富水软弱地层盾构区间近距离下穿既有运营地铁区间设计关键技术研究

Study on Key Techniques about Design of Close Crossing of Shield Tunnel Section beneath Existing Metro Section in Operation in Water-rich Soft Ground

新建地铁区间近距离下穿既有运营线路的情况越来越多,特别在富水软弱地层,地下水位高、土层压缩性高、承载力低,在下穿过程中极易造成既有区间结构较大变形,影响既有运营线路安全。本文以天津地铁4号线盾构区间近距离下穿既有9号线区间为例,通过采用合理的技术措施,保障了工程的顺利实施。此外,通过数值模拟分析了盾构下穿既有线时的变形情况,并与施工实测数据进行对比,变形趋势基本一致,可为后续类似工程提供参考。

In recent years, more and more new metro sections have been constructed to cross beneath existing metro sections in operation. Especially in water-rich soft ground, because there is high water mark, high compressibility of soil layer and poor bearing capacity, the crossing work can easily lead to great structural deformation of existing section, which will affect the safe running of the existing metro lines. This paper takes Tianjin Metro Line 4 as example. The shield tunnel section of Tianjin Metro Line 4 crossed beneath existing section of Tianjin Metro Line 9 within short distance. Through the adoption of reasonable technical measures to ensure the smooth implementation of the project. Besides, finite element numerical simulation was used to further analyze the deformation situation where shield tunnel section crossed beneath the existing metro section. Compared to the measured data during construction, the deformation trend is basically the same. It provides a source of reference for similar future projects.