Simulation investigation of mechanical and failure characteristics of jointed rock with different shapes of joint asperities under compression loading

With the increase in the number of rock engineering projects, it has been recognized that the influence of joints on compressive damage of rock mass cannot be ignored. The existence of joints in the rock mass having complex surface configurations significantly influences its damage properties. Hence, a particle flow code (PFC2D) was used to investigate the effects of joint surface configuration on mechanical properties of jointed rock when compressed. In this study, a hybrid model with parallel bond model (PBM) and flat-joint model (FJM) was applied to simulate granite material and the complex surface configuration was simplified into four types of shapes (i.e., rectangle, trapezoid, ellipse and triangle). The shape effect on deformation and failure modes of jointed rock was discussed. The numerical results show that joint asperity diminished mechanical property of jointed rock and is prone to damage. It is reflected that strength and elastic modulus markedly decreased and asperity degradation. In addition, because of the asperity asynchronous degradation, the joint surface exhibited inconsistent displacement. The joint asperity shape affected the failure properties of jointed rock. Three failure modes of the joint asperities were observed. Finally, the shape feature of the asperities (angle, radius ratios and side length) on the deformation and degradation of joint asperity was discussed.