Inrush Risk Assessment And Control Measures Of Groundwater In Deep Mining Of Xinzheng Coal Power Company

The study area,where is a deep unexploited area with 10 km2,is located in the west of Xinzheng Coal Power Compay.The main aquifer is limestone of Taiyuan Formation with high water pressure and thin effective aquifuge.The mian ?1 coal seam is threatened by water inrush and is easy to suffer from water inrush accident.Therefore,the risk of water inrush from coal seam floor is assessed and L1-4 limestone water drainage schemes are designed through the analysis of the geological data,hydrogeological data,seismic exploration and transient electromagnetic data.The main research methods in this thesis are AHP level analysis,fractal theory,numerical simulation,vulnerability index method and so on.The conclusions are as following:Water abundance of limestone aquifer is moderate in the study area.RQD is about 78.9%~99%.The rock mass is better and no large fissure is found.By using the fractal theory,the complexity of coal seam floor structure is simple.By using “steady flow method” and “hydrogeological analogy method”,the normal amount of water inflow is estimated,which is 1280 m3/h and 2158 m3/h respectively.Maximum amount of water inflow is 2022 m3/h and 3410 m3/h respectively.The water inrush risk of L1-4 limestone is analyzed emphatically in the study area.Firstly,the main control factors are obtained by fractal theory,transient electromagnetic,3D seismic exploration and so on.Then,a vulnerability assessment model,based on SURFER and AHP,is established to evaluate the risk of water inrush from ?1 coal seam floor.The five type distrcts for the floor are divided,which are danger zone,relative danger zone,transition zone,relative safe zone and safe zone,respectively.With the increase of the buried depth of the coal seam,the risk of water inrush from the ?1 coal seam floor is gradually increasing.On the basis of the risk assessment of water inrush,the drainage and the depressurizing project from L1-4 limestone water is analysed and desgined.Furthermore,the drainage effect of L1-4 limestone water is simulated by Visual Modflow software.When maximum single well pumping rate is 1440 m3/d,five pumping wells are designed to realize water drawdown from 349 to 511 m within 50 to 200 days,which can meet the purpose of reducing the pressure of limestone water.At the same time,it is concluded that water level from L1-4 limestone is decreasing at different areas with pumping times.