Characteristics Of High-pressure Karst Water And Prediction Of Water Inrush In Deep Mining

As the years of coal mining goes on in our country,shallow mineral resources have increasingly dried up,so coal resource mining in deep-lying have and will become inevitable tendency.However,geological conditions become more and more complex,and water pressure,ground pressure stress and geothermal temperature also increase,which results in sudden accidents more likely.North China coal field is important coal base,where mining coal seam is in carboniferous Permian coal group,and coal measures strata is covered in thick Cenozoic formation.Its huge thick carbonate formation,pore,fracture and solution pores development capability are strong,with high water pressure high water rich,so water inrush accidents occurred repeatedly backplane limestone karstic fissure aquifer.With the increase of mining depth,bottom limestone karstic fissure aquifer water get more complex,combined with the complexity of geological structure conditions,hydrogeology characteristics of limestone aquifer and water inrush risk prediction need to be solved urgently in deep mining safely.Suntuan coalmine is located in the southern margin of North China coal field.Its hydrological geological environment has the basic characteristics of the north China coal field.During pre-production stage,water bursting accidents was taken place in the first limestone mining 1028 working face floor.Based on Suntuan coalmine as an example,the paper focuses on two aspects:characteristics of high-pressure karst water and waterproof prediction of deep coal seam.The study of water-rich characteristics is the basic work to explore the mechanism of water inrush from coal floor.The study of water-rich characteristics was carried out from five aspects:situation Analysis during Deep Coal Seam Mining,characteristics of karst lithologic,characteristics of Karst fracture,hydraulic characteristics in aquifer from deep coal floor,and characteristics of the water rich deep karst fissures.Results show that the water richness of the deep aquifer in Suntuan Coalmine area is between the weak water-rich and the medium-rich water,with the unit water inflow basically below 1.0L/S.m.Water inrush of coal seam floor was studied,Mainly including by three aspects:the watertight performance of coal seam floor,the stress and strain variation of bottom plate in coal seam mining and gray fuzzy mathematics method by which to analyze the risk of coal seam floor.Results indicate that the water pressure in most areas of the bottom of the study area is lower than the compressive capacity of the coal floor,so the water barrier performance of the aquifer is better.Through the formula combined with FLAC3D numerical simulation,it is concluded that the maximum failure depth of the aquifer in the Suntuan Coalmine area is about 14m.On the basis of previous research,the appropriate influencing factors were selected to divide the deep dikes into four areas by the risk of water bursting.The about 50%of the entire mining area are the safe and relatively safe area,and the rest are the threat area and dangerous areas.