents a preliminary study on the effect of the clay content on the mechanical properties of the fault gouge materials using the discrete element method (DEM). It is also a feasibility study to examine how numerical modeling based on the DEM can be used to predict the hydro-mechanical properties of the fault. 2-dimensional (2D) models were used. The sand and the clay particles were explicitly mimicked using mixed two groups of elements with different sizes and different mechanical properties. Simulations of biaxial compression tests were performed, and the friction coefficients of the models with different clay contents were calculated from the simulation results. The modeling results were compared with some published laboratory experimental results. They agreed qualitatively. This study therefore demonstrates that a simple 2D DEM model can qualitatively capture the effect of the clay contents on the mechanical properties of the sand-clay mixtures. However, further studies are expected to be done in order to quantitatively predict the hydro-mechanical parameters of the fault gouge materials using DEM modeling.