Prediction Of Damage Risk Of Roof Water And Floor Ash In Coal Seam 15^-3 Of Miaozhuang Coal Mine

With the continuous exploitation of coal resources in China,shallow coal resources arc gradually depleted,many coal mines have been transferred to deep mining,and the water hazards faced by mines are more complex.Miaozhuang coal mine belongs to North China briquette field.At present,the mining arrangement is concentrated in the deep coal seam of the lower formation.The mining conditions are not only threatened by the high confined water of the bottom slab,but also the danger of water accumulation in the goaf of the coal formation on the roof mining fissure communication.Based on the theory analysis,numerical simulation and machine learning model of coal seam No.15-3 coal seam in Miaozhuang Coal Mine,this paper studies the prediction of coal seam mining fracture development.Based on the view that mining fracture destroys the water barrier,the risk analysis of goaf water accumulation and floor ash confined water damage in No.15-3 coal seam is carried out.The main research contents and achievements are as follows:(1)Based on the analysis of coal seam occurrence,geological structure,water-bearing layer and mining status,the main water source and water-filling channel of No.15'3 coal seam are discussed.(2)A numerical model of coal seam mining is established using FLAC30,The dynamic evolution characteristics of overburden plastic zone,stress and displacement under different propulsion steps are analyzed,Come to the conclusion that when the face advances 320m,The coal seam reaches full mining,The height of overburden fissure zone is stable.Combined with numerical simulation,empirical formula and measured value of adjacent mine mining,Determine 15-3 coal seam water diversion fracture zone height of 95 m,The fracture ratio is about 25.2 per cent.(3)analyzed the main influencing factors of the depth development of the bottom plate damage,conducted the variance analysis,correlation analysis and weight analysis on the measured factors,finally processed the correlation and redundancy of the sample data,and established the bottom plate damage depth prediction model combined with the genetic algorithm.Finally,the bottom plate mining failure depth of 15-3 coal seam and upper group coal mining area are 23.22m and 20.04m respectively.(4)Combined with 15-3 coal seam water-conducting fracture zone height,borehole data and prediction value of mining failure depth of roof mining water-space,Draw the contour map of effective water barrier layer between coal seam 15-3 and roof goaf,It is concluded that mining fissure of coal seam No.15-3 can not communicate the water accumulation in roof goaf;Combined with borehole data,water inrush coefficient method and prediction value of mining failure depth of coal seam floor 15-3,Prediction of water inrush risk of 15-3 coal seam floor,The comprehensive hazard classification zoning prediction map of coal seam floor No.15-3 is drawn.The research results can provide some theoretical basis for the safe production of the mine,At the same time,it can also enrich the research content of safe mining of deep coal seam in the lower formation of China at the present stage..