注浆纠偏隧道水平位移的数值模拟

Numerical Simulation on Horizontal Deformation Control of Tunnel by Grouting

为研究影响注浆效果的影响因素,以天津市某基坑工程为背景,在既有隧道与基坑之间的场地开展原位注浆试验,同时利用大型有限元模拟软件PLAXIS模拟注浆过程,研究了注浆距离、注浆量、注浆深度、基坑开挖以及多孔同时注浆对注浆效果的影响。另外,对比分析了基坑周边有隧道和基坑周边无隧道2种情况下隧道与土体的变形规律。结果表明:采用注浆法控制隧道变形时,协调选择注浆量与注浆距离才能达到较高的注浆效率,注浆量应根据基坑开挖情况及隧道位移情况及时调整,同时后续需要在相同或相近位置进行重复注浆补偿隧道位移恢复值,才能使隧道变形得到整体控制;当注浆范围顶部埋深与隧道轴线埋深相同时,隧道的水平位移恢复值最大,为注浆深度的确定提供了参考;基坑开挖后注浆纠偏隧道位移的效果相较于无基坑情况时出现一定程度的削弱,并且注浆量越大,注浆效果削弱越明显;根据注浆影响范围布置注浆孔,充分利用多孔注浆的叠加效应能够使隧道变形得到均匀控制。

In order to study the influencing factors affecting the grouting effect,based on a foundation pit project in Tianjin,an in-situ grouting test was carried out in the site between the existing tunnel and the foundation pit.At the same time,the large-scale finite element simulation software PLAXIS was used to simulate the grouting process,and the effects of grouting distance,grouting amount,grouting depth,foundation pit excavation and porous grouting on the grouting effect were studied.In addition,the deformation laws of tunnel and soil were compared and analyzed when there was a tunnel around the foundation pit and no tunnel around the foundation pit.The results show that when grouting method is used to control tunnel deformation,high grouting efficiency can be achieved by coordinating the selection of grouting amount and grouting distance.The grouting amount shall be adjusted in time according to the foundation pit excavation and tunnel displacement.At the same time,repeated grouting shall be carried out at the same or similar positions to compensate the tunnel displacement recovery value,so as to control the overall tunnel deformation.When the top buried depth of the grouting range is the same as that of the tunnel axis,the horizontal displacement recovery value of the tunnel is the largest,which provides a reference for the determination of the grouting depth.The effect of grouting correction of tunnel displacement after foundation pit excavation is weakened to a certain extent compared with that without foundation pit,and the greater the amount of grouting,the more obvious the weakening of grouting effect is.The tunnel deformation can be controlled uniformly by arranging grouting holes according to the influence range of grouting and making full use of the superposition effect of porous grouting.