脆性岩石热-水-力耦合应力强度因子计算

摘要

A new calculation formula of THM coupling stress intensity factor was derived by the boundary collocation method, in which an additional constant stress function was successfully introduced for the cracked specimen with hydraulic pressure applied on its crack surface. Based on the newly derived formula, THM coupling fracture modes (including tensile, shear and mixed fracture mode) can be predicted by a new fracture criterion of stress intensity factor ratio, where the maximum axial load was measured by self-designed THM coupling fracture test. SEM analyses of THM coupling fractured surface indicate that the higher the temperature and hydraulic pressure are and the lower the confining pressure is, the more easily the intergranular (tension) fracture occurs. The transgranular (shear) fracture occurs in the opposite case while the mixed-mode fracture occurs in the middle case. The tested THM coupling fracture mechanisms are in good agreement with the predicted THM coupling fracture modes, which can verify correction of the newly-derived THM coupling stress intensity factor formula.%采用边界配置法并引入附加的常应力函数，成功地推导出岩石热-水-力(THM)耦合条件下含裂纹试件(裂纹面有水压作用)的裂尖应力强度因子计算公式。利用自行设计的THM耦合断裂试验，测定脆性岩石THM耦合断裂的最大轴压，并依据新推导的公式和新型应力强度因子比断裂准则预测脆性岩石THM耦合断裂模式。岩石THM耦合断口的形貌特征分析结果表明：温度、水压越高，围压越低，沿晶(拉伸)断裂越容易发生；反之，则穿晶(剪切)断裂更容易发生；而介于两者中间时，则复合型断裂更容易发生。测得的 THM 耦合断裂机理与预测的THM耦合断裂模式结论一致，从而验证了推导出的THM耦合应力强度因子计算公式的正确性。