Risk Assessment Of Water Inrush From Floor Of No.11 Coal Seam In Hancheng Mining Area

Mining of lower coal seam has been limited by the threat of Karst fissure confined water in Ordovician limestone aquifer in North China coal field.Because of the large amount of water,high water pressure and uneven distribution,mine water bursts occur frequently.The Hancheng Mining of No.11 coal seam in mining area also facing the threat of Ordovician limestone water.While the Hancheng mining area is rather special that aults and folds are developed,secondary cracks criss-cross.It provides a good space and water channel for Ordovician limestone water,11 coal mining in the area is facing greater risk.In order to ensure the safe production of mining area,by collecting the existing geological and hydrogeological data in Hancheng mining area.We further find out the hydrogeological conditions in the area,analyze the law of karst development and the supplement and drainage conditions of Ordovician limestone water.By using the method of "rich water index",and the water abundance of Ordovician limestone aquifer is obtained.Based on the hydrochemical characteristics of Ordovician limestone water in the mining area,we studied the groundwater flow field of Ordovician limestone water.In this paper we use Flac3D software to simulate the mining,and find the failure depth of the coal seam floor of No.11 coal seam in the mining area is 12?16m.Based on the situation of mine water inrush,we evaluated the influence factors of mine water inrush and analyzed the influence of the factors such as unit water inflow,permeability coefficient,thickness of water layer,fold structure and fault structure on water inrush from floor.Use the analytic hierarchy process to calculate the weight of the factors affecting the water inrush from the floor and we also use Arcgis software to analyze the results.Finally we obtain the influence factors of mine water inrush,divide the risk region of No.11 coal seam mining.The results show that the danger zone of water inrush is belong to the structure development of southeast shallow mining area and The deep area of Southern Mining Area.This law is consistent with the water inrush from the Ordovician limestone floor.The research result has certain guiding significance to the safety mining of No.11 coal seam in the area.