Recearch On Feasibility Of Upward Mining And Reasonable Location Of Roadway In Yongning Coal Mine

In the past few years,our economy has made a great progress.As a main energy source in our country,coal accounts for more than 65% of non-renewable energy structure,and it will play an important role for a long time in the future.Yongning Coal Mine is a integrated mine in Lvliang of Shanxi Province.In the past,it was not found that there is relatively stable coal seam above the 4# coal seam because of the geology exploration.Now,there is a stable coal seam and it can arrange working faces.Because of the impact of mine in 4# coal seam,the part of rocks had been dameged in coal seams.And it is goaf under 3# coal seam,the position of roadway will be influenced due to the 4# coal seam,so it is an issure that setting up a right relationship of working faces of close coal seams.This article will research the feasibility of upward mining and the reasonable position of working faces in close coal seams by the methods including theoretical analysis,numerical simulation and field practice.The specific results including:(1)This article analyzed the construction of rock formation in close coal seams.The construction of rock formation was divided into three sorts,including non-critical layer structure,the single key stratum structure and the several key stratum structure.According to the physico-mechanical characteristics of rock formation in close coal seams,the load and breaking rules of each rock layer in the close coal seam of Yongning Coal Mine are calculated,and the 8th layer sandy mudstone of the 4# coal seam roof of Yongning Coal Mine is determined as thekey layer,namely Yongning Coal Mine.The coal seam is a single sub-critical layer structure between the layers.Based on this,three theoretical methods of“three-band” discriminant method,surrounding rock balance discriminant method and ratio discriminant method are used to determine that the coal mining layer of the 3# coal seam of Yongning Coal Industry can adopt the upward mining method.(2)Through FLAC3 D three-dimensional numerical simulation software,the influence of different working face lengths of 4# coal seam in Yongning Coal Industry on the 3# coal seam was analyzed.The research results show that after 4#coal mining,it will affect the local position of 3# coal,but it does not penetrate the entire coal seam.The coal seam still has a certain continuity,so it is determined that the 3# coal can adopt the upward mining method.(3)Using theoretical analysis and on-site measurement methods,the characteristics of interlayer rock strata and fracture development after coal mining in the near-coal coal seam of Yongning Coal Industry were studied,and the relationship between layer spacing and the sub-coal fissure zone was studied.Classification,and based on the results of on-site peeping,it is determined that the coal seam relationship between the upper and lower groups of Yongning Coal Mine belongs to the second category,that is,the coal seam in the 3# coal seam is located in the general fault zone within the fracture zone of the 4# coal seam,and the location of the roadway in the mining face should avoid the fracture development zone and Stress increase zone.(4)Through the numerical simulation analysis method,the stress concentration area in the coal seam of the 3# coal seam after the 4# coal mining is determined.In the oblique direction of the working face,the stress concentration area is 6.5~25.3m in the goaf of the goaf and 9.1~46.9m in the goaf,and the working face of the 4# coal seam is the external fault and the internal fault.In the direction of propulsion of the working face,the peak point of stress concentration is located 10 m behind the open cut of the 4# coal seam,and the internal stress ofthe coal seam is lower than the original rock stress within the range of more than6 m in front of the open cut of the 4# coal seam.When the upper group coal working face roadway and open cut eye arrangement,the numerical simulation results can be referred to,avoiding the stress concentration area.(5)The layout plan and supporting scheme of the 4207 working face roadway in the 3# coal seam of the upper coal group were designed.The 4207 working face return airway adopts the external wrong arrangement,the internally staggered distance is 2m;the transportation lane adopts the internal fault arrangement.In the mode,the internal error distance is 3m,and the opening surface of the 4207 working surface is arranged at the position 6m ahead of the opening of the lower coal working face.The roadway adopts the anchor rod + anchor cable + metal mesh joint support method.(6)After the scheme is determined,the deformation of surrounding rock in tunneling to 150 m is monitored.The influence of tunneling is about 30 m.The deformation of surrounding rock is small and the surrounding rock control is better.As of December 2018,the coal seams of the 3# coal seam of the Yongning Coal Mine have successfully recovered 4 working faces,and there is no obvious occurrence of mine pressure during the mining process,and the economic benefits have improved significantly,indicating that the research results are better.Application effect.