Research On The Deformation And Damage Law Of The Surrounding Rock And Support Technology Of The Gob-side Entry Retained In Xiaohezui Coal Mine’s Extremely Short-distance Thin Coal Seam

As the shallow coal seams with good conditions are exhausted,the mining of thin coal seams in very close proximity is getting more and more attention from mining workers.In order to improve the coal output and alleviate the problems such as the actual mining succession tension,large amount of roadway excavation and low coal resource extraction rate,the use of along-air stay roadway is undoubtedly an effective technical means.Therefore,this paper researches the key technology of 1216(21)gob-side entry retained in Xiaohezui coal mine.Using theoretical analysis,indoor experiments,numerical simulation and field monitoring,the deformation and damage law of the overburden rock of the very close thin coal seam mining site is studied and the corresponding support technology is proposed.The main work and research results are as follows.Firstly,the law of deformation and damage of the surrounding rocks along the thin coal seam with large mining height in very close proximity to the gob-side entry retained was studied,and the mechanical model of any point at the bottom plate of the upper mining area was established,and the maximum damage depth of the bottom plate of the upper mining area was derived from this model,and the fragmentation state of the surrounding rocks of the lower roof plate was determined.Designed the "coal-rock-coal" combination with the on-site rock structure.The uniaxial compression test results show that the height of the rock body determines the overall damage of the specimen,and the higher the height of the rock body,the more complete the specimen is.The force situation of the top plate of the lower lane was analyzed,and the required support resistance of the lane side support body was solved accordingly,and the "soft-hard" lane side support body structure was designed accordingly.Secondly,according to the control points of the surrounding rock along the empty stay lane,it is determined that the support of the surrounding rock of the lane should control the sinking and rotation of the lane roof to ensure the integrity of the surrounding rock of the lane;strengthen the lateral support of the solid coal gang to limit the displacement of the solid coal gang to the maximum;adopt the basic principle of coordinating and cosupporting the basic support in the lane,strengthening the support in the lane and masonry of the support body beside the lane,and put forward the basic support scheme in the lane,and analyze the stress distribution and displacement law of the surrounding rock of the lane under different support schemes by numerical simulation.Finally,the means of field monitoring was used to conclude that the deformation damage of the surrounding rock along the gob-side entry retained of the thin coal seam in very close distance has obvious stages.When the working face is retrieved,there is a certain lag in the delamination of the top plate of the roadway,and within 40 m behind the working face is the key area where the delamination of the top plate occurs,and the retrieval of the working face does not cause serious impact on the solid coal gang and the surrounding rocks above it.According to the law of surrounding rock stress distribution,the law of deformation and damage of the top plate and two helpers,and the optimized design scheme of the support body parameters beside the lane,the support scheme of "anchor rod(cable)+ metal mesh + slurry spray + wall" is formed for the very close thin coal seam gob-side entry retained.