Development Law Of Water Flowing Fractured Zone In Overlying Strata In Mining Near Loose Aquifer In Dingji Coal Mine

When the loose aquifer is mined,the overburden strata of the coal seam will be affected by the mining and the rupture deformation will form a water conducting fractured zone,thus communicating the water inrush of the roof in the upper aquifer.At present,Dingji Coal Mine of Huainan Coalfield has not done research work on water conducting fracture zone in recent years.Therefore,by studying the development law of its water conducting fracture zone,it will reduce the waterproofing coal column,release the stagnant coal volume to improve the economic benefits of mine production has good theoretical significance and application value.In this paper,the 1121?3?working face of the east NO.1 mining area of Dingji Coal Mine in Huainan Coalfield coalfield is studied.On the basis of analyzing the spatial occurrence regularity of the aquifers and aquicludes of Cenozoic and the geological characteristics of the overlying strata in the study area.The indoor rock physical and mechanical tests,similar material test simulations,numerical simulations and empirical formula calculations were used to study the development law of the water-conducting fracture zone of the overburden coal seam in the near-loose aquifer.Finally,the rationality of the research on the development of the fracture zone is verified.?1?The thickness of Cenozoic loose beds in east NO.1 mining area ranges from499.2 m to 553.2 m,and the variation trend of thickness increases gradually from southeast to northwest.The water inflow per unit is 0.21 to 0.30L/?s·m?,and the water-rich is medium.?2?The development law of the water-conducting fissure zone of the overlying strata in the 1121?3?working face is studied by the similar material simulation method.With the increase of excavation distance,the height of fissure zone increased gradually until the height of water conducting fracture zone reached its maximum when it was stable at 43 m.?3?The FLAC^3D numerical calculation method is used to simulate the variation of stress field,displacement field and plastic zone of coal seam roof under different propulsion distances.The numerical simulation results show that the development height of overburden water-fracture fissure zone of near-loose aquifer is 40.8m.Based on this simulation,the development height of the water-conducting fracture zone decreases with the increase of the propulsion speed within a certain propulsion speed range.Within a certain range of loose layer thickness,the development height of the water conducting fracture zone increases with the increase of the thickness of the overlying Cenozoic loose layer.?4?In order to verify the rationality of similar simulation and numerical simulation results,the height of the overburden fracture zone is 40m by the method of geophysical survey,which is basically consistent with the simulation results.?5?Based on the results of simulation,detection and theoretical calculation,the height conduction range of 1121?3?working face in east NO.1 mining area is determined to be 40-42m,and 42m is taken as the recommended value of predicted height of water conduction fracture zone,with the fracture-production ratio of 11.35.Figure[45]table[16]reference[102].