Study on the mining roadway layout in lower coal seam of shallow-buried coal seam group under the comprehensive influence of overburden stress and air leakage
In view of the determining problem of reasonable roadway layout position in the lower working face under the influence of the upper remained coal pillar in shallow-buried close coal seam group,taking Huojitu Coal Mine as an example,the discrete element method(DEM)was used to study the floor stress distribution of the remained coal pillar and the fracture development characteristics of the upper and lower coal seam goafs.The results showed that after the mining of No.12 coal seam,the difference of vertical stress and principal stress increased within 20 m of the horizontal distance of No.22 coal seam from the upper coal pillar,and the horizontal stress of No.22 coal seam was lower inside the section coal pillar.The principal stress difference of surrounding rock on both sides of the roadway was large when the layout of the roadway in the lower coal seam was external-misaligned type or overlapped type,and the secondary migration of the interlayer and the overlying strata of upper old goaf was severe when the No.22 coal seam working face was mined under the staggered and overlapping layout modes,and the oblique fracture zones on both sides of the goaf were well developed and penetrated.With the internal-staggered layout type,the principal stress difference of the surrounding rock on both sides of the roadway decreased firstly and then increased with the increase of the distance from the coal pillar,and the principal stress difference reached the lowest at 25-35 m from the coal pillar,when the subsidence of the overlying strata in the upper goaf was balanced,and the closure of the fracture zone was good,which greatly prevented the development of the air leakage channel between the surface and the interlayer.
closed distance coal seam groupshallow-buried coal seamdiscrete element methodroadway layoutair leakage channelfracture development
NETL
NSTL
万方数据
