Study On Gob-side Entry Retaining Of Ascending Ming In Gently Inclined And(extremely) Close Thin Coal Group

Coal is an essential resource for social development,but there are contradictions between its discovery and safety,environmental protection,energy regeneration,etc.With the increase of mining depth,the occurrence condition of coal seam is complex and must be selected as the protective layer,the close thin coal seam group is more concerned,how to realize its safe and efficient production has become a problem that can not be ignored.The long-term practical experience shows that the gob side entry retaining has obvious advantages in the mine production,but the occurrence conditions of the short-distance thin coal seam group are complex.When the gob side entry retaining is carried out under the influence of the superposition mining conditions of different coal seam working faces,the mine pressure is obvious,and the roadway maintenance is difficult,which seriously affects the safety and efficient production of the mine.In order to solve the problem of stability of gob side entry in the mining process of short-distance thin coal seam group,this paper takes Xuyong coal mine in Sichuan Province as the engineering background,adopts the method of theoretical analysis,numerical simulation and field test,and studies the upward mining gob side entry in the section of gently inclined(extremely)short-distance thin coal seam group.The main results are as follows:(1)Under the mining procedure of " Different Coal Seam Downward mining,the same coal seam section upward mining ",the movement rule of the strata under the influence of repeated mining is studied.Under the three conditions of the first coal seam(C19 coal seam),the very close coal seam(C20 coal seam,with the spacing of 3M between C19 coal seam)and the very close coal seam(C24 coal seam,with the spacing of 10 m between C20 coal seam),the support of the air lane along the goaf is obtained Relationship with surrounding rock.(2)According to the relationship between the support and the surrounding rock,a variety of retaining schemes are proposed for the above three cases.Through the numerical simulation and analysis of UDEC,the optimal supporting schemes are obtained under various conditions.(3)The accuracy of theoretical analysis and numerical simulation results is verified by field test and observation of mine pressure at the same time,and satisfactory technical and economic benefits are obtained.