软土地区深基坑临近地铁隧道群施工影响实测分析

Analysis of Measured Data of Construction Influence of Deep Excavation Adjacent to Metro Tunnel Groups in Soft Soil Area

为研究杭州软黏土地区不规则深基坑开挖过程中围护结构受力、变形规律及其对周围环境的影响,并论述隧道注浆纠偏技术的变形控制效果,本文采用施工全过程系统监测方法,以杭州某临近隧道群的基坑B3-1-2分坑施工为例开展系列分析。结果表明:由于受力状态不同,各挡墙墙身位移随深度呈现不同的变化趋势,最大位移受注浆纠偏施工影响且大多向坑外发展;北侧挡墙墙顶位移变化均较小,其余挡墙墙顶水平位移向坑内发展而竖向位移先发生隆起再下沉的变形;支撑轴力与墙顶水平位移呈正相关变化关系;受场地空间制约,地表监测沉降值随基坑边距离增大而逐渐增大;得益于分坑开挖施工策略和MJS(metro jet system)桩隔离作用,分坑B3-1-2开挖对1号线影响较小;隧道注浆纠偏技术能有效控制隧道沉降和侧移发展。研究成果可为相关深基坑工程的设计、施工、监测提供工程借鉴。

In order to study the stress and deformation law of the retaining structure and its impact on the surrounding environment during the excavation of irregular deep foundation pit in the soft clay area of Hangzhou,and to discuss the deformation control effect of the tunnel grouting correction technology,a series of analysis was carried out by using the system monitoring method in the whole construction process,taking the B3-1-2 sub-pit construction of a nearby tunnel group in Hangzhou as an example.The results show that due to different stress states,the displacement of each retaining wall body varies with the depth,and the maximum displacement is affected by the grouting construction and mostly develops outside the pit;The displacement of the top of the retaining wall on the north side changes slightly,and the horizontal displacement of the top of the other retaining walls develops towards the pit,while the vertical displacement first rises and then sinks;There is a positive correlation between the axial force of the support and the horizontal displacement of the wall top;Restricted by the space of the site,the surface monitoring settlement value increases gradually with the increase of the distance between the sides of the foundation pit;Benefiting from the construction strategy of sub-pit excavation and the isolation effect of MJS(Metro Jet System)piles,sub-pit B3-1-2 excavation has little impact on Line 1;Tunnel grouting technology can effectively control the development of tunnel settlement and lateral displacement.The research results can provide engineering reference for the design,construction and monitoring of relevant deep foundation pit projects.