Study On Mining Technology Of Cutting Roof And Retaining Roadway Along Goaf Without Coal Pillar In Dongdong Coal Mine

Based on the mining geological conditions of Dongdong Coal Mine and the 50107 working face transportation lane as the research background,this paper uses theoretical analysis,numerical simulation,physical simulation combined with industrial test analysis method to produce coal pillars with different mining height and coal rock strength.The research on the mining system has been carried out,and the structural characteristics of roof overburden failure,the stability of roadway roof,the law of mine pressure,the dynamic instability mechanism of the roadway along the goaf and the practical application of automatic roadway technology for top pressure relief are studied.Analysis,the main research results are as follows:(1)According to the numerical simulation analysis of the roadway along the goaf,the sinking amount of the roof is farther away from the coal wall.As the topping height increases,the amount of roof subsidence decreases.When the cutting height reaches 7m,the amount of roof sinking decreases little with the increase of the cutting height.Therefore,considering construction and simulation analysis,it is determined that the reasonable cutting height is 7m.(2)Through the physical simulation test observation and research,it is concluded that the mining direction of the working face is 10m(the unaffected position of the mining),and the cutting edge is left along the empty roadway.The cutting depth of the roadway is 7.4m and the cutting angle is 20°.Due to the action of the slitting line,the top plate of the upper roadway does not form an obvious cantilever beam structure,thereby reducing the stress effect of the roof plate on the roadway,which is beneficial to the stability of the roadway and is consistent with the numerical simulation results.(3)Through the analysis of the monitoring point data of the 50107 working face layout,the amount of roadway and the top floor of the roadway with.the coal-free column cutting roof is obviously reduced,which shows that the effect of retaining the roadway without the coal pillar cutting roof is obvious.(4)Through observation and analysis of the working surface pressure gauge,the strut pressure gradually increases with the advancement of the working face,and the average force of the strut near the side of the goaf is greater than the average force of the strut near the alley;the strut is stressed.The large area is mainly concentrated within 20m behind the working face,and undergoes obvious pressure relief process.The stability of the single side of the goaf and the central part of the roadway are reduced.Therefore,the effect of cutting the roof to relieve the surrounding rock of the roadway better.