Research on Overburden Breakage Evolution and Surface Damage Characteristics in High-Intensity Mining of Shallow Coal Seams

During high-intensity mining of shallow coal seams, severe overburden movement and surface subsidence can lead to geological hazards like ground fissures. This study investigates these phenomena at a typical working face in the Shendong mining area. Numerical simulations analyze overburden displacement, stress distribution, fracture evolution, breakage characteristics, and surface subsidence under varying mining advance distances. A theoretical model of overburden breakage and surface subsidence was developed, revealing key mechanisms. Results show that overburden breakage and collapse occur in distinct stages. The presence of key strata is essential for maintaining rock layer stability and controlling surface subsidence. Initial roof breakage occurs at 80 meters of mining advance, with periodic intervals of 40–60 meters. Stress distribution evolves in three stages: overall pressure relief, single-peak stress concentration, and double-peak stress concentration. Fractures propagate through the overburden, reaching the key strata and surface. Once key strata fracture, a "voussoir arch" structure suppresses further fracture expansion. The theoretical model and simulations align closely with field data, providing a scientific basis and technical support for controlling subsidence and aiding surface ecological restoration during high-intensity mining.