Abstract: The analysis of joint surface damage of rock mass under dynamic loading is helpful to grasp the essential characteristics of jointed rock mass failure. In view of the current situation that few studies have been conducted on the impact of joint morphology on dynamic compression failure of jointed rock mass, we use the modified split Hopkinson pressure bar (SHPB) device to operate impact loading test on the artificial rough joint sample. Using the 3D scanner and other equipment, the damage characteristics of joint surface under multiple low-amplitude impact loads have been observed and studied quantitatively. The results show that under multiple impact loading, the amplitude of the transmitted wave is reducing, and the transmission ability of the stress wave at the joints is severely weakened. The wave velocity detection technique has been used to verify the fact that the damage of rock under multiple impact loads is reduced, whereas the damage of joint surface is more obvious. The overall undulation of rough joint surface decreases and the joint roughness increases. The morphology of joint surface including the joint matching coefficient (JMC), the joint distribution and the joint undulation are confirmed to have different influences on the joint dynamic damage effect. At the same time, we calculate the dissipated energy of joint samples using the experimental data to define the damage variables. We find that the reduction of joint matching coefficient (JMC) aggravates the damage degree of joint surface. However, by comparing the change of damage variables, the results show that there are still limitations in using the damage variables to fully describe the damage of jointed rock mass.

Key words: jointed rock mass, roughness joint, SHPB, joint surface damage, stress wave energy