基于统一强度理论的岩石统计损伤软化本构模型及其参数研究

Study on Rock Statistical Damage Softening Constitutive Model and Its Parameters Based on the Unified Strength Theory

假设岩石材料的损伤服从三参数Weibull分布,首先引入损伤阀值的思想,建立岩石统计损伤演化模型;其次,基于统一强度理论和Lemaitre应变等价性假设,引入Lode参数,建立一种可以考虑中间主应力的岩石统计损伤软化本构模型,并推导出模型参数的解析解;最后,通过与试验结果进行对比,验证了所建立的统计损伤本构方程及其参数确定的合理性。研究结果表明:该本构模型参数获取简单,能够较好地反映岩石的偏应力-应变关系,尤其是各级围压下的岩石损伤初始点和峰后应变软化特性。

Assuming that the damage of rock obeys the three-parameter Weibull distribution,the statistical damage evolution model was established by adopting the idea of damage threshold.Then,based on the unified strength theory and the Lemaitre strain equivalence hypothesis,by introducing Lode parameters,a rock statistical damage softening constitutive model which can consider the in-termediate principal stress was established,and the an-alytic solution of the model parameters was deduced.Finally,through comparing with the experimental results,the rationality of the statistical damage constitutive equation and its parameters was verified.The results showed that the proposed constitutive model could well predict the relationship between stress and strain of rock,especially the initial point of rock damage and the characteristic of post-peak strain softening under different confining pressures.