Experimental investigation of jointed rock breaking under a disc cutter with different confining stresses

Extensive and detailed investigations have been made to better understand the rock-breaking mechanism of the tunnel boring machine (TBM) disc cutter, but the crack propagation and failure modes induced by the disc cutter when the confining stresses and joint characteristics vary have not been comprehensively investigated. To address this area of research, a triaxial testing machine (TRW-3000) is modified to investigate the effect of different confining stresses (0, 2.5, 5, 7.5 and 10 MPa) on the rock breaking of different joint angles (0°, 30°, 60°, and 90°) induced by the disc cutter. In this series of tests, the crack propagation and failure modes of the intact and jointed rock with different confining stresses are analysed. During the experiments, four different types of failure modes have been observed. The failure mode is affected by the joint orientation at low confining stress. The existence of joints has no obvious effect on the failure mode when the confining stress increases to a certain extent.