压应力状态下断续节理岩体全过程应力-应变关系及其变形局部化分析

利用内变量热力学理论和裂纹孤立理论研究了压应力状态下断续节理岩体的变形局部化问题和全过程应力–应变关系。研究表明全过程应力–应变关系包括线弹性阶段、非线性强化阶段和应变软化阶段。分析了产生应变软化的主要原因,将损伤和变形局部化引入本构模型是和以往本构模型的显著区别。通过实验对比分析,验证了模型的正确性和有效性。

ANALYSIS OF THE COMPLETE STRESS-STRAIN RELATION AND DEFORMATION LOCALIZATION FOR INTERMITTENT CRACK-WEAKENED ROCK MASS UNDER COMPRESSIVE STRESSES

The crack isolating theory combined with internal variable theory including a micro-to-macro transition is applied to study the localization of deformation and the complete stress-strain relation for intermittent crack-weakened rock masses under compressive stresses. The self-similar model is selected as a basic dissipative mechanism underlying macroscopic inelastic deformation. The closed-form explicit expression for the complete stress-strain relation of rock mass is obtained. The complete stress-strain relation includes the stages of linear elasticity,non-linear hardening,and strain softening. The results show that the complete stress-strain relation and the strength of rock mass depend on the crack interface friction coefficient,the crack spacing,the perpendicular distance between the two adjacent rows,the fracture toughness of rock material,and the orientation of the cracks. Special attention is paid to the transition from distribution damage to localization of damage and the transition from homogeneous deformation to localization of deformation. Theoretical predictions are consistent with the experimental results.