传统暗挖施工方法难以在含水量高、承载力低的饱和软土地层适用，管幕暗挖法可为软土地层暗挖施工提供新的途径。目前管幕暗挖法设计和施工经验不成熟，工程实施难度大，施工过程风险控制尤为重要。为此，结合上海市轨道交通14号线桂桥路站管幕段工程实例，从风险管控角度论述管幕暗挖法施工过程中管幕顶进精度、MJS加固地内压力控制、内衬墙倾覆、融沉注浆、开挖过程中坍塌和涌水等风险因素，并提出相应对策。研究结果表明： 1）在软土地层进行管幕暗挖法施工大断面地下空间是可行的，施工风险总体可控； 2）管幕顶管顶进工序是管幕暗挖法实施的基础，开挖支撑是该工法施工风险控制的关键工序，同时也是造成地面沉降的主要工序。
The traditional underground excavation method can
hardly be applied to the saturated soft soil with high water content and low
bearing capacity, while the piperoof undercutting method
provides a new way for soft soil excavation construction. At present, the
design and construction experience of piperoof
undercutting method are not mature, which leads to great difficulty. The risk
control is particularly important during construction. Hence, based on the
engineering practice of the piperoof section of
Guiqiao Road Station on Shanghai Metro Line No. 14, some risk factors such as
advancing precision of piperoof, MJS reinforced
underground pressure control, lining wall overturning, melting and grouting,
collapse and water gushing during excavation are discussed from the perspective
of risk control, and the corresponding countermeasures are put forward. The
analytical results show that: (1) It is feasible to construct large crosssection underground space by piperoof
undercutting method in soft soil, and the construction risk is generally
controllable. (2) The jacking process is the basis for the implementation of
piperoof undercutting method, the process of
excavation and support is the key process for the construction risk control and
also the main factor causing ground subsidence.
