Stability analyses on slopes of clay-rock mixtures using discrete element method

The limit equilibrium method (LEM) and finite element method (FEM) are widely used for slope stability analyses, and usually satisfactory results can be achieved. However, the LEM and FEM may not work well for slopes comprised of clay-rock mixtures, as they feature the characteristics of both continuum and discrete media. In this study, the discrete element method (DEM) was used to analyze the stability of slopes composed of clay-rock mixtures. Since the morphology of rock blocks played an important role in the mechanical behaviors of the mixed soils, a systematic approach which could yield close approximation of rock shape was applied to the numerical model. The numerical results showed that when the rock content was less than 60%, the factor of safety (FS) for clay-rock slope was even smaller than clay slope, which indicated rock blocks were inactive and even imposed adverse influence on slope stability. Only when rock content was greater than 60%, the FS was largely enhanced by the existence of rocks. If the slope contained angular rocks with aspect ratio less than 2.0, its stability could be better sustained than the slope containing subrounded rocks or rocks with aspect ratio greater than 2.0. In the end, the FS computed from DEM analyses was compared with the FS calculated from LEM.