To reveal the failure mechanism of jointed rock with through-going joints under unloading conditions, the discrete element method was employed to conduct triaxial loading-instantaneous unloading simulations at different joint inclinations and confining pressures. Based on acoustic emission (AE) source parameters and quantitative seismological theory, the spatiotemporal evolution and dynamic development of rock fracturing processes were systematically analyzed, and the controlling effects of joint inclination and confining pressure on rock failure were clarified. The results show that joint inclination and confining pressure jointly determine the distribution and propagation paths of major fracture zones, from which six shear-dominated and one tension-dominated typical failure modes are identified. Despite varying stress conditions, AE responses exhibit similar characteristics, allowing the entire failure process of jointed rock to be divided into three stages: the AE quiet period, the AE growth period, and the AE outbreak period. In the AE outbreak stage, the total number of AE events, the proportion of high-magnitude events, and the released energy increase significantly, driving rapid fracture propagation, coalescence, and structural failure. During the AE growth stage, the b-value decreases with increasing stress level, where b is the slope of G-R relationship fitted line. While in the AE outbreak stage, elevated shear stress, enlarged fracture scales, and clustered AE spatial distributions result in b-values markedly lower than those during the pre-peak loading stage. These findings provide useful insights into the analysis of failure processes and disaster prediction of deep jointed rock masses.
LIU Fei, WANG Luo, LIANG Chang-hui, WU Xiao-gang, TANG Kai, ZHANG Yong-jun.
Fracture Evolution and Acoustic Emission Response of Jointed Rock with Through-going Joints under Instantaneous Unloading[J].
Science Technology and Engineering, 2026, 26(25): 11002-11010 DOI:10.12404/j.issn.1671-1815.2506268
以上力学实验多为卸荷后再增加轴向荷载模拟岩体工程开挖后应力集中导致的围岩失稳破坏,难以再现实际工程中开挖后围岩的瞬时破坏。三轴加载岩石瞬时卸荷破坏实验过程中AE事件数目巨大,准确定位不同时段的AE事件困难,主要通过AE事件数、能量和波形与频谱分析等探究试样破裂机制和失稳前兆信息[13-15],关于表征岩石内部裂纹发育的AE时空演化特征的研究鲜有报道。数值模拟则可以通过开展重复性试验确定节理岩石的卸载破坏峰值应力,再现岩石的瞬时破坏过程。离散元法(discrete element method,DEM)在模拟岩石非连续变形和破裂方面具有显著优势,被广泛应用于研究岩石的破裂演化过程[16-18]。Liu等[19]采用颗粒流程序(particle flow code,PFC)模拟含单一贯通节理岩石试样的三轴加载单面瞬时卸荷破坏过程,研究了节理倾角、初始围压和卸载点对节理岩石破裂失稳的作用机制。李夕兵等[20]基于大理岩的卸围压颗粒流数值模拟,研究不同卸荷速率下岩石试样的破裂特征和机理,发现快速卸荷时,卸荷后持续点的破坏形态为块体剥落及端部颗粒弹射,出现岩爆现象。孙飞跃等[21]采用三维离散元理论和多晶建模技术,研究了真三轴单面卸荷条件下岩爆孕育全过程,将裂纹演化过程分为平静期、稳定增长、快速增长和全面爆裂阶段。
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