Study on elasto-plastic zoning radius and failure characteristics of layered rock with a single hole under impact loading

The zonal rupture phenomenon of surrounding rock in deep mining roadways is a complex nonlinear damage phenomenon, which poses a serious threat to the safety of roadway support. The zonal rupture mechanism of laminated rock under dynamic loading is crucial for optimizing the support design. In order to simulate the zonal rupture phenomenon of surrounding rock, this paper adopts the separated Hopkinson press bar system (SHPB) to conduct triaxial dynamic impact tests on the layered slate with a center hole, simulating the zonal rupture phenomenon of layered slate under different laminar inclination angles, impact loads, and surrounding pressure conditions. At the same time, based on the theory of elastic-plastic mechanics, the calculation formula of the elastic-plastic zoning radius of the slate specimen was deduced. Its correctness was verified through the test, and the damage mechanism of zonal rupture was analyzed in depth. The results showed that: (1) Radial tensile damage dominated the boundary of the zones, but the stress concentration in the laminated surface caused the crack to turn to the shear surface to form a penetrating fissure. (2) The dynamic compressive strength and zonal radius increased with the increase of impact load and surrounding pressure. Specimens with lower strengths have larger zonal radii and take shorter time to reach the peak.