Analysis of dynamic compression property and energy dissipation of salt rock under three-dimensional pressure

In the study, a self-developed Split Hopkinson pressure bar apparatus with triaxial confining pressure was used to examine the dynamic compression property of salt rock under confining pressures of 5, 15, and 25 MPa. To examine the dynamic properties of salt rock, Yingcheng salt rock from Hubei province in China was considered. Dynamic stress–strain curves of salt rock under different confining pressures and strain rates were obtained. The results indicated that the peak stress and ductility of salt rock increased with increase in the strain rate although the strain rate strengthening effect of the salt rock was not evident with increase in the confining pressure. The dynamic properties and disintegration characteristics were investigated on the basis of the energy dissipation principle. The energy delivery and transformation in the entire experimental process were analyzed in detail. Under the same confining pressure, the hardening effect of the salt rock was more evident with increase in the incident energy, and this can be explained by the decrease in the energy transmission/absorption rate when the reflectance rate increased. Contrary to the plastic damage characteristics under quasi-static triaxial compression, the salt rock exhibited evident brittle fracture characteristics under dynamic compressive loading. The peak stress of the salt rock revealed different trends with the increase in energy absorption under different confining pressures. Increased energy absorption and higher peak stress were observed under low confining pressure. However, the peak stress significantly decreased with increase in the energy absorption under high confining pressure.