盾构隧道管片上浮机理与控制分析

Analysis of Mechanism and Controls of Segment Floating of Shield Tunnels

盾尾后方管片上浮是盾构法隧道施工过程中普遍存在的问题。本文针对南京地铁三号线TA-14标胜-天区间的盾构隧道施工过程中出现的管片上浮现象,分析了盾构隧道掘进过程中管片上浮的机理。从实测数据及受力分析入手,提出了管片上浮的两个阶段,其中第一阶段为管片上浮的主要时间段,在短时间内就完成了管片上浮总量的70%,为重点研究阶段。研究探讨了管片上浮量的决定性因素,认为改善水泥砂浆的初凝时间以及早期抗剪强度是有效控制管片上浮的重要措施之一。提出了施工过程中盾尾后方管片上浮的对策和针对性措施,可为今后类似盾构隧道施工提供参考。

The upward movements of segments at the rear of shield machine were a ubiquitous problem of shield tunneling construction. In this paper,taking TA-14 bid section of Nanjing Metro Line 3 as an engineering background,the mechanism of segment floating was analyzed. Based on the measured data and stress analysis,two-stage upward movements of segments were proposed and the determining factors of segment floating were also analyzed. Among them,the first stage is the main stage of segment-floating. In this stage,segments floating completed seventy percent of the total; we think that this stage is the key in the control of segment floating research. At the same time,we believe that the change of the cement mortar’s initial setting time and the shear strength in early age is one of the important measures to control the segments floating. In addition,countermeasure and suggestion for the upward movements of segments were proposed which could provide reference for future similar situations of construction of shield tunnels.