Energy Dissipation Behavior and Fracture Evolution Characteristics of Damaged Coal Under Cyclic Loading

ABSTRACT Understanding the failure of damaged coal under mining‐induced disturbances is critical for safe resource extraction. Therefore, coal specimens with varying initial damage degrees were subjected to frequency‐increasing multilevel cyclic loading. Mechanical response, energy partitioning, and damping ratio were evaluated, and postfailure fracture networks were quantified by computed tomography (CT) and fragment‐size fractal analysis. Increasing initial damage led to systematic reductions in peak strength, elastic modulus, and a higher dissipated energy proportion (up to 2.888%), indicating accelerated damage accumulation and earlier instability. CT and fragmentation results showed higher fracture volume proportion (up to 11.356%), larger fractal dimensions, and more fine fragments. These findings demonstrate that frequency‐increasing multilevel cyclic loading acting on damaged coal promotes the formation of a dense fracture network, which severely weakens elastic energy storage and amplifies irreversible energy dissipation. Moreover, the proposed energy‐fracture multiscale framework clarifies how initial damage controls coal failure under cyclic loading.