Evaluation Of The Ordovician Limestone Water Enrichment And Water Inrush Risks Of The NO.11 Coal Seam Floor In Baode Coal Mine

Based on the systematical collection and analysis of the previous geological exploration data, the coal exploiting and mining data, the geophysical prospecting data, and the complement hydro-geological exploration data, water enrichment of the Ordovician Limestone aquifer and water inrush risks during the No.11 coal mining were systematically studied in this paper. According to systematical analysis of the drilling data, water pumping tests and releasing tests data, the hydro-geological characteristics of the Ordovician Limestone aquifer were also analyzed from several aspects, such as the lithology, the development of the water-storing structures, water level and its fluctuation, water quality, the characteristics of the water supply, water runoff and water drainage, and so on. Hydro-chemical subsections of Ordovician limestone aquifer were delineated through the hydro-chemical data analysis. Abnormal water abundance regions of Ordovician limestone aquifer were also delineated according to collecting and processing of the ground and underground geophysical prospecting data. The distributions and types of the natural water conducted channels were studied on that basis. According to the position relationship between water conducted channels with the No.11 coal seam floor and with the top interface of Ordovician limestone aquifer, natural water conducted channels were divided into three types:TypeⅠ, TypeⅡ, and TypeⅢ. Relatively threat degrees to the No.11 coal seam floor during mining from every type of channels were separately discussed. Comprehensive evaluation of the water resistance of the coal seam floor aquicludes was done according to the systematical analysis of the floor aquicludes'thickness, litho-logical associations and physical mechanics properties. The specific data of the depth of coal seam floor breaks was obtained by water injection field test. Relative water inrush dangerous zones were compartmentalized by water inrush coefficient. The effect on the water inrush risks from the natural water channels was studied in details in this paper. According to the combination of the natural water channels and water inrush coefficient zones divided, degrees of water inrush risks from Ordovician limestone aquifer were classified into four ranks: Rank A, Rank B, Rank B'and Rank C. At last, corresponding water-inrush preventing and controlling measures were given on that basis.