Study On The Technical Research Of Cutting And Unloading The Roof Pressure To Optimization Design Of Entry Protection District Dip Coal Pillar

For a long time,the protective coal pillar is the main way to protect the roadway,so the width and stability of the protective coal pillar are of great significance to the maintenance of system roadway and the safe and efficient production of coal mine.Therefore,this paper takes the 17191(1)working face of Pansan Coal Mine as the engineering background,and studies the optimization of the width of the protective coal pillar under the roof cutting and unloading technology by theoretical research,similarity simulation experiment and numerical simulation experiment.The main research contents are as follows:(1)The influence of the width of down-hill protective coal pillar on the structure and movement of overburden rock and the stress evolution of surrounding rock in down-hill system during the conventional mining of 17191(1)working face is analyzed.As the width of coal pillar decreases,the influence range of mining stress moves forward along the advancing direction,and the vertical stress of surrounding rock increases gradually.The width of coal pillar when the influence range of mining stress spreads to the roadway and the position of stoping line proposed to adopt blasting cutting pressure relief technology are defined.(2)Based on the critical stratum theory,it is clear that thick and hard "rock beam"of the roof is the channel through which mining stress is transmitted to the system roadway,and the target stratum of blasting cutting roof of the overburden strata on the 17191(1)working face of Pansan Coal Mine is determined.Combined with the cantilever beam theory to analyze the roof structure characteristics,it is clear that the roof pressure relief technology can reduce the length of the cantilever beam,improve the stability of the cantilever structure,reduce the load in coal and rock before work,improve the system tunnel stress environment,and verify the feasibility of the roof pressure relief technology.(3)The paper analyzes the migration of overburden rock and the stress variation of surrounding rock of roadway by the width of coal pillar when the working face is 190m away from the down-hill roadway.After cutting the roof,the breakage degree of the roof is intensified,the cantilever length is shorter,the stress concentration degree of the overburden strata in front of the coal wall of the working face is reduced compared with the conventional mining,the stress environment around the system roadway is improved,and the width of the coal pillar is optimized reasonably.Based on the above research,taking pansan Coal Mine 17191(1)working face and downhill system roadway as engineering background,a top cutting pressure relief technical scheme is proposed.The engineering application shows that the effect of roadway protection is good and the overall deformation of surrounding rock is small.By cutting top pressure relief technology to optimize the width of coal pillar for the following production operation to provide security and improve the coal recovery rate and economic benefits.Figure[51]Table[15]Reference[91]...