Experimental and Numerical Simulation Study on the Shear Behavior of Rock-like Specimens with Non-Persistent Joints

Shear failure of non-persistent joints represents a significant contributing factor to rock mass instability. Since non-persistent joints have various parameter characteristics, it is of great practical importance to explore shear behavior with different parameters for preventing geological disasters and engineering construction. In this study, the effects of joint aperture, joint persistency, and normal stress on the shear behavior of non-persistent persistent joints were investigated by combining indoor tests with numerical simulations. Firstly, an indoor direct shear test was carried out to examine the shear stress, normal displacement, and failure patterns from a macroscopic perspective. Then, a numerical model was constructed using the FEM-CZM method to analyze the stress evolution process of non-persistent joint shear failure from a microscopic perspective. The results show that within the scope of the research, the peak shear strength of non-persistent joints is negatively correlated with joint aperture and joint persistency and positively correlated with normal stress. The residual shear strength is negatively correlated with joint persistency and positively correlated with normal stress. Peak normal displacement is negatively correlated with joint aperture and normal stress, and final normal displacement is negatively correlated with joint persistency and normal stress. The failure pattern of non-persistent joints is affected by internal stress. As joint aperture, joint persistency, and normal stress increase, stress concentration at the rock bridge intensifies, the width of the shear failure zone diminishes, and the specimen changes from tensile failure or mixed failure to shear failure. The research results may enrich the understanding of the shear behavior of non-persistent joints and provide some reference value for safe construction and geological hazard protection.