软土地区深基坑变形控制措施对减小临近隧道变形的效果分析

Effect analysis of the deformation control measures of deep excavation to reduce adjacent tunnel displacement in soft soil

临近地铁隧道的基坑工程有严格的变形控制要求,因此在基坑设计中如何预测隧道变形并提出有效的变形控制措施显得尤为重要。以毗邻宁波轨道交通1号线的宁波东部新城C1-5地块项目为例,通过Midas/GTS三维有限元软件就四种设计措施对临近地铁区间隧道位移控制的效果进行了对比分析。结果显示,采取坑内、外土体加固措施在减小基坑开挖导致的隧道位移方面效果明显,增加支护桩桩径对隧道水平位移控制比较有利,而增加支护桩桩长对隧道水平位移控制效果有限。研究成果可为软土地区轨道交通控制保护区内的深基坑工程的优化设计提供借鉴。

Due to the extremely strict requirement of deformation control for the excavation near the subway tunnel,it is very important to predict tunnel displacement and take effective control measures at the design stage. The effects of four measures to control the displacement of the subway tunnel are compared with Midas/GTS 3 D finite element software for the deep excavation of the C1-5 block in Ningbo Eastern New Town Project which is adjacent to the Ningbo Transit Railway Line 1. The results show that the effect of soil reinforcement inside and outside the pit to reduce the tunnel displacement caused by excavation is significant. The effect of increasing the diameter of the soldier pile to control the tunnel horizontal displacement is also significant. However,it is ineffective to increase the soldier pile length to minimize the tunnel horizontal displacement. The research results could provide reference for the optimal design of deep excavation in the rail traffic protection zone in soft soil area.