Transfer mechanism and criteria for static–dynamic failure of granite under true triaxial unloading test

Abstract In the construction procedure of infrastructure, excavation disturbance significantly changes initial stress state rocks in deep geotechnical engineering, and a rock burst would occur accompanied by ejection block. present study, true triaxial unloading test its corresponding numerical analysis based on three-dimensional particle flow code (PFC3D) are conducted granite specimens to acquire characteristic information static dynamic failure during explore criteria for determining failure. The results indicate that modes under can be classified into three categories: ① no obvious coalesced crack, ② main coalescence shear ③ crack with V-shaped pit. instantaneous kinetic energy is characterized sharp increase sporadic increases, while shows increase, short quiet period, substantial increase. critical combination transformation static–dynamic proposed, which consistent experimental results. number cracks gradually increases failure, it suddenly During from ratio tensile decreases. proportion bonding trend weakens. However, remains predominant granite,