Study on position of open-off cut of upper coal seam working face in close range coal seams

Guo Yaosheng; Su Lei; Ma Yunfeng

doi:10.19896/j.cnki.mtkj.2025.05.003

Abstract：To study the influence of the position of the open-off cut and the spacing between the lower coal seams on the roadway under close range coal seam conditions,taking the No.105 working face of Liuta Coal Mine 1-2 upper coal seam as the engineering background,by combining theoretical analysis,numerical simulation,and on-site application,the failure characteristics of the plastic zone of the sur-rounding rock in the goaf floor of the upper coal seam working face and the lower coal seam roadway were analyzed at different open-off cut positions.The results show that with the increase of the distance between the open-off cut position and the lower coal seam,the plas-tic zone of the roadway and the plastic zone of the working face floor change from the through state to the separate state,and the deform-ation of the surrounding rock of the roadway group rapidly decreases;when the position of the open-off cut is selected at the layer spac-ing of 8 m,the plastic zone around the roadway does not go through to the working face floor,the height of the elastic zone is greater than 2 m,and the maximum deformation is 13.8 mm,at this time,the mining of the upper coal seam working face has the least influence on the lower roadway.The field measurement shows that when the open-off cut is selected at the layer spacing of 8 m,with a displacement of 10-16 mm between the two sides of the roadway and 8-15 mm between the roof and floor,the surrounding rock control effect meets the production requirements.