Study On Safety Error Distance Of Coal Seam Mining In Shallow Buried Near Coal Seam

Due to the small spacing of coal seams in the close coal seams,the mining of upper coal seams will have an impact on the mining of lower coal seam.After the upper coal seam mining,the original rock stress balance is destroyed,such that the movement of the stope wall rock and surrounding rock stress of the internal distribution,the result will cause the roof and floor rock mass displacement and deformation,even failure.Affected by coal mining on the working face,this coal pillar abutment pressure load and gob caving coal gangue work together under the close above the coal seam,the upper coal seam mining,the distribution rules of surrounding rock stress of the upper coal mining goaf floor after floor deformation and failure characteristics,scope of deformation damage size and below the stress distribution of coal pillar to determine the position of the lower coal seam section coal pillar and the reasonable size of coal pillar and effective supporting method has important guiding significance.Based on the shallow buried close distance coal seam group feng tower after the 2#coal seam mining in coal mine,4#coal seam working face as an example,the upper left coal mining of lower coal coal pillar,the influence of the similar material simulation experiment and numerical calculation to study the structure characteristics,the stress evolution rule of working surface rock and support load.According to the theoretical calculation,the maximum damage depth of Dmax is 11.97m(the interval between two layers is 14.55m),and the influence range of 2#coal pillar is 10.42m.Fluctuation of coal seam is not in the same vertical position,mining in 4#coal mining basic is not affected by the 2#coal,but at the same vertical position of coal drift up and down or up and down coal mining,roadway is due to the stress superposition area in a certain degree of damage.Through similar material simulation experiment,mainly concentrated in the working face in front of the working face advancing stress peak around 10 m(expected within 8～12 m strong),the stress reducing area within the scope of the 35～80 m,abutment pressure significantly affect the distance of 35 m.In this paper,the stress distribution characteristics of the lower seam mining field under different fault distance are simulated by UDEC,and the reasonable error distance scheme is determined.The open-cut eye is arranged in the middle area of the peak area and the working face of the mining area to avoid the stress peak area,and the opening and cutting eyes are arranged at 8m from the coal opening.In view of the roadway,a longer service life,therefore the fluctuation extent of coal seam coal pillar stagger 36 m,based on the optimization of coal pillar dimension of coal pillar in staggered section,ensure safety in production at the same time improve the coal recovery rate.Finally,the feasibility of the design scheme is analyzed by field monitoring.