关键词: 充填开采, 覆岩裂隙, 时空演化, 相似模拟

Abstract: Taking the proposed backfill face of Renjiazhuang Mine as the engineering background, through similar material simulation experiments, this paper statistically analyzes the parameters such as the number, angle, length and width of overburden fractures, and studies the temporal and spatial evolution law and distribution characteristics of overburden fractures in backfill mining. The results show that the excavation and backfill distance of coal seam is short, and the low-level rock stratum near the coal seam first produces transverse fractures, with a small number and a nearly horizontal angle. With the increase of excavation and backfill distance, the number and length of transverse fractures increase. The non penetrating longitudinal fractures derived from transverse fractures are basically distributed in the area at the junction of coal pillar and goaf. Their length is relatively short and the angle is generally greater than 180 °. The overburden fractures gradually develop and expand from low-level rock stratum to high-level rock stratum, and the fracture distribution range gradually expands. The fracture development at the key stratum is hindered to a certain extent. The fractures in the overburden in the middle of the mining and backfill area shrink and close, slowing down the increase in the number of overburden fractures. The fracture width of overburden after stopping mining is generally less than 0.8mm. From both ends of the fracture to the middle, the fracture width first increases and then decreases; The width of overlying rock fracture at the mining starting position is larger than that near the stopping position. Finally, the control factors of overburden fractures in backfill mining are analyzed from the aspects of stope backfill rate, mechanical properties of backfill body, backfill layout, working face parameters, overburden structure and roof lithology. The research results are of great significance for further understanding the development and evolution of water conducting fractures and water retaining mining.