Fracture Mechanism and Energy Dissipation Characteristics of Coal‐Rock Composite Anchored Body With Through‐Going Joints

ABSTRACT Based on uniaxial and triaxial compression tests of coal and sandstone, deformation and strength parameters for the coal‐rock‐bolt composite structure were determined, providing key inputs for subsequent single free‐surface loading simulation. A numerical model characterizing coal‐rock composite anchored body with through‐going joints was developed using FLAC 3D 9.0 integrated with Fish scripting language. By developing a real‐time energy density tracking program, multi‐factor coupled simulation loading experiments were systematically conducted. The simulations reveal the strength parameter degradation and energy evolution law of the anchored bodies of the coal‐rock composite with through‐going joints. Results indicate that the ultimate strength of the coal‐rock combination depends on the coal mass, the plastic deformation capacity relies more on the rock mass, with the overall stiffness exhibiting intermediate characteristics between coal and rock. Both peak strength and energy storage limits demonstrate positive correlations with interfacial roughness. Furthermore, for the composite geological bodies formed by coal and rock, anchoring reinforcement applied to weaker zones effectively coordinates stress and energy distribution within the composite structure, suppressing localized damage propagation, thereby increasing the energy storage threshold and delaying the catastrophic failure time of the anchored body. Therefore, a “weakness‐compensation‐first” support strategy is proposed to enhance the overall geomechanical performance of the composite structure.