基坑工程对邻近地铁隧道影响的分析与对策

上海市闸北区大宁商业中心基坑东侧围护体距离已运行地铁隧道的最小净距仅为5.45 m。本文主要介绍了该工程中为控制隧道变形采取的设计技术措施:盆式开挖配合钢管斜坡撑代替大面积支撑、地铁侧坑内被动区采用水泥土搅拌桩加固和遵循时空效应原理的设计开挖工况等。同时针对本工程设计以变形控制为主的特点,采用了三维连续介质有限元法分析了开挖所引起的环境效应,其中土体采用修正剑桥模型模拟。同时采取了不同计算方案对比分析了采用抽条开挖的有效性,为设计和施工提供了有益的参考。

Analysis and countermeasures of influence of excavation on adjacent tunnels

The minimum distance between the east side of retaining structures of Daning Commercial Center and tunnel is just 5.45 m,technical measures were introduced to control the deformation of tunnel liner such as basin excavation combined with inclined steel strut to replace large-area strut,the reinforcement inside the foundation pit adjacent to tunnels by soil-cement mixed piles and designed excavation steps based on time-space effect.Since the control of deformation was the main purpose of the design in this project,3D continuous FEM method was used to analyze the environmental effect due to excavation,and the modified Cambridge clay model was used to simulate soils.At the meantime,the effectiveness of interval excavation was indicated by different calculation plans and the calculated results provided valuable reference to design and construction.