Energy evolution and fractal characteristics of overlying rock fracture under different advancing distances

Intensive coal extraction in western China is severely constrained by overburden instability and subsequent surface damage, posing significant challenges to safe, efficient, and sustainable mining. This study investigates the energy evolution and fractal characteristics of overburden fractures in shallow-buried, weakly cemented strata by integrating physical modeling and numerical simulation based on the Daliuta Coal Mine. Our results show that the interplay between stored elastic energy and dissipated energy governs failure intensity and fracture morphology. Quantitatively, the fractal dimension of the overburden fracture network increases from 1.9939 at an advance distance of 60 m to 1.9943 at 100 m, with a critical threshold of approximately 1.9940 marking the onset of accelerated fracture propagation. This threshold corresponds well with the rapid rise in the height of the water-conducting fractured zone, confirming a strong nonlinear positive correlation between the two. These quantitative insights demonstrate that fractal dimension serves as a reliable indicator for real-time assessment of fracture propagation and overburden stability. The proposed fractal-dimension-based monitoring approach provides a scientific basis for optimizing water-preservation mining, designing roof control strategies, and supporting ecological restoration in similar geological environments.