The Research Of Mine Karst Water Inrush On Conditions Of Water Pressure Mining

Mine inrush as one of the main factors has been restricted the development of Chinese coal industry,with the development of Chinese coal industry,coal mining is faced with more and more serious hydrological problems. Particularly in the eastern and central area of north China coal mine, with the exploitation of Coal resources in the group of the failure, mining-rich coal seam under the group are facing the threat of bottom karst water pressure,it is restricted the sustainable development of coal production and mining areas to a considerable extent. Therefore,study the hydrogeological conditions and inrush conditions of seam floor karst aquifer, take effective method forecasting inrush from coal floor, provide a reliable basis of hydrogeological for mining of coal threatened by karst water,have extremely important significance.In this paper, to the second level(Namely the level of previous mining along the seam tend to extend to depth level) of Xiyu Coal Mine of Taiyuan No. 9 coal mining of water pressure as an example research the inrush of mine karst water , exploitation elevation of the Second level is +650m, the lowest mining level is +430m, but the ordovician karst water pressure water elevation is +803m, maximum water pressure head is 4.3Mpa. Firstly collection of the mine survey and pumping test data, learn more about the geological and hydrogeological conditions of study area. Second, quantitative research the hydrogeological conditions of ordovician karst aquifer,which as major filling with water of the second level coal floor of the Xiyu coal mine with the method of combining chemical thermodynamics of water, chemical kinetics of water with geological, hydrogeological. And then study the conditions of the seam floor karst water inrush ,that is fault structures, collapse columns on the impact of mine water inrush,anti-waterproof performance of No. 9 coal seam floor impermeable layer, the damage depth of the 9th seam floor on the conditions mining etc. Finally, on the basis of these studies, prediction the inrush of the karst water, and predicted the inflow when the mine karst water prominent .The following conclusions can be drawn:1. Based on the calculated results of study area's karst water ion activity and mineral saturation index, divide the study area's ordovician karst water into: all mineral dissolved district-wide(βc≤1); Calcite saturation, and other minerals dissolved district-wide(βc>1,βd≤1); Calcite, dolomite saturation, and other minerals dissolved district-wide(βc>1,βd>1,βg≤1).2. Use the method of groundwater chemical kinetics calculate study area 8 section 92 points water permeability, hydraulic conductivity, seepage velocity and circulation age, and based on the calculated results, according to the size of permeabilit the study area divide into: highly permeable zone, strong permeability zone, permeability strong area, middle zone permeability, permeability of weak areas and very low permeability zone; according to the size of the transmissivity is divided into: highly water conductivity area, strong water conductivity zone, Water conductivity strong area, water conductivity middle zone, water conductivity weak areas and water conductivity very weak area; according to the degree of actual flow and cycle age is divided into: cycle alternating fastest zone, cycle alternating faster zone, cycle alternating fast zone, cycle alternating middle zone, cycle alternating slow zone and cycle alternating very slow zone,3. Analysis the second level faults and karst collapse columns on the impact of water inrush; Calculate the equivalent impervious thickness and the effective impervious thickness of No. 9 coal seam impervious base, the equivalent impervious thickness 25.33m～45.46m, average 35.62m, the effective impervious thickness 22.76m～62.42m,average 39.52m; Calculate the damage depth of No. 9 coal seam base on the conditions of mining, on mining depth 300m, the normal zone damage depth 17.38m, fault-intensive zone damage depth 17.74m, on mining 400m, the normal zone damage depth 18.29m, fault-intensive zone damage depth 18.65m, on mining 500m , the normal zone damage depth 19.20m, fault-intensive zone damage depth 19.56m.4. According to geographical indicators of water inrush coefficient, fractures and water-rich, prediction the karst water inrush of No. 9 coal seam, and divided mining into security areas and relatively safe areas and dangerous areas.5. The assumption that the premise of water inrush occurred, predicted the inflow when the mine karst water prominent,the water inrush when Karst water level transient drawdown 50m is 9831.64m3/d.