Dynamic Fracture Test of Laurentian Granite Subjected to Hydrostatic Pressure

Abstract

Dynamic fracture failure of rocks subjected to static hydrostatic pressure is commonly encountered in deep underground rock engineering. The static fracture behavior of rocks under hydrostatic stress has been well studied in the literature. However, it is desirable to investigate the dynamic fracture failure of rocks under various hydrostatic pressures. In this study, a triaxial split Hopkinson pressure bar (SHPB) system is used to measure the dynamic fracture toughness of rocks under five hydrostatic pressures. The results show that dynamic fracture toughness under a certain hydrostatic pressure enhances with the increase of the loading rate, and the dynamic fracture toughness at the similar loading rate increases with the hydrostatic pressure due to the closure of microcracks in rocks. An empirical formula is proposed to describe the influences of the loading rate and the hydrostatic pressure on the rock dynamic fracture toughness.