不同变形条件下盾构隧道粘钢加固效果的模型试验研究

Due to the influence of surrounding projects such as earth piling above and excavation of adjacent foundation pits, large deformations of subway tunnel structures have become a common problem. Steel plate bonding reinforcement is a commonly used method for controlling subway deformations. However, the evaluation and analysis of the reinforcement effect of bonded steel plates are currently not clear. Through a 1∶5 indoor model test, the bearing capacity of the structure after steel plate bonding reinforcement under different deformation conditions of the tunnel, the load - displacement relationship and the failure mode of the structure were studied, and the reinforcement effect of steel plate bonding and the reasonable reinforcement timing were analyzed. The test results show that: ① When the tunnel structure deformations are 7.4‰D, 15‰D and 20‰D respectively (D is the outer diameter of the tunnel) and steel plate bonding reinforcement is adopted, the failure loads of the reinforced structure increase by 54.2%, 49.6% and 26.7% respectively compared with the failure load of the original structure. The vertical convergences when the structure is unstable are 60.78, 58.74 and 62.15 mm respectively, and the horizontal expansions are 48.46, 56.28 and 61.68 mm respectively. It indicates that the steel plate bonding can improve the bearing capacity of the structure, but has no great impact on the displacement when the structure is unstable, thus providing a basis for judging the service performance of the structure based on the displacement change; ② A structure deformation of 10‰D to 15‰D is a more reasonable reinforcement timing; ③ The cracking and peeling of the bonding surface between the steel plate and the concrete are the main factors for the failure of the steel plate bonded reinforced structure, and the key part is the joint near the positive bending moment area of the vault. The above research conclusions can provide a theoretical basis for the design and timing selection of steel plate bonding reinforcement for shield tunnels.

由于上方堆土、邻近基坑开挖等周边工程的影响,地铁隧道结构产生较大变形已成为常见问题,粘钢加固作为控制地铁变形的常用手段,然而目前对于粘贴钢板加固效果的评价分析尚不明确。通过1∶5的室内模型试验研究了隧道不同变形条件下粘钢加固后结构的承载性能、荷载位移关系以及结构的破坏模式,分析了粘钢加固效果以及合理的加固时机。试验结果表明:①隧道结构变形分别为7.4‰D,15‰D和20‰D时(D为隧道外径)采取粘钢加固,加固后结构的破坏荷载相对原结构的破坏荷载分别增加了54.2%,49.6%和26.7%,结构失稳时的竖向收敛分别为60.78, 58.74,62.15 mm,水平扩张分别为48.46,56.28,61.68 mm,说明粘钢可以提升结构承载力,但未对结构失稳时的位移量产生较大影响,从而为基于位移变化判断结构服役性能提供了依据;②结构变形10‰D至15‰D作为加固时机较为合理;③钢板与混凝土结合面的开裂与剥离是粘钢加固结构破坏的主要因素,关键部位为拱顶正弯矩区附近接头处。上述研究结论可为盾构隧道粘钢加固设计及时机的选择提供理论基础。