盾构隧道端头箱型冻结壁温度场演变数值优化分析

Numerical Optimization Analysis of Temperature Field Evolution of Shield Tunnel End Box Freezing Wall

为合理选择施工现场盾构隧道端头加固方式,本文针对盾构隧道端头箱型冻结这种新型加固方式,运用有限元软件分析箱型冻结壁加固结构温度场发展规律,并对其进行优化设计。研究表明:冻结40 d时可形成一个完整的箱型冻土帷幕,其冻结壁厚度最大约为2.12 m,平均温度在-10℃以下,平均厚度大于1.6 m,该工法可行。通过增加冻结管间距来减少冻结管的数量,优化对比3个冻结方案得出:冻结管间距在1.0 m变化范围内,冻结壁形成效果与原模型相似,冻结管间距为1.0 m时所用的冻结管数量较少,更具经济性,故冻结管间距1.0 m为最佳方案。通过分析冻结管间距和冻结40 d冻结壁厚度的关系,得出两者的变化呈线性相关。

In order to reasonably select the shield tunnel end reinforcement method at the construction site,in this paper,a new reinforcement method of shield tunnel end box freezing was selected,and the finite element software was used to analyze the temperature field development law of box freezing wall reinforcement structure,and the optimization design was carried out.Results showed that a complete box-shaped frozen soil curtain can be formed after 40 days of freezing.The maximum thickness of frozen wall was about 2.12 m,and the average temperature was below -10℃,and the average thickness was greater than 1.6 m.This method was feasible.By increasing the spacing of freezing pipes to reduce the number of freezing pipes,the optimization comparison of three freezing schemes showed that the freezing pipe spacing was within the range of 1.0 m,and the freezing wall formation effect was similar to the original model.When the freezing pipe spacing was 1.0 m,the number of pipes was less and it was more economical.Therefore,the freezing pipe spacing of 1.0 m was the best scheme.By analyzing the relationship between the spacing of freezing pipes and the thickness of freezing wall for 40 days,it was concluded that there was a linear correlation between them.