中文摘要：

采用颗粒流软件PFC2D实现含有不同岩桥倾角的预制双裂纹材料在单轴压缩作用下裂纹扩展贯通过程,并利用函数模块追踪裂纹扩展过程和微裂纹数量。数值结果表明：在单轴压缩作用下随着岩桥倾角增大,岩桥区域裂纹贯通模式由张拉型（≤68°）逐渐演化为拉剪复合型（=90°和113°）和剪切型（=135°）;试件峰值强度逐渐降低;并认为宏观的次生剪切带主要由张拉型微裂纹和少量剪切型微裂纹组成。利用室内模型试验对数值结果进行验证,结果表明颗粒流程序能够很好地模拟裂纹贯通过程。

英文摘要：

By using a particle flow code--PFCD, numerical simulations on samples containing two parallel cracks with different rock bridge angles under uniaxial compression are conducted to research the cracks propagation and coalescence. The cracks propagation process and the number of microcracks have been tracked by functions in PFC. Numerical results show that： with the increasing of rock bridge angle under uniaxial compression, the crack coalescence patterns gradually evolve from tensile mode（β〈68） to tensile-shear mixed mode（fl= 90 and 113） and shear mode（β = 135 ）; and the samples＇ peak strengths gradually decrease. The macroscopic secondary shear zone mainly comprise of tensile microcracks and bits of shear microcracks. Comparison between the numerical simulation results with the experiment results indicates that PFC can simulate the crack coalescence process properly.