综合管廊地基加固与远期盾构隧道修建的相互影响分析

Analysis on Interaction between Foundation Reinforcement of Utility Tunnel and Construction of Long-term Shield Tunnel

随着地铁盾构隧道、城市隧道、城市地下综合管廊等的大量修建,新建隧道下穿/上跨既有隧道及其相互影响已成为隧道工程重点研究的内容之一。对于既有隧道,以往的研究主要集中在城市隧道或盾构隧道。城市地下综合管廊具有埋深浅、宽度小、壁厚薄的特点。因此,当其被双线盾构隧道下穿时,既有隧道结构的内力、地表沉降等也必然不同。基于汾湖站(苏州南站)综合管廊工程,采用MIDAS GTS NX软件建立了三维有限元模型,分析了管廊地基加固对远期地铁盾构隧道修建的影响及其相互作用,以地基加固长度和上下隧道净距作为变量,考虑了盾构机的掘进压、千斤顶推力和管片间的界面。研究结果表明:对于该工程项目,若远期盾构隧道下穿综合管廊,管廊地基加固对管片的内力无明显影响;当双线盾构隧道下穿后,较短长度的地基加固会增大既有管廊的轴力(拉力);对于初始阶段地表沉降,地基加固均增大了X向(垂直管廊方向)、Y向(平行管廊方向)的沉降值,但显著减小了盾构隧道下穿后地表的隆起值。

With the construction of a large number of subway shield tunnels,urban tunnels and urban underground utility tunnels,the new tunnels crossing over or below the existing tunnels and the interaction have become one of the key research contents of tunnel engineering.For the existing tunnels,the previous studies have mainly focused on the urban tunnels or shield tunnels.The urban underground utility tunnels have the characteristics of shallow burial depth,small width and thin wall thickness.Therefore,when it is under-passed by a double-line shield tunnel,the internal force and surface settlement of the existing tunnel structure will inevitably be different.Based on the utility tunnel project of Fenhu Station(South Suzhou Railway Station),a three-dimensional finite element model is established by using Midas GTS NX software to analyze the influence of utility tunnel foundation reinforcement on the construction of long-term subway shield tunnel and its interaction.Taking the length of foundation reinforcement and the clear distance between the upper and lower tunnels as the variables,the tunneling pressure of shield machine,the jack thrust and the interface between segments are considered.The study results show that for the project,if the long-term shield tunnel passes through the utility tunnel,the foundation reinforcement of the utility tunnel has no obvious effect on the internal force of the segments.When the double-line shield tunnel passes underneath,the shorter length of foundation reinforcement will increase the axial force(tension)of the existing utility tunnel.For the initial stage of surface settlement,the foundation reinforcement will increase the settlement values of X direction(vertical utility tunnel direction)and Y direction(parallel utility tunnel direction),but significantly reduces the uplift value of the surface after the shield tunnel passes underneath.