加载历史对岩石热开裂破坏的影响

Impact on rock's thermal cracking by loading history

为了解决现有研究一般不考虑加载和加温的顺序,不论引起其热开裂破坏的加载历史如何,认为只要所加的载荷和温度值相同,其损伤演化过程和破坏强度将相同的问题。结合带扫描电镜的岛津SEM高温疲劳实验系统实时观测了石灰岩在不同加温和加载顺序下的热开裂破坏过程。从岩石微裂纹扩展的角度,计算不同加载顺序下其裂端能量释放率。理论与实验结果表明:岩石热开裂破坏受加载历史的影响,加温加载对岩石损伤破坏的影响是非线性耦合关系,高应力、低温和低应力、高温必须考虑其热-力耦合效应。岩石的热损伤是不可逆的,它会受加温历史的影响,在不同的加载顺序下其结果不同。

Currently there is no consideration on the order of loading and heating in studying rock thermal fracturing. In despite of load＇s history, it is normally believed that the rock thermal fracture is same if the loading and heating is same. In order to demonstrate the impact on rock＇s damage and fracturing by the history of loading and heating, this study conducts a meso-structure experiment to observe the process of limestone＇s thermal crack damage under the different order of loading and heating in real time. The instruments include Dao Jin High Temperature Fatigue Testing System with Scanning Electron Microscope. Monitoring the rock＇s tiny crack growth, the study computes its crack tip energy release rate under different order of loading. The theoretical and experimental results show that the fracture of rock＇s thermal cracking is significantly affected by loading history. The effect of loading-heating order on rock＇s damage fracture is a non-linear coupling relationship. Under high stress and low temperature or low stress and high temperature, the coupling influence of thermal-mechanical must be considered. Rock＇s thermal damage is irreversible and impacted by heating history. The results will be different under different order of loading.