为了评估岩体在高温和压剪工况下的稳定性，利用声发射技术对25~800 ℃处理后的红砂岩进行了变角剪切下声发射特性研究，分析了高温对红砂岩剪切断口微观特性的影响机理。结果表明：（1）高温作用使得红砂岩的声发射事件由常温下低活跃度的间接性活动向高活跃度的连续性活动转化；（2）随着热处理温度的升高，砂岩在压剪状态下的剪切裂纹所占比例逐渐增大，损伤剪切应力阈值减小，裂纹非稳定扩展阶段延长；（3）当剪切角度为55°时，高温对红砂岩的剪切损伤发展具有抑制作用，而当剪切角度为65°时具有促进作用；（4）红砂岩压剪断口形貌主要以沿晶体解理切断（穿晶断裂）形成，但当热处理温度为800 ℃时，更易于沿晶界形成。研究成果可为解决高温岩土工程问题提供参考。

In underground rock engineering，such as deep resource mining and underground nuclear waste repository construction，high temperature is one of the important factors affecting the stability of rock engine-ering structure.Meanwhile，compression-shear stress state is one of the common stress states of rock in engine-ering.Therefore，the research on acoustic emission characteristics and shear fracture micro mechanism of red sandstone under variable angle shear after high temperature treatment is of great significance to monitor and analyze the stability of rock in high temperature rock engineering.By analyzing the acoustic emission characteristics of red sandstone treated at 25~800 ℃ during the shear failure，it can be concluded that high temperature changes the acoustic emission characteristics and related parameters in the shear failure process of red sandstone，including AE event count，b value，RA-AF value and so on.At the same time，based on the acoustic emission characteristics，the influence of high temperature treatment on the shear failure characteristics of red sandstone was analyzed.In addition，the micro mechanism of shear fracture of red sandstone after high temperature was analyzed by electron microscope scanning technology.The test results show that： （1） High temperature makes the change trend of acoustic emission event of red sandstone from indirect activities with low-activity under room temperature to continuous activities with high-density，and the peak value of AE cumulative event count increases with the increase of treatment temperature.（2） According to the distribution characteristics of acoustic emission parameter RA-AF value，it can be concluded that high temperature treatment changes the crack type of red sandstone in compression shear failure，and the proportion of shear crack increases with the temperature increasing.（3） The change trend of AE cumulative event count can be used to judge the shear stress threshold of pore compaction，crack initiation and crack damage.According to the distribution characteristics of the proportion of shear stress threshold，it can be concluded that with the increase of temperature，the proportion of stable crack propagation stage decreases，but the proportion of unstable crack propagation increases.（4） The shear damage characteristics of red sandstone after high temperature treatment were defined by AE cumulative event count.It was found that when the shear angle is 55°，the high temperature treatment can inhibit the development of shear damage of red sandstone，and promote it at 65°.（5） The compression-shear fracture of the samples treated at different temperatures is mainly formed by cleavage along the crystal （trans-granular fracture），but at 800 ℃，it is more prone to failure along the grain boundary，the number of residual dimples increases，the plasticity increases and the degree of fragmentation decreases.The research results can provide reference for solving the problems of high temperature geotechnical engineering.

http://www.goldsci.ac.cn/article/2022/1005-2518/1005-2518-2022-30-5-764.shtml