循环加卸载作用下的岩石损伤本构模型

A Damage Constitutive Model of Rock under Cyclic Loading and Unloading

为了研究循环加卸载作用下岩石的力学特性和应力应变关系,以砂岩为研究对象进行循环加卸载试验。基于岩石微元强度服从Weibull分布和岩石破坏服从最大正应力理论的特点建立岩石损伤本构模型;引进线性拟合的方法确定模型参数值,从而验证本构模型的合理性,并对参数进行敏感性分析;通过循环加卸载应力应变曲线的特点,分析砂岩的力学特征。研究表明,砂岩是弹塑性材料,在每阶段均有弹性变形和塑性变形;砂岩残余应变逐渐累积,滞回环面积、变形模量逐渐增大;基于最大正应力理论的岩石损伤本构模型能准确反映砂岩在循环荷载作用下的应力应变关系;本构模型参数具有明确的物理意义。

In order to study the mechanical properties and stress-strain relationship of rock,cyclic loading and unloading tests were carried out on sandstone.Based on the Weibull distribution that rock micro-unit strength obeys and the maximum normal stress theory that rock failure obeys,a rock damage constitutive model was built up;the parameters of the model were determined by introducing linear fitting method to verify the rationality of the constitutive model,and the sensitivity of constitutive parameters was analyzed;the characteristics of cyclic loading and unloading stress-strain curve were used to analyze sandstone mechanical characteristics.The results show that sandstone is an elastic-plastic material,which has elastic deformation and plastic deformation at every stage;residual strain of sandstone gradually accumulates,the area of hysteresis loop and the deformation modulus gradually increase;the rock damage constitutive model based on maximum normal stress theory can accurately reflect the stress-strain relationship of sandstone under cyclic loading and unloading;the parameters of constitutive model are obviously of physical significance.