Occurrence regularity of uppermost minable coal seams and their harmful level of mining in Yushen mining area

In order to study the occurrence regularity of uppermost mining coal seams and the damage degree of Salawusu Formation aquifer caused by mining in Yushen mining area, occurrence characteristics of the uppermost mining coal seams was analyzed, and spatial distribution law and combination of the uppermost mining coal seams overlying strata, the development law of the water flowing fractured zone based on the ratio of rock and loading thickness and mining height, and the damage degree of the Salawusu Formation aquifer caused by coal seam mining. The damage degree of the Salawusu Formation aquifer was divided into four kinds of damage degree zones:natural water-retaining zone, water-retaining mining zone(influencing large zone and influencing small zone), water-losing mining zone and coal mining waterless zone. The results showed that the uppermost mining coal seams outcrops in Yushen mining area were stepwise distributed from SE to NW, and the overlying bedrock residual gradually thinned from NW to SE, and the thinning tends to be the opposite of the strata dip direction. According to the research, it was concluded that the mining uppermost mining coal seams in the western part of the Yushen mining area(the third and fourth phase planning areas) had little or no impact on the Salawusu Formation aquifer; the eastern part of the Yushen mining area(the first and second phase planning areas) had high damage by upper-most coal seam mining.