Mechanism of Load-Transfer Between Coal Pillars with Different Widths in Mining the Short-Range Seams

Aiming at the situation of mining short-range coal seams in Fenxi mining area,we analyze the factors affecting the re-distribution of stress of coal-rock mass near the coal pillar and its adjacent area.In addition,we study the mechanism of load-transfer between coal pillars and in coal-rock mass using the finite difference program FLAC3D.The result indicates that the effect of stress concentration in coal pillars on the re-distribution of floor stress is greater than that on the roof stress;the stress concentration factors of coal and rock within the coal pillars with different widths is different from those in the roof and floor,and as the increase of width of the coal seam,the maximum principal stress in the coal seam increases first and then decreases;as the width of the coal seam increases,the stress influence diffusion angle of the coal and rock under the coal pillar decreases and gradually reaches a constant.The stress re-distribution in the 10#~11# coal seams at the Shuiyu coal mine is obviously affected by the 9# coal seam mining.Based on the calculation of the stress influence diffusion angle of the coal pillars in the 9# coal seam,the layout of the roadways in the 10#~11# coal seams is designed following the main principle that the layout of the roadways should be in the area with a relatively low stress.And the in-situ monitoring results show that the deformation is not severe and the supporting effect is good.