基于统一强度理论的岩石三维损伤模型及其验证

A 3-D damage model of geo-material based on unified strength theory and its validation

本文基于岩石损伤、断裂演化的阶段性特征,将岩石应力-应变曲线分为两个阶段,第一阶段依次包括:Ⅰ-无损伤弹性、Ⅱ-微裂纹演化和Ⅲ-宏观裂纹成核三个内部损伤过程,曲线跨越峰值点;第二阶段包括:Ⅳ-宏观裂纹扩展和Ⅴ-摩擦滑动。鉴于此,提出两种不同类型的曲线拟合单轴应力-应变曲线并建立一维损伤模型。在复杂应力状态下,采用统一强度理论构造复杂应力等效应变,从而将一维损伤模型推广为三维损伤模型的统一框架。该模型参数直接取值单轴应力应变曲线,可表现岩石峰值后演化的重要特征如应力跌落、残余强度等。大量实验数据验证表明,模型曲线与实验曲线符合较好。模型可推广于岩土材料、金属的非线性描述。

According to phased characteristics, the stress- strain curve can be divided into two stages.The first stage is the reflection of three continuous damage evolution:I-no damage elastic,II-microcrackevolution and III-macrocrack nucleation. And the second stage reflects the two continuous damage evolu-tion:IV-macrocrack propagation and run-through IV-friction and sliding. Based on these,two types ofmathematic curves are proposed and smoothly connected to fit a uniaxial strain-stress curve,and a 1-Dcontinuum damage model is established. Under the condition of complex stress,the 1-D damage modelcan be generalized to establish a 3-D damage model by using the Unified Strength Criterion(USC)to forma equivalent strain. The parameters of the 3-D damage model can be easily obtained from strain-stresscurves under uniaxial and three-axial loading. The model can reflect the important characteristics such asstress-fall and remain-strength. The strain-stress curve of the model is well conformed to that of the ex-perimental data. The model in the paper suggests a unified frame of damage evolution for a variety of mate-rials such as geo-material,plastic materials and metal.