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将渐近展开法与细观统计模型相结合,研究了脆性岩石双尺度计算方法。该方法在细观尺度定义材料属性,假定材料参数符合Weibull分布,采用弹性-理想脆性本构模型,脆断标准采用修正的Mohr-Coulomb准则和最大拉应力准则,通过宏细观尺度耦合计算,得到细观尺度材料损伤演化及其对结构宏观性状的影响。方法包括确定材料统计参数、确定细观尺度代表性体积单元(RVE)及求解边值方程等步骤。数值模型采用商业软件ABAQUS及其内嵌的UMAT用户子程序实现。该方法适用于岩石单轴受压或低围压应力状态,考虑到计算效率,计算时宜采用混合尺度,即模型重点(关键)部位采用双尺度,而其他区域采用单尺度计算。宏观尺度材料软化后未采用正则化方法,此时的计算结果有网格依赖性。
Asymptotic expansion method and mesoscopic statistical model are combined to study the two-scale calculation method of brittle rock. The method defines the material properties at the mesoscopic scale. The material parameters are in accordance with the Weibull distribution, the elastic-ideal brittle constitutive model, the brittle fracture criterion using the modified Mohr-Coulomb criterion and the maximum tensile stress criterion, The damage evolution and its effect on the macro-structure of the microstructure are obtained. Methods include determining material statistical parameters, determining the meso-scale representative volume unit (RVE), and solving the boundary value equation. The numerical model is implemented using the commercial software ABAQUS and its embedded UMAT user subroutine. The proposed method is suitable for rock under uniaxial compression or low confining stress. Considering the computational efficiency, the mixing scale should be used in the calculation. That is, the model should be double-scale for the key part and single-scale for the other regions. After the macroscale material is softened, the regularization method is not used, and the calculation results at this time are grid-dependent.