高轴压作用下盾构隧道复杂接缝面管片接头抗弯试验

在采用盾构法应对大埋深、高水压等特殊环境时，具有凹凸榫、双侧止水构造的复杂接缝面接头大量运用，在该情况下其抗弯性能较为复杂。文章结合广深港高速铁路狮子洋隧道工程，针对高轴压作用下复杂接缝面管片接头的抗弯性能、破坏特征开展了足尺试验研究，试验结果表明，高压作用下管片接头抗弯刚度在初始段小弯矩作用下增长近似线性，后段呈明显非线性，而且轴力水平越大线性段保持越长；由于负弯曲时管片内侧接触传力区混凝土参与受压，增加了接缝面的抗弯能力，使负弯荷载下抗弯刚度比正弯荷载下抗弯刚度略大。接缝面张开情况随弯矩呈“台阶状”变化，在接缝面线性张开时轴力的增长对于接缝面张开的约束作用不明显，而非线性增长阶段轴力对与张开量的约束明显；止水材料对于接头抗弯刚度的影响很小，在进行管片接头抗弯刚度的设计与计算分析时可忽略不计；正弯荷载与负弯荷载作用时管片接头的破坏过程不同，正弯荷载作用下接头螺栓先于接头破坏，负弯荷载作用下接头破坏时螺栓未破坏。研究结果可为盾构法隧道的设计、施工和相关研究提供重要参考。

Bending tests of segment joint with complex interface for shield tunnel under high axial pressure

When using shield tunneling method facing the special circumstances such as large depth, high water pressure, the complex interface joints with tenon or mortise, and bilateral sealing were widely used. And in which case the bending performance of segmental joint is more complex. With the Shiziyang tunnel project of Guangzhou-Shenzhen-Hong Kong high-speed railway taken as an example, the full-scale tests were carried out to study the bending behavior and failure characteristics of segment joint with complex interface under high axial pressure. The results show that the bending stiffness of the segment joint with complex interface under high pressure linearly increases under small bending moment in the initial stage, but the behavior appears to be obviously nonlinear in the later stage. Moreover, the higher the axial force level is, the longer the linear stage shall be. Due to the participation of concrete in the inner-side contact force-transferring region at hogging bending into compression, the bending resistance of the interface can be increased, leading to a slightly larger bending stiffness at hogging bending compared to that at positive bending. The joint opening condition may change with bending moment in the step-like style. When the interface linearly opens, the increase of axial force appears to have an unobvious restraint on the opening of interface, but in the nonlinear stage, an obvious restraint from the axial force on the magnitude of interface opening can be observed. Influence of sealing material on bending stiffness of joint is small, so that it can be ignored in the design and analysis of bending stiffness of segment joint. The failure processes of segment joint under the positive bending load and negative bending load are different. Under the positive bending load the joint bolt may fail before the damage of joint, while under the negative bending load the joint bolt may not fail although the joint already fail. The research can provide an important reference for shield tunnel design, construction and related research.