Investigating the Interacting Mechanisms of Precast Intersecting Cracks in Concrete: Insights from the Simulations Based on Discrete Element Method

Underground mines often use shotcrete and reinforced concrete as support. Excavation disturbance, in situ stress, and blasting cause initial fractures to propagate. Intersecting fractures are common. This paper studies how intersecting fracture geometry affects fracture propagation under uniaxial compression. DEM and Particle Flow Code (PFC2D, Particle Flow Code) are used to build mesoscopic models with single-intersecting fractures (30–150°) and double-intersecting fractures with five offset levels: Zero, Minor, Moderate, Substantial, and Maximum. For single-intersecting fractures, smaller angles cause stronger shear slip and more multi-source cracking. Peak stress, ultimate strain, and final crack number (defined as the sum of tensile and shear micro-cracks from parallel-bond failure) increase. Larger angles lead to brittle failure and weaker properties. For double-intersecting fractures, bearing capacity first increases then stabilizes with offset. Zero and Minor offset have lower strength; Moderate, Substantial, and Maximum offset have higher capacity. Crack number increases with offset. Maximum offset has the most cracks but the smallest ultimate strain, while Substantial offset has the largest, with deformation from shear slip and higher brittle failure risk. Double-intersecting fracture specimens have fewer cracks but more concentrated damage and weaker properties than single-fracture specimens. This indicates damage distribution, not crack number, governs degradation. This study reveals how fracture configuration controls concrete response, providing mechanistic references for understanding failure behaviors related to safety-analysis and reinforcement-oriented research.