盾尾刷更换时环形冻结加固结构温度场数值分析

Numerical Analysis of Temperature Field of Annular Frozen Reinforced Structure When Shield Tail Brush is Replaced

盾构法修建城市地铁隧道时,盾尾刷更换过程中的防渗漏问题一直是盾构隧道施工的关注重点。针对传统冻结加固保护盾尾刷方法的弊端,提出了使用环形冻结管加固止水保护盾尾刷更换的施工方法,通过有限元软件建模,分析比较布置1根环形冻结管和2根环形冻结管的冻结效果,从而确定出最佳冻结方案。结果表明:布设1~2根环形冻结管方案下数值计算结果均满足冻结加固范围和设计要求;为提高封水性与安全性及增大冻结加固止水范围,延长积极冻结时间不如增加环形冻结管的根数,且适当增加环形冻结管的间距有利于增强冻结效果;增加环形冻结管的根数可极大地提高盾尾处的冻结效果且有很高的安全系数富裕,分析结果可为相关施工工程提供一定的参考依据。

When shield tunnel is built by shield tunneling,the problem of seepage prevention during the replacement of shield tail brush has always been the focus of shield tunnel construction.In this paper,according to the disadvantages of the traditional method of the tail brush of the protection shield strengthened by freezing,the construction method of replacing the tail brush of the protection shield strengthened by the ring freezing pipe was put forward,and the freezing effect of one ring freezing pipe and two ring freezing pipes was analyzed and compared through the finite element software modeling,so as to determine the best freezing scheme.The main results are as follows:when the tail brush of the shield is replaced,the ring freezing reinforcement method can deal with sudden accidents;this construction method makes the replacement process of the tail brush of the shield safe and reliable.The numerical calculation results under the plan of laying 1~2 annular freezing pipes all meet the freezing reinforcement range and design requirements.In order to improve water sealing and safety and increase the freezing area,it is better to increase the number of roots of the ring freezing pipe than to extend the active freezing time.Increasing the number of roots of the annular freezing pipe can greatly improve the freezing effect at the end of the shield and have a high safety coefficient.