Roof Self Stability Model And Its Engineering Application For Precise Control Of Strata In Backfill Mining

The 5th coal backfilling mining in Tangshan Mine is underground mining.Controlling the surface subsidence and protecting the ground structures above the filling mining area is the primary problem to be solved in this filling mining.This paper designs 5 coal filling mining based on the mining geological conditions of the5 th coal mining in Tangshan Mine.Scheme,and through the establishment of mechanical models and numerical simulations,the connotation of the precise control of the rock fill and the roof self-stability mechanical model,critical conditions and roof stress characteristics are studied.The main research results of the thesis are as follows:(1)According to the migration law of rock strata in backfill mining,the connotation of precise control of rock strata and the roof self-stability model are put forward,and the influence factors of roof self-stability are analyzed.Accurate control of rock strata is based on different engineering backgrounds to accurately control the overlying strata of the filling stope at a critical state that can just meet the engineering needs;in terms of precise rock strata control in Tangshan Mine,roof breakage is the critical condition for filling mining.The roof self-stability mechanical model is used to solve the critical fullness rate required for roof self-stability under different mining conditions.(2)According to the geological conditions of No.5 coal seam in Tangshan coal mine,the reasonable filling scheme is formulated,and the critical conditions of roof self stability under different mining schemes are analyzed.Under different mining schemes,the critical filling rate of roof self stability is mainly affected by the strike footage of working face,the dip size of mining area,the size of coal pillar and the mining sequence of filling face.Under different influencing factors,when the roof reaches self stability,the variation characteristics of filling rate are different.The basic characteristics of filling rate variation are as follows: in a certain mining area,The whole filling rate is only related to the range and size of mining area,and the change of mining sequence has no effect on the whole filling rate.(3)This paper studies the roof stress characteristics of each filling face during mining under different filling schemes,and puts forward the roof self stability guarantee method.Through numerical simulation,it can be seen that under each mining scheme,in the process of filling face mining,the roof stress state is affected by the mining sequence of filling face,the size of working face,the reserved size of coal pillar and other factors,and the variation law of roof stress is not the same,so there are some differences in the roof self stability guarantee methods,but the skip mining and sequential filling mining scheme after the working face is fully mined,The roof stress trend is basically the same.(4)The roof and surface of No.5 coal filling mining area in Tangshan mine were monitored,and the roof movement and surface deformation laws were obtained.The monitoring results of filling mining area show that the average displacement of each measuring point in F5002 working face is 43 mm,the final stable height of filling body in working face is 1.97 m,the filling rate is 82.1%,the average stress of working face is 1.8MPa,the maximum stress is not more than 2MPa,the maximum surface subsidence is 47 mm,and the surface deformation meets the protection level requirements of surface structures.The paper includes 82 Figures,10 Tables and 85 References.