关键词: 浅埋煤层, 采高, 推进距离, UDEC, 数值模拟, 地表沉陷

Abstract: Aiming at the problem of surface subsidence mutation caused by shallow coal seam mining in thin bedrock，taking 3504 working face of a mine in Datong City，Shanxi Province as the engineering background，the dynamic response mechanism of overburden fracture evolution and surface movement and deformation under the synergistic effect of mining height and advancing distance is systematically revealed by combining theoretical analysis，numerical simulation and engineering verification. Through the UDEC discrete element numerical simulation software，the geological model of thin bedrock and thick loose layer is constructed，and the law of overburden fracture and surface movement and deformation under the syner⁃ gistic effect of different mining height and advancing distance is studied. The results show that the synergis⁃ tic effect of mining height and advancing distance significantly affects the stage characteristics of surface subsidence. When the mining height increases from 2.8 m to 6.8 m，the maximum roof subsidence increas⁃ es non-linearly by 106.5%~202.3%，and the corresponding surface subsidence increases sharply from 50 mm to more than 200 mm. When the mining height exceeds 4.8 m，the supporting effect of roof expansion is weakened，and the fracture penetration and caving height increase significantly，resulting in the acceler⁃ ation of surface subsidence rate. The study further shows that when the advancing distance reaches 80 m， the overburden failure enters the unstable stage，and the surface subsidence increases sharply. When the mining height is more than 4.8 m，the surface subsidence exceeds the safety threshold after advancing to 100 m. It is suggested that measures such as optimizing mining height (below 4.8 m)，adopting segmented support technology or dynamic adjustment of advancing distance should be taken to inhibit fracture penetra⁃ tion and overburden instability and reduce the risk of surface sudden subsidence.

Key words: shallow coal seam, mining height, advancing distance, UDEC, numerical simulation, surface subsidence