Effect of high-temperature and strain rate on the mechanical and cracking behaviors of flawed sandstone under dynamic impact loading

Abstract

A deep understanding of how flawed rock cracks under high temperatures and dynamic impacts is crucial for safe deep rock engineering design and operation. Dynamic impact tests were conducted on sandstones with various flaw inclinations using a Split Hopkinson Press bar (SHPB) system at room temperature and after high-temperature treatment at 600 °C. The results show that the dynamic peak stress and energy consumption of rock were reduced by thermal treatment. The study identified the circular tensile- and compressive-tangential stress zones around the flaw boundary using elastic theory. The strain accumulation zones gradually shift from the tensile- to the compressive-tangential stress zones as the flaw inclination increases, resulting in a larger crack initiation angle and opening displacement, while also constraining the propagation path. Additionally, the high-temperature treatment strengthened the deformation in the circular tensile-tangential stress zone. In contrast to the severe failure of specimens at room temperature, the clear failure pattern of the specimens after high-temperature treatment merely consists of wing cracks. Finally, this study presents a detailed theoretical explanation of the cracking behavior under various conditions, which is consistent with the experimental results. This research enhances the understanding of dynamic crack propagation in deep high-temperature rocks and provides scientific references for engineering safety design and protection.