It is important to analyze the rock crack initiation, propagation and coalescence in fractured rock mass. At present, the 3D crack evolution process of pre-flawed rock has not been comprehensively studied during the deformation. In this study, uniaxial compression tests were carried out on cylindrical sandstone specimens with two pre-existing flaws with various ligament inclination angles. The crack evolution process at the front surface of the specimen was analyzed by photographic and AE monitoring. In addition, a 3D discrete element modelling was conducted to explore the spatial crack evolution behaviors during compressive loading. Both the numerical strength and final failure modes of specimens were consistent with those obtained in the laboratory experiment. The numerical simulation results revealed that the internal crack distribution was not always identical along the thickness direction. Two types of crack coalescence were identified. The experimental and numerical results enhance the understanding of 3D crack evolution mechanism of fractured rock under external loading.

分析裂隙岩体中岩石裂纹的萌生、扩展和聚结具有重要意义。目前，对预裂岩在变形过程中的三维裂纹演化过程还没有进行全面的研究。在这项研究中，对具有两个不同韧带倾斜角的预先存在的缺陷的圆柱形砂岩试样进行了单轴压缩试验。通过摄影和AE监测分析了试样前表面的裂纹演化过程。此外，还进行了 3D 离散元建模以探索压缩加载过程中的空间裂纹演化行为。试样的数值强度和最终破坏模式均与实验室实验结果一致。数值模拟结果表明，沿厚度方向的内部裂纹分布并不总是相同。鉴定了两种类型的裂纹合并。实验和数值结果增强了对外部载荷作用下裂隙岩石 3D 裂纹演化机制的理解。