Risk assessment of water inrush of No.11 coal seam floor in Hancheng mining area on the basis of vulnerability index method

Based on the comprehensive analysis of the geological and hydrogeological conditions of the study area (Hancheng mining area), this paper puts forward the index system of water inrush from Ordovician limestone aquifer in the coal seam floor by using the relevant factor analysis method. Taking several typical coal mines as examples, the factors influencing water inrush from the No.11 coal seam floor the most threatened by the Ordovician limestone aquifer, are analyzed emphatically. Four evaluation indexes, which are the effective thickness of the confining bed, the scale of fold, the water content of the aquifer, and the scale of the fault, are constructed. The water inrush risk zoning map of the No.11 coal seam floor is obtained based on the vulnerability index method.