非均质岩石单轴压缩试验破坏过程细观模拟及分形特性

Meso-simulation and fractal characteristics for uniaxial compression test of inhomogeneous rock

为了细观模拟非均质岩石试样单轴压缩试验的破坏过程,提出了一种新的有限元数值模拟方法。该方法以莫尔-库仑破坏准则为基础,将岩石视为非均质和准脆性材料,并假定岩石单元的抗剪强度参数服从正态分布。有限元细观模拟结果表明,岩样非均质性对本构关系曲线形状有显著影响,模拟的应力-应变曲线与试验曲线基本吻合。基于分形几何理论,采用计盒维数方法计算单轴压缩试验不同荷载条件下的岩石破坏分形维数,建立了分形维数与顶部位移之间的非线性演化模型。分形分析研究表明,岩石试样的破坏过程具有分形特性,分形维数可用来定量地表征单轴压缩试验岩样破坏过程。

In order to simulate fracture process of inhomogeneous rock specimen in meso-scale under uniaxial compres- sion test, a new numerical simulation procedure based on finite element method was proposed. The simulation proce- dure was based on Mohr-Coulomb fracture criterion. Taking rock specimen as inhomogeneous and quasi-brittle materi- al, the shear strength parameters of rock element were subjected to normal distribution. The FEM analysis investigation shows that inhomogeneity of rock specimen has a significant influence on the simulated stress-strain curve and the sim- ulated curve agrees well with the experimental curve. Based on fractal theory, the fractal dimension of rock fracture for different displacement was calculated by using box-counting dimension method. The nonlinear relationship between fractal dimension and displacement at the top was proposed. The fractal analysis investigation show that the fracture of rock specimen has fractal characteristics. Fractal dimension can be used to quantitatively characterize the fracture process of rock specimen under uniaxial compression test.