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断裂岩石在长期地质力学作用下发生蠕变,并伴有声发射,此声发射规律可为岩石稳定性监测和预警提供有益借鉴。为了研究断裂岩石蠕剪过程的声发射特征,在法向力恒定的条件下,对巴西拉破坏和压剪破坏2种不同形式的断裂砂岩进行蠕变分级剪切试验,并运用全信息声发射信号分析仪进行实时监测,得到2种不同破坏形式的断裂岩石在不同蠕剪阶段声发射能量和蠕变剪切位移关系。同时,利用声发射定位系统对蠕剪过程中断裂岩石的双翼啮合和磨损进行定位,结合断裂面等高线图,预测断裂岩石在长期蠕剪中的破坏位置和破坏形式。试验结果表明:断裂岩石蠕剪失稳前声发射信号缺失;巴西拉破坏岩样蠕剪中后期声发射能量出现波峰,每段剪切位移加载前期能量达到局部最大值,之后呈现下降趋势;压剪破坏岩样蠕剪中期声发射能量出现低谷,每段剪切位移加载中期声发射能量出现局部波峰。同时,由声发射定位可知,2类断裂岩石啮合面中心部位都最先发生破坏,断裂面蠕变剪切的初期破坏具有方向性,破坏初期沿断裂面呈现带状分布并与剪切方向垂直。
Fractured rocks creep under the long-term geomechanical action accompanied by acoustic emission. The acoustic emission law can provide useful references for rock stability monitoring and early warning. In order to study the characteristics of acoustic emission in the creep process of fractured rock, creep grading shear tests were carried out on two different types of fractured sandstone under the same normal force with Basilar failure and pressure-shear failure. With full information acoustic emission Signal analyzer for real-time monitoring to obtain the relationship between the acoustic emission energy and the creep shear displacement of two different types of fractured rock at different creeping-shear stages. At the same time, the acoustic emission positioning system was used to locate the double-wing meshing and wear of the fractured rock during creep shear. The location and the failure mode of the fractured rock in the long-term creep shear were predicted based on the contour map of the fracture surface. The experimental results show that the acoustic emission signal is absent before the creep shear instability of the fractured rock. The acoustic emission energy peak appears in the middle and late stage of the Basila pull-off shear creep shear, and the energy reaches the local maximum at each shear displacement loading stage and then decreases. The pressure Shear damage rock-like medium-term sound shear energy creep appeared low trough, mid-stage shear displacement of each load acoustic emission energy appears local peaks. At the same time, it can be seen from the acoustic emission positioning that the center of the meshing surface of the two types of fractures is the first to be damaged. The initial failure of creep shear in the fracture surface has the directionality. In the initial stage of failure, the fracture surface presents a zonal distribution and is perpendicular to the shear direction .