Experimental and numerical study of the dynamic failure behavior of rock materials subjected to various impact loads

An understanding of the effect of strain rate on the dynamic failure and mechanical properties of rock materials is important in the design of rock structures against missile impact or the penetration analysis of projectiles into rock mass. In this study, a pulse shape-controlled Split Hopkinson Pressure Bar system was used to impact rock materials. The impact velocity of the impact bar had been increased to 5m/sec from 30m/sec and complete compressive stress strain curves were obtained to investigate the effect of strain rate on the dynamic failure of the rock materials. The micro-focus X-ray computerized tomography was used to scan the tested samples and the failure process of rock materials were discussed. The numerical simulations on SHPB tests of rock materials were carried out with the explicit finite element software ANSYS LS-DYNA. The incident stress waveforms obtained from the SHPB test are directly applied to the input into the end side of the incident bar. The numerical stress-strain curves are compared with the experimental curves with a different strain rate.