To explore the failure mechanism of rock with holes and fissures, uniaxial compression tests of sandstone samples with combined double hole and double fissure defects were carried out using Particle Flow Code 2D (PFC2D) numerical simulation software. The failure behaviour and mechanical properties of the sandstone samples with combined double hole and double fissure defects at different angles were analysed, and the evolution results of the stress field and crack propagation were studied. The results show that with a decrease in fissure angle, the crack initiation stress, damage stress, elastic modulus and peak stress of the defective rock decrease, while the peak strain increases, and the brittleness of the rock is weakened. Rocks with combined double hole and double fissure defects at different angles lead to different failure modes, crack initiation positions and crack development directions. After uniaxial compression, both compressive stress and tensile stress concentration areas are produced in the defective rock, but the compressive stress concentration is of primary importance. The concentration area is mainly distributed around the holes and fissures and the defect connecting line, and the stress concentration area decreases with the decreasing fissure angle. This study can correctly predict the mechanical properties of rock with combined double hole and double fissure defects at different angles and provide a reference for actual rock engineering.

中文翻译：

---

双孔双裂隙复合缺陷砂岩样品强度及特征数值研究

为探究含孔裂岩体的破坏机理，利用粒子流编码2D（PFC2D）数值模拟软件对具有双孔双裂隙组合缺陷的砂岩样品进行单轴压缩试验。分析了不同角度的双孔双裂复合缺陷砂岩样品的破坏行为和力学性能，研究了应力场和裂纹扩展的演化结果。结果表明，随着裂隙角的减小，缺陷岩石的裂纹萌生应力、损伤应力、弹性模量和峰值应力减小，峰值应变增大，岩石脆性减弱。具有不同角度双孔双裂复合缺陷的岩石导致不同的破坏模式，裂纹萌生位置和裂纹发展方向。单轴压缩后，缺陷岩石中同时产生压应力和拉应力集中区，但压应力集中是主要的。集中区主要分布在孔洞、裂隙和缺陷连接线周围，应力集中区随着裂隙角的减小而减小。该研究可以正确预测不同角度双孔双裂复合缺陷岩石的力学特性，为实际岩石工程提供参考。但压应力集中是最重要的。集中区主要分布在孔洞、裂隙和缺陷连接线周围，应力集中区随着裂隙角的减小而减小。该研究可以正确预测不同角度双孔双裂隙组合缺陷岩石的力学特性，为实际岩石工程提供参考。但压应力集中是最重要的。集中区主要分布在孔洞、裂隙和缺陷连接线周围，应力集中区随着裂隙角的减小而减小。该研究可以正确预测不同角度双孔双裂复合缺陷岩石的力学特性，为实际岩石工程提供参考。