Study On The Evolution Law Of Overlying Rock Fissures In The Stope With Paste Local Filling

Based on the development of fissures in paste local filling mining,the paper uses physical simulation,numerical calculation and theoretical analysis to analyze the spatial distribution of overlying rock stress in composite filling mining under the interactive influence of multiple factors(different mining heights,different filling amounts,and different burial depths).The research results can provide an important theoretical basis for judging the occurrence conditions of mine water inrush,predicting water inrush,and formulating mine water disaster prevention and control measures;The technology provides an important theoretical basis for the implementation of water conservation mining and enriches the theory of backfill mining.By analyzing the influencing factors of overburden stability in paste partial filling mining,selecting the main influencing factors,and using mechanical analysis based on elastic foundation beam theory,the overlying rock movement mechanics model and overlying rock movement mechanics equation in paste partial filling mining are established.The overlying rock stability criterion is proposed.Taking the 112201 working face of the 2-2 coal seam in Xiaobaodang 11 mining area as the engineering background,through the physical similarity simulation,the stress change and movement law of the overlying rock during the coal seam mining process were analyzed under the conditions of unfilled and 2/3 filled,and then By comparing and analyzing the dynamic development process of the overburden fissures in the working face under different mining conditions,the study determines the expansion and distribution pattern of the overlying fissures during the partial filling and mining of paste.m,compared with the unfilled mining(the vertical fracture height is 150.5 m),the vertical fracture height of the overlying rock decreases by 72.42%,which proves that the partial filling mining with paste can effectively control the development height of the fractures in the overlying rock.Numerical models of different mining heights,filling ratios and burial depths were established by UDEC numerical simulation software.The distribution characteristics of overlying rock displacement field and stress field are analyzed,and the evolution law of overlying rock fissures in the stope filled with paste is studied.When the burial depth and filling ratio of the working face are constant,the mining height is positively correlated with the development height of the overlying fissures,the mining height is negatively correlated with the peak value of the advance support pressure of the coal wall,and the mining height is positively correlated with the subsidence value of the overlying rock;when the working face is buried deep When the mining height and mining height are constant,with the increase of filling ratio,the range of overlying fissures decreases,and the fissures transfer to both sides of the coal wall,forming dominant channels on both sides of the coal wall.When the filling ratio increases,the peak value of the advanced bearing pressure will increase accordingly,but when the filling ratio increases to 100%,the peak value of the bearing pressure decreases because the filling body and the top plate are in contact with each other and exert active support.When the mining height of the working face and the filling ratio are constant,the height of the overlying fissure increases with the increase of the burial depth,but it does not increase infinitely.This is because the space generated by the composite filling mining and the compressibility of the caving rock are fixed.Therefore,with the continuous increase of the buried depth of the working face,the overburden fissures will gradually tend to a stable value,and will no longer increase with the increase of the buried depth of the working face.