Numerical Investigations on Shear Behavior and Failure Mechanism of Non-persistent Jointed Rocks

The shear behavior of the discontinuities has a significant influence on the stability of rock engineering. In this paper, the numerical and experimental direct shear tests were performed to investigate the shear behavior of non-persistent jointed rocks. Through a comprehensive calibration of shear stress-displacement curves and failure mode, good agreement was successfully achieved. Further numerical analysis was conducted to study the macro–micro failure mechanism. The results indicate that the shear failure of fractured rock mass begins at the end of crack in the rock mass where the crack initiation appears and as the crack expands inward of rock a macroscopic shear fracture zone is formed along the fracture plane finally. The rotation radian of particles appears obvious zoned phenomenon. The particles with larger rotation radian are mainly distributed at the location where the cracks occurred. The process of specimen failure is the process of unceasing redistribution of the rotation radians of particles inside the specimen. The distribution of contact force is obviously regional and directional and the distribution area of crack is always consistent with that of compressive stress concentration. The failure process of rock is the process of energy dissipation within the specimen, and the failure of the specimen is a kind of instability phenomenon driven by energy.