Experimental study on triaxial disturbance and failure characteristics of rock-like specimens

WANG Jun; ZHU Chuangen; LI Xun; WANG Bo; ZHANG Yiteng

Abstract：To investigate the disturbance and failure mechanisms within high-stress surrounding rocks,this study conducted triaxial conventional compression and cyclic disturbance tests on rock-like specimens under various confining pressures,elucidating the specimens'disturbance stress-strain behavior and deformation failure charac-teristics.Additionally,Nuclear Magnetic Resonance(NMR)imaging tests were performed to delve deeper into these mechanisms from a microscopic standpoint.The findings reveal:(1)Under varying confining pressures,each specimen exhibited a threshold strength,beyond which axial deformation became markedly sensitive to dis-turbances,leading to significant specimen deformation upon reapplication of disturbances.Below this threshold,deformation showed insensitivity to disturbances.The ratio of threshold to ultimate strength reflects the speci-men's resistance to disturbances,which decreases with increasing confining pressure,indicating heightened sensi-tivity to disturbances under high-pressure conditions.(2)A weakening effect was observed in rock-like specimens under disturbance;for instance,specimens exhibited barrel failure under a conventional triaxial confining pressure of 10 MPa,while displaying oblique brittle failure akin to that observed under 5 MPa after disturbance,highlight-ing the transformative impact of disturbances on failure modes.(3)High-stress conditions prompted rock speci-mens to enter a plastic flow state,characterized by internal particle rearrangement and a significant shift in pore size distribution,with a notable decrease in both small and large pores in favor of medium-sized pores,overall reducing the specimen's porosity.These insights advance our understanding of the behavior of high-stress sur-rounding rocks under disturbances,offering valuable perspectives for engineering and geological applications.