The long-term stability of jointed rock masses is usually dominated by fault activation, which may be triggered by the dynamic disturbance generated by blasting during mining activities, leading to the occurrence of disasters such as landslides in open-pit and rockbursts in deep mining. The initial stress and dynamic disturbance are key factors that strongly affect the shear creep behavior of rock fractures. In this work, the shear failure instability of rock fractures of sandstone under creep-impact loading was experimentally investigated by using a creep-impact test machine, which allows for applying creep loading and an additional dynamic disturbance on rock fractures. Three stages of shear creep deformation, creep strain rate, and time-to-failure are examined under different creep stress levels and impact energies. Experimental results show that the tangential and normal creep rates increase with the increase of creep stress and impact energy, but the increment of tangential creep rate is higher than that of the normal creep rate. The time-to-failure of the creeping specimen is shortened under high creep stress and large impact energy, while the time-to-failure after the last dynamic disturbance of the specimen is determined by the total impact energy and creep stress level. By using high-speed photography, it is found that the failure types of rock depend on the magnitude of impact energy and creep stress level; that is, rock mainly slides with low stress levels and shears off with high stress levels. In addition, under different impact energy and creep stress levels, the variation of height is between 0.38 and 0.52, while the defined fracture factor, which describes the degree of failure of serrations, is between 0.30 and 0.54. The findings can provide deep insight into the fault sliding mechanism caused by mining activities, which provides theoretical support for the safe mining of ore in fault fracture zones.

中文翻译：

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动载荷干扰岩石裂缝的剪切蠕变变形


节理岩体的长期稳定性通常由断层激活为主，断层激活可能由采矿活动中爆破产生的动态扰动触发，导致露天矿滑坡和深部采矿岩爆等灾害的发生。初始应力和动态扰动是强烈影响岩石裂缝剪切蠕变行为的关键因素。在这项工作中，使用蠕变冲击试验机实验研究了蠕变冲击载荷下砂岩岩石裂缝的剪切破坏失稳性，该试验机允许对岩石裂隙施加蠕变载荷和额外的动态扰动。研究了不同蠕变应力水平和冲击能量下的剪切蠕变变形、蠕变应变速率和失效时间的三个阶段。试验结果表明，切向蠕变速率和法向蠕变速率随蠕变应力和冲击能量的增加而增大，但切向蠕变速率的增量高于法向蠕变速率。在高蠕变应力和大冲击能量下，蠕动试件的失效时间缩短，而试件最后一次动态扰动后的失效时间由总冲击能量和蠕变应力水平决定。利用高速摄影发现，岩石的破坏类型取决于冲击能量的大小和蠕变应力水平;也就是说，岩石主要以低应力水平滑动和以高应力水平剪切。此外，在不同的冲击能量和蠕变应力水平下，高度的变化在 0.38 到 0.52 之间，而描述锯齿破坏程度的定义断裂因子在 0.30 到 0.54 之间。 研究结果可为采矿活动引起的断层滑动机理提供深入的见解，为断层断裂带矿石的安全开采提供理论支持。