This study employs numerical simulations to scrutinize the influence of pre-existing fractures and in situ stress states on blast-induced crack propagation in fractured rocks. The geomechanical behavior of fractured rocks is simulated via a particle-based discrete element model with particles constructed and assembled by the Voronoi tessellation scheme based on the grain-size distribution of actual rock samples (specifically, Beishan granite), which captures solid vibrations under dynamic loading and realistically responds to crack growth and fracture displacement. The reliability of the model is also validated using Snell’s law and fracture mechanics. Based on the model, the effects of stress states and fracture configurations (such as single isolated fracture and two interacting fractures) on damage evolution are examined. It was observed that when the differential stress is aligned (or perpendicular) with the blasting wave, it amplifies (or reduces) the damaging effect of the blasting wave on the rock mass in most instances. The effect of the differential stress on the blasting wave is similar to that of an increase (or reduction) in the amplitude of the blasting wave. When the differential stress exceeds the tensile cracking stress, rock damage sharply escalates due to the generation of a plastic region, regardless of the angle between the blasting wave and differential stress. Meanwhile, a study of two interacting fractures reveals that differences in fracture geometry lead to different stress concentration and shadow zones in the specimen. This changes the location and extent of crack development and ultimately affects the strength of the rock. The findings from our simulations provide critical insights for understanding and characterizing excavation damage zones around underground excavations in fractured crystalline rock obtained by drilling and blasting methods and also provide safety predictions for constructed neighboring structures under dynamic loads.

本研究采用数值模拟来仔细研究预先存在的裂缝和地应力状态对裂缝岩石中爆炸引起的裂缝扩展的影响。通过基于粒子的离散元模型模拟裂隙岩石的地质力学行为，该模型使用基于实际岩石样本（特别是北山花岗岩）的粒度分布的 Voronoi 细分方案构建和组装的粒子，捕获动态下的固体振动载荷并实际响应裂纹扩展和断裂位移。该模型的可靠性也使用斯涅耳定律和断裂力学进行了验证。基于该模型，研究了应力状态和断裂形态（例如单个孤立断裂和两个相互作用断裂）对损伤演化的影响。据观察，当差异应力与爆破波对齐（或垂直）时，在大多数情况下会放大（或减少）爆破波对岩体的破坏作用。应力差对爆破波的影响与爆破波振幅增大（或减小）的影响类似。当差异应力超过拉裂应力时，无论爆破波与差异应力之间的角度如何，由于塑性区域的产生，岩石损伤都会急剧升级。同时，对两个相互作用的裂缝的研究表明，裂缝几何形状的差异导致样本中存在不同的应力集中和阴影区域。这改变了裂纹发展的位置和程度，并最终影响岩石的强度。我们的模拟结果为理解和表征通过钻孔和爆破方法获得的裂隙结晶岩石中的地下开挖周围的开挖损坏区域提供了重要的见解，并为动态载荷下建造的邻近结构提供了安全预测。