Load Distribution And Failure Evolution Of Left-hand Twist Thread Steel Prestressed Bolt Without Longitudal Bar Influenced By Rib

Nowadays bolt with thread steel rib is the main bolt type in coal mine,however,the bolt types usually were simplied to rod bolt when researching on thread steel bolt load distribution and failure,so it is difficult to analysis rib mechanical behavior in bolt load distribution and failure.The load distribution and failure of fully grouted bolt under thread steel rib have been analyzed by shear displacement theory and ABAQUS simulation.Results show that:(1)The shear stress distribution of the resin and bolt interface along axis is zigzag,and interface shear stress near rib is maximum.stress concentration factor at the drawing terminal rib is more than 2,foreshowing that interface is easily to failure.The shear stress distribution of the resin and bolt interface along axis on thread steel bolt and rob bolt is similar,foreshowing that rib has little mechanical effect on rock.(2)The resin and bolt interface near drawing terminal rib is failure firstly under drawing,but the shear stress in the broken interface can keep large value.The pull-off strength of thread steel bolt is more than the rob's,because the rib still have mechanical effect on rock when the local interface is failure,so the advantage of rib mechanical behavior is reflected when the bolt and rock system began to damage.Reasonably improving rib profile parameters can enhance pull-off strength and residual strength.Terminal retarding fully grouted pre-stress bolt construction scheme have been analyzed.The simulation methods of prestress and anchoring force which can be used for roadway supporting engineering scale simulation.Results show that terminal retarding method is more sensitive and effective to rock swelling deformation than whole retarding at the same time.