An SHPB Test Study on Stress Wave Energy Attenuation in Jointed Rock Masses

A series of dynamic tests were carried out to investigate the effect of joint roughness on the wave energy attenuation in rock masses and estimate the relation between joint roughness and seismic quality factor of rock masses. The modified split Hopkinson pressure bar (SHPB) apparatus was adopted in this study, where the loading, input and output bars were made of gypsum. The propagation coefficient of the gypsum bars was measured from trial tests. According to the propagation coefficient of the gypsum bars, the strain, stress and particle velocity on the contact surfaces between the specimen and input/output bars were obtained from the test data recorded by the strain gauges. The specimens were prepared by a three-dimensional printer with plaster and binder. Each specimen modeled a rock mass with one joint with different roughness. The seismic quality factor of specimen is also estimated from the proposed approach of wave energy dissipation. The effects of joint roughness on the seismic quality factor of rock mass and the wave energy attenuation across the rock mass are analyzed from test results.