Modeling shear behavior of sand-clay interfaces through two-dimensional distinct element method analysis

This study presents a numerical investigation of the shear strength and deformation behaviors of sand-clay interfaces through the distinct element method (DEM). Numerical direct shearing modeling was carried out in PFC2D (particle flow code), considering the effects of the interface geometry, stiffness ratio, friction coefficient, and soil properties. Results indicate that the interface shear strength is greatly mannered by the sample strength and loading conditions. Shear stress curves of samples with smooth interfaces, general stiffness ratio and friction coefficient feature softening behavior that experience peak strengths. The deformation is intensely localized in a narrow shear zone which is below the mid-height of samples. The sample with a sawtooth interface has lower shear strength but more coordination number. With the increase of stiffness ratio, the internal friction angle becomes smaller, and the force chain distribution becomes more uniform. Furthermore, there is an infinitesimally impact from the friction coefficient on the interface shear strength. However, the mesoscopic sliding fraction is greatly affected by the particle friction coefficient. When the bond strength is extremely large, the force chain exhibits uniform dense distribution with central symmetry along the diagonal, corresponding to more coordination number.