Study On Optimization Of Bolt Support Parameters For Large Section Coal Roadway In Shallow Coal Seam

The deformation and failure of large-section coal roadway in shallow coal seam of South Shenmu mining area in Nourth Shaanxi is serious,which will affect the safe and efficient production of mining area.It is of great significance to carry out research on large section coal roadway support countermeasures.This paper takes the 25206 working face of 5-2 coal seam in Hongliulin Coal Mine as the background.Through the combination of field measurement,numerical calculation and theoretical analysis,the physico-mechanical properties of the surrounding rock and the deformation characteristics and laws of the roadway are mastered.The parameters of the coal roadway bolt support in the 5-2 coal seam are optimized,which provides reference for large-section coal roadway support with similar mining conditions.Through the on-site observation of the surrounding rock deformation of the 25206 auxiliary transport roadway,concluded the loose zone of the roadway gang is 0.95m and the loose zone of the roof is lm,during the excavation.The loose zone of the roadway is 1.05m,and the roof loose zone is 1.35m,during the mining.When the working face is advanced 30m ahead of the coal wall,the settlement value and convergence value of the roof are increasing continuously;the force of the anchor increases with the advancing distance,and the force curve shows a steady,increasing and stable trend.Using the ANSYS software,a square and arched pallet model was established,and the size and shape of the pallet were analyzed.The influence of the stress distribution on the up per and lower surfaces of the pallet were obtained,during the pre-tightening stage and the working stage.Obtained the suitable size was arched plate 15o×150×8mm.The simulation of different anchor lengths by FLAC3D numerical simulation,concluded that with the increase of anchor length,the maximum force of anchor is reduced,and the maximum vertical displacement is 25.8mm.The effect of anchor length on vertical displacement is smaller.The numerical simulation analysis of bolted joint support shows that the compressive stress value and the shape and range of the spherical high-pressure stress zone are almost the same near the anchor pallet,and the compressive stress value and range formed near the anchor anchor anchoring end are larger,difference.Theoretical calculations show the supporting parameters of the top and bottom bolts of the 25206 rubber tank in Hongliulin Coal Mine.The top bolt parameters are ?18×2.2m,and the spacing between left-handed steel bolts is 1.25m×1.2m.The side/coal side lane bolting parameters are ?16× 1.6m,and the distance between the FRP anchor/twisted resin anchors is 1.3 m×1.2 m.Combined with numerical analysis,before optimization of support parameters,concluded that the deformation and stress of the surrounding rock change little,during the excavation process.However,after optimization of support parameters,the deformation and stress change of the surrounding rock are optimized,also the stability of the surrounding rock of the roadway can still be ensured,and the field practice is good.At the same time,based on the optimization results of support parameters,each 1m extension of 5-2 coal roadway can save 187 yuan,and the total footage of mine 5-2 coal roadway in 2018 is 21237 meters,saving a total cost of 3.97 million yuan.The mining area has achieved significant economic benefits,and the excavation efficiency increased by 7%.