岩石材料的三维各向异性损伤破坏模型与数值模拟

A three-dimensional anisotropic damage model of rock materials and its numerical simulation

基于复合材料以及连续介质损伤理论,给出了岩石材料的各向异性损伤破坏模型。通过引入与岩石材料单轴加载行为相对应的特征模态构成的四阶对称损伤张量,描述了岩石材料的损伤演化过程,其中对不同主应变方向采用不同的损伤变量,而对同一主应变方向拉压时的损伤则采用不同的损伤变量来描述。在数值模拟岩石破坏过程的程序中,采用了张量分解的方法。将该模型编写用户材料子程序,并嵌入到大型有限元分析程序 ABAQUS 中,通过 ABAQUS/EXPLICIT SOLVER 的显式有限元算法求解。利用此程序对岩石材料的单轴压缩进行了数值模拟。

Based on research results of composite material and continuum damage mechanics theory,a three-dimensional anisotropic damage model was presented.To describe the damage evolution of rock material during loading/unloading,the derivate eigenmodes in the proposed model are assumed to be related with the uniaxial behavior of the rock material.Each eigenmode has a corresponding damage variable due to the fact that damage is a function of the magnitude of the eigenstrain.Within an eigenmodes,different damage variables can be used for tension and compression.Hence,these damage variables in six eigenmc,des can form a 4th rank symmetric damage tensor which stipulates evaluation of effective elastic modulus of the rock material with microcracks and an adequate description of the evolution of damage. In this model,the tensor decomposition technique is employed.It means that the stress and strain tensors are decomposed into six eigentensors,which correspond to six eigenvalues accordingly.The stress-strain curves for different directions,which can be obtained from the experiment,are assumed to be different in each normal eigenmodes. This model was also developed into finite element code in explicit format;and the code was integrated into the well-known computational environment ABAQUS using the ABAQUS/Explicit Solver.Numerical simulation of an uniaxial compressive test for a rock sample is used to examine the performance of the proposed model.The results of the numerical simulation show that it is possible to reproduce most of the observable characteristics of anisotropic behavior and damaged zone in rock materials.