注浆加固对基坑下方既有地铁隧道的变形影响分析

Influence of Grouting Reinforcement on Deformation of Existing Metro Tunnels below Foundation Pits

在既有盾构隧道上方进行基坑开挖,其卸载效应会使得隧道产生一定程度的上浮及变形,进而引发管片开裂、渗漏水等问题,影响其使用性能及耐久性,对地层进行注浆加固是控制隧道上浮及变形的关键手段之一,但目前尚没有统一的加固范围及要求标准。文章在总结国内外现有理论和经验的基础上,以杭州环城北路—天目山路明挖基坑上跨多条既有地铁隧道工程为背景,采用有限元方法分析了基坑注浆加固对下方既有地铁隧道隆起变形及周边环境变形的影响。对比了不同加固区域和加固方式对基坑下方既有隧道隆起变形保护效果的区别,提出了基坑明挖施工时对下方既有地铁隧道及周边环境的保护对策。

The excavation of folundation pits above the existing shield tunnel will cause the tunnel to float and deform to a certain degree,causing problems such as cracking of the segment and leakage of water,affecting its serviceability and durability.Grouting reinforcement is one of the key methods to control the floating and deformation of tunnels,but there is no uniform reinforcement scope and required standards.On the basis of summarizing existing theories and experiences,based on the excavation foundation project of Hangzhou Huancheng North RoadTianmushan Road,and using the finite element method it analyzes the influence of grouting reinforcement of foundation pit on the uplift deformation and surrounding environmental deformation of the underlying existing subway tunnel.The difference between the effect of different reinforcement zones and reinforcement methods on the deformation protection of existing tunnel underneath the pit is compared,and the protection measures for the existing subway tunnel and its surrounding environment during the construction of open pits are proposed.