Overburden Damage in High-Intensity Mining: Effects of Lithology and Formation Structure

This study addresses pivotal scientific questions regarding the evolution of overburden strata during high-intensity mining in the Shendong coal mining area. Through a comprehensive research methodology combining physical similarity tests and numerical simulations, we systematically quantified the influence of key stratum thickness, key stratum location, and mining thickness on overburden damage and fracture propagation dynamics. The results reveal that: (1) The fractal dimension of the fracture network in the damaged overburden ranges from 1.2 to 1.5; a reduction in the thickness of the key layer results in the most severe overburden damage, whereas a decrease in mining height leads to the least damage. (2) A reduction in key stratum thickness accelerates structural failure initiation, expanding rock subsidence area (16.7% increase) while constraining fracture zone vertical development (8.3% reduction). (3) Raising the key stratum position demonstrates dual suppression effects, decreasing both subsidence magnitude (22.4%) and spatial extent (18.6%) of overburden movement. (4) Conversely, a decrease in mining thickness induces the amplified subsidence responses (20% increase), accompanied by enhanced fracture zone vertical propagation. This study provides an important reference for the systematic investigation and comparison of the impacts and prevention strategies associated with high-intensity mining in the Shendong mining area.