考虑灌浆料龄期的钢筋-金属波纹管浆锚连接锚固性能试验研究

Experimental study on anchorage property of rebar-metallic bellows slurry anchor connection considering grout age

为研究钢筋-金属波纹管浆锚连接的锚固性能,设计制作18组连接件,并完成拉拔试验。基于试验结果研究钢筋锚固长度la、灌浆料龄期T与螺旋箍筋约束对浆锚连接锚固性能的影响。试验结果表明,所有锚固钢筋均经历完整的弹性阶段与屈服阶段,最终试件表现为钢筋粘结-滑移破坏、钢筋拉断两种破坏形式。当灌浆料龄期T=3 d时,试件均发生粘结-滑移破坏;当灌浆料龄期T=7 d且锚固长度la≥13d时,试件均出现钢筋断裂破坏;当灌浆料龄期T=28 d时,无配箍试件锚固长度l_(a)=7d时、配箍试件l_(a)=5d时出现钢筋断裂破坏。提高钢筋锚固长度、灌浆料龄期与配置螺旋箍筋约束有利于试件的极限强度提高,并趋近钢筋实验抗拉强度,显著降低钢筋的弹性阶段滑移量,提高初始刚度,提升试件的锚固性能。实际工程中,当孔径比不小于2.6时,为确保3 d与7 d锚固性能,锚固长度应大于13d;为确保正常工作中钢筋充分发挥其力学性能,锚固长度应不小于10d。

In order to study the anchorage property of rebar-metallic bellows slurry anchor connection,18 groups of connection specimens were designed and fabricated in this study,and the pull-out tests were completed.The influences of anchorage length la,grouting material curing age T and spiral confinement on the anchorage property of the connection were analyzed based on the test results.The experimental results show that all the anchored rebars had undergone integral elastic stage and yielding stage,and the ultimate performance of specimens were bond slip failure and rebar fracture.When T=3 d,bond-slip failure occurred in all specimens.When T=7 d and la≥13d,rebars fractured.When T=28 d,specimens whose l_(a)=7d without stirrup and l_(a)=5d with stirrup began to failure of rebar fracture.With application of spiral confinement and the increase of anchorage length and grout age,the ultimate strength of specimens increased first and then approached to the tensile strength of rebar,the maximum sliding displacement of rebars in the elastic stage decreased significantly,the initial stiffness of specimens increased,and anchorage property improved significantly.In engineering practice,when D/d≥2.6,the anchorage length should be greater than 13d to ensure the anchorage performance of 3 d and 7 d.In order to fully exert its mechanical properties in normal work stage,anchorage length is prohibited to be less than 10d.