基于GFRP筋与钢绞线复合式锚杆支护施工的关键技术研究

Research on the Key Technology of Composite Anchor Rod Support Construction Based on GFRP Tendons and Steel Strands

为解决钢绞线锚杆不易切割、不耐腐蚀及大直径GFRP筋锚杆锚固困难的问题,充分结合钢绞线锚杆和GFRP筋锚杆的各项优点,提出了一种新型GFRP筋-钢绞线复合式锚杆支护结构,并对复合式锚杆支护施工的关键技术进行了研究。首先介绍了复合式锚杆的构造,通过GFRP筋-钢绞线双螺母式连接器的静载试验验证了复合式锚杆应用的可行性;其次探讨了其设计与施工的关键技术问题,并对其中的关键技术进行了总结;最后基于北京地铁12号线北岗子站附属结构风道基坑工程,对复合式锚杆进行了现场试验,并将复合式锚杆成功应用于该工程的基坑支护结构中。杆体连接器静载试验结果显示,6个试件均发生理想劈裂破坏且试件锚固效率均满足规范要求,验证了复合式锚杆应用的可行性。对复合式锚杆支护设计与施工关键技术的讨论结果表明,GFRP筋杆体和钢绞线杆体的连接是复合式锚杆承载力稳定发挥的关键;复合式锚杆的张拉应充分考虑GFRP筋的强度和双螺母式连接器的性能;钢绞线的长度应考虑红线位置。复合式锚杆现场试验结果显示,杆体中的GFRP筋在受力过程中仍能保持较好的弹性性质,锚杆在破坏前持荷稳定,3根锚杆承载力均满足设计要求。复合式锚杆的成功应用为基坑工程支护提供了一条新思路,可供类似工程参考。

In order to solve the problems of difficulties in cutting steel strand anchor rods,incorrosive,and challenges in anchoring large diameter GFRP tendon anchor rods,this paper proposes a novel GFRP tendon-steel strand composite anchor rod support structure by combining the advantages of steel strand anchor rods and GFRP tendon anchor rods.The research focuses on the key technologies involved in the construction of composite anchor rod supports.Initially,the structure of the composite anchor rod is introduced and the feasibility of its application is verified by static load tests of GFRP reinforcement-steel strand double-nut connectors;Secondly,the key technical aspects related to the design and construction is discussed in this paper and the essential technologies are summarized;Finally,based on the breezeway pit project of Beigangzi Station of Beijing Metro Line 12,a field test is conducted on the composite anchor rod,successfully applying the composite anchor rod to support structure.The results of the static load tests of rod connector demonstrate that all of the six specimens exhibited optimal splitting damage,and the anchoring efficiency met the specified requirements.The feasibility of composite anchor rods is confirmed.The discussion highlights the crucial role of the connection between GFRP bars and the steel strand body in maintaining stable performance and bearing capacity;Additionally,the tensioning process of the composite anchor rod should carefully consider the strength of GFRP bars and the performance of the double nut connection;The length of the steel strand body should considerate the red line position.The field test results indicate that the GFRP tendons in the rods maintain excellent elasticity during the stressing process.The anchor rods sustain a stable load before damage.The bearing capacity of all three anchor rods meets the design requirements.The successful application of the composite anchor rod provides new idea and reference for the similar foundation pit projects.