循环载荷作用下岩石单轴压缩破坏过程的平面弹塑性细胞自动机模型

PLANE ELASTOPLASTIC CELLULAR AUTOMATA MODEL OF FAILURE PROCESS OF ROCKS UNDER CYCLIC LOADING

采用平面弹塑性细胞自动机模型在细观尺度上模拟应变软化岩石类材料的单轴压缩破坏过程。在平面弹性力学细胞自动机的基础上,推导分析平面弹塑性问题的细胞自动机更新规则,开发二维岩石弹塑性细胞自动机数值模拟软件;模拟不同均质度岩石的单轴压缩破坏过程,并在应力峰值后区考虑反复加卸载过程。模拟得到的岩石单轴压缩条件下的全程应力-应变曲线与典型的加卸载应力-应变试验曲线吻合较好,模拟得到的声发射曲线很好地反映出岩石声发射的Kaiser效应。

The elastoplastic cellular automata model for plane problem is set up to model failure process of rocks under uniaxial compression in meso-scope.The cellular automaton is an efficient method to model the process of self-organization of complex system by constructing some local simple rules.It has advantages of localization,parallelization etc..Also,it can consider the heterogeneity of materials.Based on elastic cellular automata,the elastoplastic updating rule is proposed and the numerical program of two-dimensional elastoplastic cellular automata for rocks is developed.The basic thought to model failure process of rocks is to(1) discretize the rock sample into the system which is composed of cell elements;(2) introduce the heterogeneity of rock by generating mechanical parameters such as strength,elastic modulus etc.for each cell elements randomly;(3) update the states of all the cells according to the elastoplastic updating rule;(4) judge whether the cell elements fail or not according to certain failure criterion;and(5) perform the failure analysis to the failed cell elements with elastoplastic theory.The model is used to simulate the failure process of inhomogeneous rocks,and the unloading-loading process in the post peak region is considered.The complete stress-strain curve perfectly agrees with the experimental one.Meanwhile,the strain-acoustic emission(AE) curve obviously indicates the Kaiser effect.