Study On Prevention And Control Technology Of Mining Water In No.3 Coal Seam In Water Accumulation Area Of Jiaojiagou Coal Mine

Aiming at the problem that there are many goafs in No.5 coal seam of Jiaojiagou Coal Mine after the old kiln is mined and there is water accumulation in the goaf,this paper analyses the feasibility of safe mining of No.3 coal seam under the water accumulation area of Jiaojiagou Coal Mine,prevents the occurrence of water disaster accidents in No.3 coal seam of Jiaojiagou Coal Mine,and ensures the safe production of the mine.Based on the analysis of the degree of water accumulation and the condition of water replenishment in the old mining area of No.5 coal mine,the deformation and failure law of surrounding rock and the development height of water-conducting fracture zone in the longwall fully mechanized mining process of No.3 coal seam at 35-40m below the water accumulation area of Laoyao coal mine are studied by means of numerical simulation experiment,and the necessity of preventing and controlling water in working face and adopting corresponding engineering measures is analyzed.The main water-filling source of No.3 coal in Jiaojiagou Coal Mine is goaf water and unknown old kiln water which may exist in No.5 coal mine.Water-filling channel is vertical water-conducting fracture zone formed by coal seam mining.The first weighting step of main roof in No.3 coal seam wall mining is about 55 meters.In the six periodic weighting,the weighting steps are 20m,20m,20m,12m,16m and 24m,with an average of 18.7m;the simulated mining height of No.3 coal seam is 1.2m,and the subsidence coefficient q is 0.623;the height of water-conducting fracture zone calculated by empirical formula is 22m and 21.7m;and the height of water-conducting fracture zone determined by similar simulation is 15.5m.When No.3 coal seam is pushed to 140 m,the roof rock behind the coal wall produces a vertical crack along the caving angle,which is connected with No.5 and No.3 coal seam goaf due to the tension and shear failure of the rock seam.However,with the follow-up advance of the working face,the vertical crack tends to close gradually.When the coal pillar is retained to resist the lateral hydrostatic pressure in the adjacent goaf,in order to ensure that the maximum height of the water-conducting cracks on both sides cannot intersect or penetrate,the width of the coal pillar between the two working faces is 15.4m without draining the water in the adjacent goaf area,and the width of the coal pillar is 10.4m in the case of draining the goaf water.After each working face is mined,the connecting roadway should be sealed with waterproof wall.The specification of waterproof wall is 5 m x 3.5 m x 2.3 M.Plastic steel pipe should be embedded on the wall and water control valve should be installed so as to reduce pressure in goaf water in time and provide industrial water for adjacent working face.Construction should strictly comply with the design requirements and the engineering practice effect is good.