Study on Shear Failure and Crack Propagation Characteristics of Soil-Rock Mixture

Soil–rock mixture is a special geological material between homogeneous soil masses and fractured rock masses. In this study, the shear characteristics, movement and failure characteristics of particles and the evolution law of cracks were studied by direct shear tests and particle flow numerical simulations. The results show that the shear stress-shear displacement curves of the soil–rock mixture can be roughly classified into three stages: elastic stage, plastic stage and strain softening stage, and there was a "jump" phenomenon. The higher the rock content was, the more obvious the phenomenon. The shear strength and its indices of the soil–rock mixture did not increase with increasing rock content, but there was an "optimal rock content". According to the experimental and simulation results, particle breakage can be divided into three types: slight failure, partial failure and complete failure. The crack propagation characteristics can be divided into three stages, and the crack propagation depth increases with increasing shear displacement. It increases with increasing vertical stress and decreases with increasing block rock content.