Development regularity and influencing factors of overburden fractures in shallow-buried close-distance coal seam mining
Through the collected statistical examples of shallow-buried close-distance coal seam mining,the development regularity of the overburden fractures and their influencing factors in the repeated mining of the top single seams and the lower seams were investiga-ted.It is found that in single coal seam mining,the ratio of fracture development height to mining height is 8.61～32.5,mainly be-tween 15～30.It is positively correlated with the mining height of coal seam.After repeated mining in the lower seam and complete breakage of the interval strata,the activation and development of fractures are more intense in the upper coal seam.Compared with that in the single coal seam mining,the ratio of fracture development height to mining height is reduced.The development height of over-burden fractures is not significantly affected by the buried depth,and mainly increases with the increase of the comprehensive mining thickness of the two coal seams.In addition,with the increase of the mining height,the development height of overburden fractures in-creases at a decreasing rate.
NETL
NSTL
万方数据
