基于整环足尺试验的盾构隧道破坏机制及纵缝外弧面变形分析

Failure Mechanism of Shield Tunnel Based on Full-Scale Experiment and Analysis of Longitudinal Joint′s Outboard Deformation

为探明隧道的结构破坏机制及外弧面纵缝变形规律,以某病害多、受力工况复杂的区间地铁盾构隧道为对象,开展2组错缝拼装盾构隧道整环足尺试验,挖掘盾构隧道全过程结构破坏特征点,归纳收敛变形-外弧面纵缝变形关联关系,并获得收敛变形-外弧面纵缝变形关键指标。研究结果表明:1)盾构隧道收敛变形达到20~30 mm时开始出现沿隧道纵向的管片裂缝;2)盾构隧道结构破坏可分为弹性、弹塑性和极限状态3个阶段,极限状态时可观察到管片本体受压破坏及多处纵缝破损;3)盾构隧道腰部纵缝外弧面张开量与收敛变形、拼装角度高度关联。

To investigate the structural failure mechanism and longitudinal joint′s outboard deformation of shield tunnel,two groups of full-scale experiments on staggered joint assembled shield tunnel are conducted based on a shield tunnel with many defects and complex load conditions.The key points of structural failure in the whole process of shield tunneling are excavated,the correlation between convergence deformation and longitudinal joint deformation is summarized,and the key indexes are obtained.The results show the following:(1)When the convergence deformation of shield tunnel reaches 20~30 mm,segment cracks along the longitudinal direction of the tunnel occur.(2)The structural failure of shield tunnel can be divided into three stages,i.e.,elastic,elastoplastic,and ultimate stages,and when it reaches the ultimate state,some segments and longitudinal joints are damaged by compression.(3)The outboard deformation of waist longitudinal joint is highly correlated with the convergence deformation and assembly angle.