拼装式矩形隧道环向接头抗弯性能试验

矩形隧道因空间利用率高、覆土浅和施工成本相对低廉等特点，成为最为较合适的断面形式，而环向接头性能对矩形隧道的抗弯承载力有重要影响。本文对一种矩形隧道的环向卯榫接头开展了大尺寸模型抗弯试验，探讨了拼装式隧道环向接头的结构变形和损伤模式。研究结果表明，卯榫接头在承受极限破坏前，接头的混凝土和钢筋应变均低于极限应变；螺杆接头的变形量比较小，主要原因是螺杆的锚固和止裂机制，使接头闭合和开裂阶段的最大张开宽度和压缩量都处于规范范围内；螺杆接头受力后表现出压缩弯曲破坏模式，其主要特征是前期承压，中期塑性变形与小扩张，后期压缩扩张，并导致接头破坏；卯榫接头受力变形稳定、承载能力高、控制裂隙能力强、塑性好而不发生脆性破坏，所以螺杆接头适合作为装配式框架隧道的接头方案。

Experimental study on bending behavior of circumferential joint of assembled rectangular tunnel

due to the characteristics of high space utilization, shallow soil cover and relatively low construction cost, rectangular tunnel has become the most suitable section form, and the performance of circumferential joint has an important impact on the flexural capacity of rectangular tunnel. In this paper, a large-scale model bending test of a circular tenon joint of rectangular tunnel is carried out, and the structural deformation and damage mode of assembled tunnel circular joint are discussed. The results show that before the mortise and tenon joint bears the ultimate failure, the strains of concrete and reinforcement are lower than the ultimate strain. The deformation of screw joint is relatively small, which is mainly due to the anchoring and crack arrest mechanism of screw, so that the maximum opening width and compression in the closing and cracking stage of joint are within the standard range. The screw joint shows compression bending failure mode after stress, which is mainly characterized by early pressure bearing, medium-term plastic deformation and small expansion, and later compression expansion, which leads to joint failure. The mortise and tenon joint has stable stress and deformation, high bearing capacity, strong crack control ability, good plasticity and no brittle failure, so the screw joint is suitable for the joint scheme of fabricated frame tunnel.