软土隧道盾构出洞灾害的渗流应力耦合分析

对盾构出洞口涌水涌砂灾害问题作了分析。利用Midas-GTS软件,建立了盾构出洞施工的有限元模型。考虑盾构出洞施工的渗流-应力耦合效应,研究了盾构工作井外加固土体前方高水位工况下,地下水绕加固土体下卧土层的渗流规律以及加固土体前方原状土的沉降规律。研究结果表明,在假定井外加固土体完全隔水情况下,洞门涌水涌砂灾害的发生与否受到土体加固长度、井外地下水等因素影响;土体加固长度的增加对工程安全有利,但成本较高;地下水位的降低能有效减小盾构出洞洞门涌水灾害的发生,需综合考虑工程安全性、经济性和工期等来确定合理的施工参数。

Analysis of coupled seepage and stress of shield tunnel launching accident in soft clay

The disaster causes of gushing water and sand during shield departure from shaft are analyzed; and the finite element model of shield departure construction is established using Midas-GTS software. Considering coupled seepage and stress of shield departure construction, the groundwater permeates from reinforced soil around underlying layer to wall is analyzed; and the settlement of the undisturbed soil in front of the reinforced soil is studied. An example is given to demonstrate that: supposing the reinforced soil is impervious, the accident that water and sand inflows from tunnel portal is influenced by length of soil reinforcement and groundwater level; increasing the length of reinforced soil is good for engineering safety; but the cost is high. Decreasing the groundwater level could reduce the disaster of gushing water and sand during shield departure from shaft. Reasonable construction parameters for a project are determined by taking into account of economy, security and time limit.