Research On Overburden Migration Law Of Paste Backfilling And Slicing Mining In Thick Seam

With the increasing of the "three under" pressure coal,in order to solve the problem of three under pressure coal,improve coal mining efficiency,solve the problems of overlying rock movement and surface subsidence during coal mining.Based on the backfill mining of No.3 coal seam in Gaohe Mine,using comparative analysis,theoretical analysis,numerical simulation,similar physical simulation experiment and other methods to study the movement of overburden and the law of surface deformation in the process of paste backfill stratification and co-mining.This paper mainly obtains the following research outcome:(1)The rock mechanics parameters were tested in the laboratory to obtain the physical mechanics parameters of coal(rock),and using comparative analysis determine that the E1306 coal face adopts paste backfill and layering simultaneous mining technology,downward mining,upper mining and lower backfill,and the roadway layout of the working face.(2)By using the numerical simulation method,analyzing from two aspects of stress and displacement,when the paste backfilling stratification and co-mining distance is 80 m,the subsidence of the roof rock beam and the peak value of the advanced supporting pressure are the smallest;Using similar physical simulation experiment methods,during the experiment,the roof rock beam will only show the overall bending subsidence and crack expansion without breaking.When the stratification distance is 80 m,the roof rock beam subsidence and the peak value of the advanced supporting pressure are the smallest,which was corresponding to the numerical simulation results.(3)Establish the mechanical model of the elastic foundation beam for paste backfilling mining,derive the deflection curve equation and the vertical stress equation of the roof rock beam subsidence,analyze the depth of the coal seam,the elastic foundation beam coefficient of the filling body,the thickness of the direct roof beam and the direct roof elastic modulus affects subsidence and vertical stress of the roof rock beam.And deduced the functional expression of the roof rock girder subsidence and the maximum ground subsidence.(4)By using the numerical simulation method,analyze the influence of different burial depths and elastic modulus of the filling body on overburden migration law of the paste backfilling stratification and co-mining,when the filling body strength is 4.88 MPa,it can be realize the deformation and destruction of the ground surface within the scope of class I damage.(5)Establish the equivalent mining height mathematical model for paste backfill mining to determine the composition factors of the ground subsidence,according to the probability integral method,it is estimated that the final ground subsidence of E1306 working face is estimated to be 520 mm,the tilt deformation is 1.4 mm/m,and the horizontal deformation is 1.06 mm/m.The deformation and damage of the ground surface are within the national level I damage range,which does not exceed the fortification standard.There are 73 figures,11 tables and 84 references in this paper.