中文摘要：

通过开展不同卸荷速率下大理岩加轴压、卸围压室内试验与颗粒流仿真,采用多角度宏细观结合分析的方法,探讨卸荷速率对脆性岩石卸荷破坏机制的影响效应。结果表明：岩样宏观表现的剪切破坏细观上是拉破坏扩展形成的贯通破坏面。黏结能、应变能同时出现负向增长的特征,可以作为脆性岩石的破坏前兆。高卸荷速率下岩样内部会出现多条贯通性破坏面,次要破坏面明显,张拉破坏裂纹分布面积较大。卸荷速率增加,峰值点至应力突降处的拉裂纹增长率越高;低卸荷速率时剪裂纹数偏高。卸荷速率会改变岩样破坏前声发射计数率的增长速率、破坏点附近的计数率量值以及破坏后的波动幅度。卸荷速率增加会引起黏结能、应变能以及摩擦能的减少,动能则相反。

英文摘要：

Loading axial compression and unloading confining pressure tests and simulations of particle flow under different unloading rates have been performed,and effects of unloading rate on unloading failure process of brittle rock have been analyzed by multi-perspective macro-meso methods. The results show that,specimens show shear failure in the macroscopic,but show connective failure plane caused by tensile cracks propagation in the microscopic. The phenomenon of bond energy and strain energy simultaneously show the characteristic of negative growth,which could be known as failure precursor of brittle rock. There are several connective failure planes containing discontinuous joints,obvious secondary shear planes and larger distribution area of tensile cracks under high unloading rates. The growing rate of tensile cracks between peak point and inflection point of axial stress grows as unloading rate increases;there are higher shear cracks under low unloading rate. Growing rate of acoustic emission count rate before failure,count rate value around failure and count rate range after failure depend on unloading rate. An increase of unloading rate could cause bond energy,strain energy and friction energy to increase,but kinetic energy to decrease.