Tensile behavior of rock under intermediate dynamic loading for Hwangdeung granite and Linyi sandstone

Intact rock is most prone to tensile failure. However, the behavior of tensile rock failure between static loading and dynamic loading is unlike. Research on the effect of load/strain rate on the behavior of rock and rock-like material has been attempted massively by many investigators. However, the data in the range between static and dynamic, i.e., intermediate strain rate (ISR), remains unexplored. To determine tensile strength and observe its behavior under intermediate strain-rate loading, specialized loading device using an explosive-driven piston was designed. Compared to Split-Hopkinson Pressure Bar (SHPB), which is commonly used in dynamic testing, the device adopted by this study produces a lower loading rate that is in the range of ISR loading. Two types of rock, namely Hwangdeung granite and Linyi sandstone, was collected for the test. The results indicate that the tensile strength increases with increasing strain rate. The increasing slope is more significant in the higher strain rate than in the lower strain rate. Failure behavior corresponds to a numerical simulation performed by ANSYS AUTODYN. This finding is essential for better understanding of real engineering problem such as rock and cutting tool interaction during rock excavation process.