Study on the influence of limestone aquifer on the mining No.13 coal seam in Qianbei coalfield

No.9 coal seam in Jinsha area of Qianbei coalfield is an outburst coal seam. In order to liberate the outburst coal seam, it is necessary to first mine No.13 coal seam as the liberated layer of No.9 coal seam. However, No.13 coal seam in Jinsha area is close to the Maokou limestone aquifer in the floor, and there is a danger of water bursting in mining No.13 coal seam. Taking a research area in Jinsha area as the research object, the data of lithology, thickness of aquifuge and top boundary height of limestone in Maokou Formation of 38 boreholes were analyzed statistically. It is found that there are 9 kinds of rock strata with good water resisting property in the lithology of the aquifuge in the floor of No.13 coal seam, and the cumulative thickness of the strata accounts for 43.51% to 100.00% of the thickness of the aquifuge, with an average of 75.56%. The lithology of the aquifuge has the characteristics that the upper and lower layers are relatively soft, the middle layers are relatively hard, and the water resisting performance is good. The thickness of the aquifuge in the floor of No.13 coal seam ranges from 13.53 m to 35.15 m, with an average of 19.48 m. The water head value of the Maokou Formation limestone aquifer ranges from 1.35 MPa to 5.57 MPa, with an average of 3.33 MPa. The thickness of aquifuge of driving working face can meet the requirements. During the mining of No.13 coal working face, 97.38% of the area is in a dangerous area. It is recommended not to be mined until water control measures are taken. The research results can provide reference for the prevention and control of water damage of No.13 coal seam and floor in Jinsha area in Qianbei.