通过直剪条件下的力学模型试验, 结合对模型破坏过程中声发射特征参数的分析,揭示了岩体在不同宽度岩桥和法向应力条件下的破坏特征。结果表明随着岩桥宽度的增加,破坏面起伏度、粗糙度都相应增大;随着法向应力的增加,破坏面的起伏程度和粗糙度减小,峰值剪切应力不断增大;不同岩桥宽度和法向应力导致岩体产生不同方式的破坏,包括剪断破坏、拉剪复合破坏和剪切破坏;声发射阶段性特征与岩桥贯通破坏过程一致,声发射事件数峰值随岩桥宽度和法向应力的增大而增大,其峰值出现时间在剪切应力达到峰值之后。研究结果为判别不同宽度岩桥变形与破坏各个阶段提供依据。

The failure characteristics of rock mass under different widths of rock bridge and normal stresses were revealed through mechanical model test in association with analyzing the characteristic parameters of acoustic emission during the failure process. Results showed that with the increase of the width of the rock bridge, the fluctuation of failure surface and the roughness of the surface both increased. With the increase of normal stress, the peak shear stress increased continuously but the degree of fluctuation and roughness of the failure surface decreased. The failure modes of rock bridges of different widths under different normal stresses varied, including cutting damage, tensile-shear composite failure, and shear failure.The characteristics of acoustic emission were consistent with the failure process of the rock bridge, and the peak value of AE events, which appeared after the peak of shear stress, increased with the increase of the width of rock bridge and the normal stress.The results provide basis for identifying different destruction stages of rock bridge with different widths.