Experimental and numerical study of the failure process and energy mechanisms of rock-like materials containing cross unpersistent joints under uniaxial compression

Abstract

Joints and fissures in natural rocks have a significant influence on the stability of the rock mass, and it is often necessary to evaluate strength failure and crack evolution behavior. In this paper, based on experimental tests and numerical simulation (PFC2D), the macromechanical behavior and energy mechanism of jointed rock-like specimens with cross nonpersistent joints under uniaxial loading were investigated. The focus was to study the effect of joint dip angle α and intersection angle ? on the characteristic stress, the coalescence modes and the energy release of jointed rock-like specimens. For specimens with ? = 30Ê and 45Ê, the UCS (uniaxial compression strength), CIS (crack initiation stress) and CDiS (critical dilatancy stress) increase as α increases from 0Ê to 75Ê. When ? = 60Ê and 75Ê, the UCS, CIS and CDiS increase as α increases from 0Ê to 60Ê and decrease when α is over 60Ê. Both the inclination angle α and intersection angle ? have great influence on the failure pattern of pre-cracked specimens. With different α and ?, specimens exhibit 4 kinds of failure patterns. Both the experimental and numerical results show that the energy of a specimen has similar trends with characteristic stress as α increases.