Pore-like flaws, which are commonly encountered in brittle rock, play an important role in the engineering performance of structures constructed in or on rock. Experimental and numerical investigations of micro-cracking mechanism of rock containing a pore-like flaw can enhance our knowledge of rock damage/failure from a microscopic view. In this study, the influences of a two-dimensional circular pore-like flaw with respect to its diameter and position on the strength and micro-cracking behavior of brittle rock under uniaxial compression are numerically investigated. The results reveal that the strength and elastic modulus are significantly affected by the diameter and position in the pore. The uniaxial compressive strength and elastic modulus of the numerical model with a pore diameter of 15.44 mm located in the center of the model are found to decrease by 58.6% and 56.4% respectively when compared with those of the intact model without a pore. As the pore position varies while the porosity remains unchanged, the simulated uniaxial compressive strength and elastic modulus are also found to be generally smaller than those of the intact model without a pore. When a pore-containing numerical model is loaded, the micro-cracks are found to mostly initiate at the top and bottom of the pore, due to the local tensile stress increase. The simulation results of the early-stage micro-cracking process and stress distribution are in a generally good agreement with the analytical solution obtained from the Kirsch equations. The grain-based model used in this study can not only study the crack initiation on the boundary of the pore but also provide a convenient means to analyze and visualize the temporal and spatial micro-cracking process after the crack initiation, which accounts for the variations in the simulated strength and modulus satisfactorily from a micro-cracking view.

中文翻译：

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含孔状缺陷脆性岩石单轴压缩微裂纹行为数值研究

脆性岩石中常见的孔状缺陷对岩石中或岩石上建造的结构的工程性能起着重要作用。对含有孔隙状缺陷的岩石微裂纹机制的实验和数值研究可以从微观角度增强我们对岩石损伤/破坏的认识。在这项研究中，数值研究了二维圆形孔状缺陷的直径和位置对单轴压缩下脆性岩石强度和微裂纹行为的影响。结果表明，强度和弹性模量受孔隙直径和位置的显着影响。孔径为15的数值模型的单轴抗压强度和弹性模量。发现位于模型中心的 44 mm 与没有孔隙的完整模型相比分别减少了 58.6% 和 56.4%。由于孔隙位置变化而孔隙率保持不变，模拟的单轴抗压强度和弹性模量也普遍小于没有孔隙的完整模型。当加载含孔隙的数值模型时，发现由于局部拉伸应力的增加，微裂纹主要在孔隙的顶部和底部开始。早期微裂纹过程和应力分布的模拟结果与由Kirsch方程得到的解析解基本吻合。