全预制盾构隧道边箱涵精细化施工分析

依托京张高铁清华园隧道工程,介绍清华园隧道工程及其隧道内边箱涵施工工法,并详细讨论边箱涵预制化施工的优缺点。盾构隧道采用全预制轨下结构有5大优点:降低施工现场环境污染,有效改善施工现场工人作业环境,有助于提高工程整体施工效率,降低施工作业风险水平,保障钢筋混凝土构件的质量水平。但依然存在以下缺点:提升构件制造及运输维护费用,构件现场吊装精度要求较高。针对清华园隧道边箱涵吊装施工精细化施工问题进行有限元分析,发现由于边箱涵重心两侧吊装孔距不同,会导致边箱涵近重心侧产生应力集中现象,同时将随着吊装误差的提高应力集中现象显著提升。为保证边箱涵的精细化施工,边箱涵吊装误差不得超过60 mm,两侧边箱涵左右交错拼装施工,建议未来类似工程中异形构件吊装孔设计应考虑吊装误差产生的影响。

Analysis of Precision Construction of Side Box Culvert of Full Prefabricated Shield Tunnel

Based on the Tsinghuayuan Tunnel Project of Beijing-Zhangjiakou High-speed Railway, this paper introduces the Tsinghua Park tunnel project and the construction method of the box culvert inside the tunnel, and discusses in detail the advantages and disadvantages of the prefabrication construction of the side box culvert. The full prefabricated rail structure adopted by the shield tunnel has such five major advantages as reducing the environmental pollution on the construction site, effectively improving the working environment of site workers, helping to improve the overall construction efficiency of the project, reducing the risk of construction operations, and ensuring the quality of reinforced concrete members. However, the following shortcomings still exist: high manufacturing cost of the lifting component and high transportation maintenance cost, and high requirement for the accuracy of lifting component on site. In this paper, the finite element analysis of the hoisting construction of the box culvert in the Tsinghuayuan Tunnel is carried out and it is found that due to different hoisting distances on both sides of the center of the box culvert, stress concentration of the side culvert occurs near the center of its gravity, and intensifies remarkably with the increase of hoisting error. In order to ensure the precision construction of the side box culvert, the hoisting error of the side box culvert should not exceed 60 mm, and the left and right sides box culverts are staggered and assembled. It is suggested that the influence of hoisting error should be considered in the design of hoisting hole of special shaped components in similar projects.