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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。
Through the mechanical model test under the condition of direct shear and the analysis of acoustic emission characteristic parameters in the failure process of the model, the failure characteristics of rock mass under different width of rock bridge and normal stress are revealed. The results show that with the increase of the width of rock bridge, the undulation and roughness of failure surface increase correspondingly. With the increase of normal stress, the undulation and roughness of failure surface decrease and the peak shear stress increases. Different rock bridge widths and normal stresses lead to different failure modes of rock mass, including shear failure, composite shear failure and shearing failure. The acoustic emission characteristics are consistent with the failure process of the rock mass. The peak values of acoustic emission events vary with rock mass The bridge width and the normal stress increase with the increase of the peak appearance time after the shear stress peak. The results provide the basis for judging the deformation and failure of rock bridge with different widths.