上海软土地铁隧道沉降及横向收敛变形的原因分析及典型特征

Cause analysis and typical characteristics of settlement and transverse convergence deformation of metro tunnel in soft ground in Shanghai

软土地区盾构法隧道变形主要包括纵向不均匀沉降和横向收敛变形。当纵向沉降累计变形、不均匀变形坡度以及变形速率等达到一定程度,横向水平直径相对标准圆变化量超过一定数值,就会引起隧道结构受力的安全问题。上海地铁自1995年1号线开通后,针对地下线路每年2次沉降监测,高架区间每年1次沉降监测,自2011年全路网地下隧道每年1次横向收敛监测,积累了大量宝贵的实测数据。对上海地铁隧道近25年的变形数据进行分析,总结了隧道纵向不均匀沉降原因及典型特征。对四种隧道横向收敛变形的分析方法和结论进行对比,总结横向收敛变形的特征。可为类似软土地质条件的城市地铁隧道结构设计、施工及运营期维护保障提供参考,减小结构破坏风险,保障城市地铁运营安全。

The deformation of shield tunnel in soft soil area generally includes longitudinal uneven settlement deformation and transverse convergence deformation. When the cumulative deformation of longitudinal settlement,uneven deformation gradient and deformation rate reach a certain degree,the variation of horizontal diameter compared to the standard circle exceeds a certain value,it will cause safety problems in the tunnel structure. Since the Shanghai Metro Line 1 was put into operation in 1995,we have made the settlement monitoring two times per year for underground lines,a settlement monitoring per year in the elevated section,and a transverse convergence monitoring per year for the underground tunnels since 2011,accumulating a large amount of valuable measured data.This paper analyzes the deformation data of the Shanghai metro tunnel in the past 25 years,and summarizes the causes and typical characteristics of the longitudinal uneven settlement of the tunnel. Compared four analysis methods and its conclusions of the transverse convergence deformation of tunnels,summarize the characteristics of transverse convergence deformation. It can provide reference for structure design,engineering construction and maintenance of operation period of urban metro tunnels with similar soft ground conditions,reducing the risk of structure damage and ensuring the safety of urban metro operations.