Study On The Relationship Between Rib Rpacing And Anchorage Effect Of Bolt

Bolt support is an important way to support underground mine roadway.The shape of bolt has an important effect on its anchoring effect.In order to determine reasonable rib spacing of bolt and to improve anchoring effect of bolt,this paper discusses the relationship between bolt rib spacing and anchoring effect of bolt.Based on the theoretical analysis,a new analytical method of anchoring effect under thick wall theory is established,and three indexes of circumference strain,shear expansion displacement and energy dissipation are proposed.Right-hand twist threded bolt and left-hand twist threded bolt which were anchored in the wall thickness of 5.5 mm and 7.0 mm were performed an anchoring mechanics test by means of laboratory tests and numerical simulations,determination of drawing force,shear expansion displacement,energy dissipation,sleeve circumference strain and other parameters.The results show that with increase of spacing anchoring in 5.5 mm and 7.0 mm sleeves.For right-hand twist threded bolt,shear expansion displacement and energy dissipation are approximately linearly increasing,and circumference strain increases first and then decreases and then increases,and both have a maximum for 60 mm spacing bolt,pull force increased first and then decreased,the maximum fore value appears at spacing of 48 mm.For left-hand twist threded bolt,shear expansion displacement tends to be gentle after approximately linear growth,energy dissipation increased first and then flattened,and both maximum value appears at pitch of 48 mm,and pull-out force increased first and then decreased and then increased,the maximum value appeared at spaceing of 24 mm,circumference strain show a linear trend of growth(5.5 mm)and increase first then decrease and then increase(7 mm),the maximum values appear in the rib spacing of 48 mm and 24 mm,respectively.The numerical simulation shows that stress concentration area is easy to be formed at bolt-resin interface and stress distribution of anchoring section shows an exponential distribution trend,the distribution of transverse ribs have a significant effect on stress distribution of the sleeve surface.Through research of this paper,it is concluded that increase of rib spacing has a great influence on optimization of anchorage performance.Experimental results will provide necessary reference for field application and related experimental research in the future.