花岗岩真三轴加载破坏前兆信息

岩体开挖卸荷导致内部扰动和应力重分布,极易发生突发性失稳破坏。对不同中间主应力下的花岗岩试件进行真三轴加载试验。试验过程中采用高速摄像机、声发射、红外热像仪全程观测,研究岩石加载破坏过程中红外热像演化特、临空面温度变化特征、声发射振铃计数率变化特征、岩石表面裂纹发育,研究岩石破坏前各类监测数据的异常反应。研究表明:热像异常演化对岩石未来表面破裂有指导作用,未来裂纹扩展区域与热像异常出现位置相一致;岩石破坏前临空面上温度会出现异常,一般表现为温度曲线转折性变化和温度跳跃式升高;声发射振铃计数率会在试件失稳破坏前出现密集性增高现象。这些异常现象作为前兆信息为岩石破坏提供预警,研究结果为岩体开挖卸荷后工程灾害预警与防治提供理论参考。

Study on precursor information of red sandstone failure under true triaxial loading

Rock mass excavation unloading leads to internal disturbance and stress redistribution, which is prone to sudden instability. In this paper, a true triaxial loading test is performed on red sandstone specimens under different intermediate principal stresses. During the test, high-speed camera, acoustic emission and infrared thermal imager were used to observe the whole process. The evolution characteristics of infrared thermal image, the characteristics of free surface temperature change, the characteristics of acoustic emission ringing count rate change and the development of rock surface crack were studied. The abnormal response of various monitoring data before rock failure was studied. The results show that the evolution of thermal image anomaly can guide the future surface fracture of rock, and the future crack propagation area is consistent with the location of thermal image anomaly; Before the rock is destroyed, the temperature on the surface of the open space will be abnormal, which is generally manifested as a turning change in the temperature curve and a jump in temperature; The count rate of acoustic emission ringing will increase in density before the specimen is unstable and damaged. These abnormal phenomena provide early warning for rock failure as precursor information, and the research results provide theoretical reference for engineering disaster early warning and prevention after rock excavation unloading.