A Damage Constitutive Model for Rock Based on Weibull Distribution Under Coupling Action of Temperature and Confining Pressure
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摘要: 基于Lemaitre应变等价性假设理论,假定受热-力耦合损伤的岩石微元强度服从Weibull分布,考虑温度与围压耦合作用对岩石力学参数的影响,采用损伤力学理论,引入热损伤变量和力损伤变量,在微元破坏符合D-P准则条件下,建立岩石热-力耦合损伤演化方程及本构模型,采用理论推导的方法得出所需的模型参数。通过对比所构建的岩石热-力耦合损伤本构模型曲线和试验曲线的峰值点,结果表明两者吻合度较好,能够很好反映岩石在温度和围压耦合作用下的损伤演化和本构关系,验证了该模型及模型参数确定方法的合理性和可靠性。模型所需的模型参数均可通过实验室常规三轴试验获得。Abstract: Based on Lemaitre’s hypothesis theory of strain equivalence, it was assumed that the micro-element strength of rock subjected to thermal-mechanical coupling damage followed the Weibull distribution. Considering the influence of temperature and confining pressure coupling on rock mechanical parameters, the thermal-mechanical damage variables were introduced by the damage mechanic theory. In the condition that the microelement failure conformed to the D-P criterion, the damage evolution equation for coupling of temperature and mechanics and the constitutive model of rock were established. The required model parameters were derived by the theory. Comparing between the peak points in the established constitutire model curves for thermal-mechanical coupling demage and experimental curves, the results showed that the two curves were in good agreement, the model could well reflect the damage evolution and the constitutive relation for rock in the coupling of temperature and confining pressure. The rationality and reliability of the model and the method to determine the model parameters were verified. The model parameters required by the model could be obtained by conventional triaxial tests in laboratory.
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