持续开挖效应下结构面剪切力学性质与能量特征研究

基于地下岩体工程开挖扰动的实际情况，开展考虑持续开挖效应，充分反映岩体结构面应力调整过程的结构面剪切试验更具理论意义和工程应用价值。采用人工劈裂方法制备岩体结构面，开展了常规应力路径和持续开挖效应下的结构面剪切试验，系统研究了两种条件下结构面剪切力学性质、声发射特征和能量的演化规律。研究结果表明：开挖扰动荷载强度越大，结构面发生剪切破坏时的剪应力降整体上越大，但持续开挖效应下的剪应力降最大值仅为常规应力路径下剪应力降的48.57%；考虑持续开挖效应的结构面剪切过程中声发射活动主要集中于结构面受剪破坏和剪应力降产生时，且声发射活动强度与开挖扰动强度正相关，声发射振铃计数变化率极值明显小于常规应力路径下的相应值；持续开挖效应下试样裂纹发育密集度、结构面磨损区域及破坏程度均随开挖扰动强度增加而增加，但试样裂纹发育的密集程度和结构面破坏程度相对常规应力路径下的情况轻；考虑持续开挖效应的结构面发生剪切破坏时弹性应变能随扰动荷载增大而增大，均低于常规应力路径条件下的弹性应变能值，持续开挖效应降低了结构面剪切破坏的强度，但更易引发结构面发生剪切破坏。

Shear mechanical properties and energy characteristics of rock joints under continuous excavation effect

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.