软土地铁隧道纵向不均匀沉降导致的管片接头环缝开裂研究

STUDY ON LONGITUDINAL CRACK OF SHIELD TUNNEL SEGMENT JOINT DUE TO ASYMMETRIC SETTLEMENT IN SOFT SOIL

地铁通车运行后,会因多种原因产生盾构隧道纵向不均匀沉降,诸如列车振动、渗漏、土体不均匀性等。隧道纵向过大,不均匀沉降会严重影响地铁的运行安全。基于某地铁隧道的纵向沉降实测数据,分析了纵向沉降对隧道结构安全性的影响。首先用抛物线分段模拟了隧道的纵向变形,得出了隧道纵向变形曲率;然后以等效轴向刚度模型为基础,建立了隧道纵向变形曲率与隧道管片接头环缝张开量之间的关系。通过对计算结果的分析,可较全面地了解整个隧道的纵向沉降以及隧道管片环缝张开量的现状,从而为软土隧道的运营阶段维护、改善结构和防水设计、施工方法等提供依据。

After the metro was put into operation, there has been increasing longitudinal nonuniform settlements of shield tunnel due to various causes including the vibration load of train, leakage of tunnel, different soil properties, etc.. This kind of nonuniform settlement will greatly endanger the safety of the train. Based on the measured data for longitudinal settlements of a tunnel in soft soil, the security of the tunnel caused by settlements is studied. Firstly, the longitudinal settlement was simulated by polynomial part by part and the relative longitudinal curvature was gained. Secondly, the equivalent axial stiffness model of shield tunnel initiated by a Japanese scholar is introduced. Finally, the relationship between longitudinal curvature and crack of shield tunnel segment joint was found based on the equivalent axial stiffness model of shield tunnel. The results not only can help us to learn the current situation of the longitudinal settlement of shield tunnel and the longitudinal crack of shield tunnel segment joint, but also provide the guidance for tunnel protection, waterproof design and construction technique of shield tunnel.