软土地层邻近隧道深基坑变形控制设计分析与实践

Design and Application of Deformation Control Techniques for Deep Foundation Pits Adjacent to Existing Tunnels in Soft Soil

结合近年来在软土深基坑领域的工程实践和研究,阐述邻近隧道深基坑变形控制设计方法,主要包括基于微小变形控制分区设计、轴力自动补偿钢支撑、坑内土体加固、坑外隔断以及承压水控制设计方法等,通过实际工程案例分析不同设计方法在控制基坑与隧道变形方面的效果。同时,针对基坑开挖对邻近隧道影响评估难的问题,结合上海软土地层工程实践,介绍小应变本构模型(HS-Small)全套参数的确定方法以及基于小应变本构模型的基坑对隧道影响的数值分析方法。大量的工程实践表明,综合采取上述设计和分析方法能够有效评估基坑开挖对隧道的影响,并达到良好的变形控制效果,能满足地铁及隧道变形控制和结构安全的要求。

First, the design methods regarding deformation control and deep foundation pits adjacent to tunnels are introduced. These include zoned design based on small deformation control, steel support with force automatic compensation system, soil improvement in foundation pits, isolation method, and confined water control and design method. Second, case studies are used to analyze the deformation control effect of various methods in foundation pits and adjacent tunnels. Finally, the determination of parameters for the hardening of a small strain soil(HS-Small) model of Shanghai soft clay is presented. The application of finite element analysis using the HS-Small model to evaluate the influence of excavation on adjacent tunnels is reported. The application results show that the methods recommended can effectively evaluate the influence of the foundation pit excavation on adjacent tunnels. The deformation control effect is good, indicating their feasibility in deformation control and the safety guarantee of foundation pits and adjacent tunnels.