Abstract: Based on the actual situation of excavation disturbance in underground rock engineering, it is of theoretical significance and engineering application value to carry out rock joints shear tests that consider the continuous excavation effect and fully reflect the stress adjustment process of the rock joints. In this paper, the shear tests under conventional stress path and continuous excavation effect were conducted on the rock joints prepared by artificial splitting method, and the shear mechanical properties, acoustic emission (AE) characteristics and energy evolution of rock joints under two conditions were systematically studied. The research results show that the greater the intensity of excavation disturbance load, the larger the overall shear stress drop when shear damage occurs at the rock joints, but the maximum value of shear stress drop under continuous excavation effect is only 48.57% of the shear stress drop under conventional stress path. The AE activity in the shearing process of rock joints considering the continuous excavation effect is mainly concentrated when the rock joints is failed by shear and the shear stress drop is generated, the intensity of AE activity is positively correlated with the intensity of excavation disturbance, and the extremum of the change rate of AE count is significantly smaller than the counterpart under conventional stress path. The intensity of crack development, the wear area and failure degree of rock joints in the specimens under the continuous excavation effect increase with the intensity of excavation disturbance, but the intensity of crack development and the failure degree of rock joints in the specimens are less than those under conventional stress path. The elastic strain energy at the shear failure of rock joints considering the continuous excavation effect increases with increasing disturbance load and is lower than that under conventional stress path. The continuous excavation effect reduces the shear strength of the rock joints, but is more likely to trigger shear failure of the rock joints.

Key words: rock joint, continuous excavation effect, shear mechanical properties, acoustic emission (AE), failure property, energy evolution