Effect of reflected stress wave on dynamic crack propagation and arrest behavior of sandstone specimens under impact loading

Abstract

The interaction of stress waves generated by blasting or excavation disturbance with cracks or joints significantly affects the mechanical behavior of rock masses with some pre-existing cracks. To better understand the dynamic damage evolution mechanism of fractured rock mass, the influence of stress waves on cracks in rock mass must be investigated. Thus, to study the effect of reflected stress wave on dynamic fracture behavior of fissured rock mass, a large-size arc-shape boundary single cleavage triangle (ABSCT) configuration sandstone specimen was proposed in the present study. A series of impact tests were performed on the specimen with 0°, 65°, 95°, and 125° ABSCT using the drop plate impact testing system to determine dynamic fracture properties. The test was numerically simulated using the modified finite difference software and the traditional finite element software. The effect of the reflected stress wave caused by the arc-shape boundary of the ABSCT specimen on the crack propagating speed, crack fracture toughness, and compressive stress along the crack trajectory under dynamic loads was analyzed and discussed. The results show that the ABSCT specimen has a crack arresting effect on a propagating crack. The average crack propagation speed of three specimens with arc-shape boundaries is almost 0.63 times that of the flat-bottom specimen, indicating that the arc boundary has an obvious effect on the crack propagating velocity. The average crack propagating speed decreases with the increase in arc boundary radian. The compressive stress on the crack path of three arc boundary specimens is found to be greater than that of the flat-bottom specimen. Furthermore, the crack arrest toughness is greater than the average crack propagating toughness at the arc-shape boundary specimen.