Analogy simulation test on strengthening effect for pretention of bolts on anchorage body

Abstract：Bolt pretension has an important part in roadway support,but the study on strengthening characteristics of anchorage body with pre-stressed bolts still has many problems.Mechanics characteristics of detached anchorage body was researched by using RMT-150C testing machine,which was fabricated by wax-sand,pretension bolts and plainstrain restrain device.The results indicate that strength enhancement factor of peak strength,residual strength are positive correlation with rock strength and pretension of bolts.Strength enhancement factor is gradually increasing with pretension when rock strength is constant,and the residual strength enhancement factor of pretention of is greater than that of peak.There are corresponding relationship with stress-strain curve and bolts loads.Congruent relationship exists between stress-strain curve and bolt load.Before surrender point,bolt load increases slowly;however which increases rapidly after surrender point.Bolt load increases gradually on post-peak points,and constantly descends on flow phase.The higher strength of rock is,the lower increase rate of bolts loads are with the same pretension.The increase rate smaller is,the higher pretension is with the same rock.The loss of pretension in failure stage is much more of soft rock than that of hard rock.The strengthening effect in soft rock is obvious than that of in hard rock.Site practice shows that surrounding rock deformation can be decreased effectively with high bolt pretension.