Crack propagation mechanism of compression-shear rock under static-dynamic loading and seepage water pressure

ZHOU Zhi-hua(周志华)^{1, 2}, CAO Ping(曹平)¹, YE Zhou-yuan(叶洲元)²

(1. School of Resources and Safety Engineering, Central South University, Changsha 410083, China;
2. School of Energy and Safety Engineering, Hunan University of Science and Technology, Xiangtan 411201, China)

Abstract:To reveal the water inrush mechanics of underground deep rock mass subjected to dynamic disturbance such as blasting, compression-shear rock crack initiation rule and the evolution of crack tip stress intensity factor are analyzed under static-dynamic loading and seepage water pressure on the basis of theoretical deduction and experimental research. It is shown that the major influence factors of the crack tip stress intensity factor are seepage pressure, dynamic load, static stress and crack angle. The existence of seepage water pressure aggravates propagation of branch cracks. With the seepage pressure increasing, the branch crack experiences unstable extension from stable propagation. The dynamic load in the direction of maximum main stress increases type I crack tip stress intensity factor and its influence on type II crack intensity factor is related with crack angle and material property. Crack initiation angle changes with the dynamic load. The initial crack initiation angle of type I dynamic crack fracture is 70.5°. The compression-shear crack initial strength is related to seepage pressure, confining pressure, and dynamic load. Experimental results verify that the initial crack strength increases with the confining pressure increasing, and decreases with the seepage pressure increasing.

Key words:static-dynamic loading; seepage pressure; stress intensity factor; initiation of crack