岩石三维弹塑性损伤本构模型研究

Three-dimension elastic-plastic damage constitutive model for intact rock

基于应变等效假设和真实应力概念的弹塑性损伤理论,在真实应力空间内,结合非线性统一强度模型,以广义塑性剪应变为硬化参数,并同时考虑应力水平对硬化速率的影响,建立了无损状态下岩石材料的弹塑性表达式;在名义应力空间内建立考虑围压对损伤速率影响的损伤演化方程,从而建立了岩石材料的三维弹塑性损伤本构模型。本构模型中各物理参数意义明确,与材料试验结果的对比表明,所建立的三维弹塑性损伤本构模型可较好地描述岩石材料在多轴受力情况下的变形与强度特性,为岩体工程的复杂非线性受力分析提供理论依据。

Based on the concept of true stress and the strain equivalence hypothesis, a three-dimension elastic-plastic damage constitutive model for rock is established. Combining the nonlinear unified strength model as the yield function and the equivalent plastic shear strain as the hardening parameter considering the effect of stress level, the formulation of elastic-plastic behavior of rock is deduced in the true stress space. As in the normal stress space, the damage evaluation law is given by considering the effect of confining pressure. The present theoretical results and the test data are compared. It is indicated that the proposed constitutive model describes the strength and deformation behaviors and the strain softening behaviors of rock. Furthermore, the model can be employed to simulate rock engineering structures under multi-dimensional nonlinear stress, providing a basic reference for structural design and analysis.