Study On Overlying Strata And Surface Subsidence In Thick Coal Seam Mining In Barapukuria Mine

For thick coal seam mining,the mining space is greatly increased,the movement range of mining overlying strata is increased,the overburden and ground subsidence rules caused by coal seam mining have its particularity under normal conditions.This paper takes Mengba mine as the research object,Combining the measured data from five surface observing stations with the developmental height data of the drilled fracture measured above the 1210 working face,the rules and particularities of the overlying strata and surface movement deformation caused by the mining of thick coal seams are analyzed and studied.The factors affecting the rules of surface movement deformation and overburden failure are studied through theoretical analysis and numerical simulation methods.The main results obtained are as follows:(1)Through processing and analying the measured data from the surface observation stations at the 5 working faces of the Mengba mine,the characteristics of the curve reflecting the surface,the values of the surface movement angles at each working face and the expected parameters of the probability integration method under the specific geological mining conditions of the Mengba mine are obtained.(2)With the help of UDEC numerical simulation experiments,the surface subsidence law that changes with the increase of mining thickness is simulated,and the relationship between subsidence coefficient are obtained.Stratified mining involves repeated mining,in the question,the law of surface subsidence caused by the different positions of the mining face and old goaf are simulated from the horizontal and vertical directions.(3)With the help of numerical simulations,the effects of the size of the mining length and the different mining thicknesses on the damage development height of the overlying strata are studied.Combined with the measured data and numerical simulation results of the water-guiding cracks in the Mengba,the results are fitted.The empirical formula for calculating the development height of the water-guiding fracture zone under stratified mining conditions provides a basis for the safe mining under the water body of Mengba Mine.(4)The mining subsidence prediction software is used to predict the surface deformation of the entire mining areas after the first,second,third,and fourth stratified mining of the Mengba mine,and the thickness of safe coal mining under the thick aquifer is determined.