Shallow Overburden Rock Fracture Zone Development Law Under Many Mining Conditions

Taking the shallow buried coal seam in Gaojialiang Coal Mine as the background, the effect of interlayer spacing of close distance coal seams, the mining height of lower coal and strength of bay level on the development height of water following fractured zone were studied by using FLAC^3D. The results show that when the spacing of layers is more than 10 m, the strata development maximum height of fractured zone is mainly affected by the upper coal mining; opposite, the development height is affected by lower coal mining obviously; the water following fractured zone are smaller when the lower coal's height within 5 m; contrary, it increases quickly; the water fractured zone height increases with the increasing of spacer layer of rock strength. The grey correlation analysis shows that the factors influencing the following fractured zone height are mining heights, the strength of bay level, the interlayer spacing of close distance coal seams in turn.