地铁盾构小净距上穿既有线变形数值模拟及施工控制
汤新辉1雷涛2刘维正3艾国平2戴晓亚3郭建明2
Deformation Numerical Simulation and Construction Control for Metro Shield Overpassing Existing Line in Smallclearance
TANG XinhuiLEI TaoLIU WeizhengAI GuopingDAI XiaoyaGUO Jianming
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作者信息:1.长沙市建设工程质量安全监督站， 410023， 长沙
2.中交一公局集团有限公司， 100024， 北京
3.中南大学土木工程学院， 410075， 长沙
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Affiliation:Changsha Construction Project Quality and Safety Supervision Station, 410023, Changsha, China
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关键词:
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Key words:
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DOI:10.16037/j.1007-869x.2023.09.014
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中图分类号/CLCN:U455.43
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栏目/Col:研究报告
摘要:
新建地铁施工时，不可避免地会对既有线路周围的地层产生扰动，使既有线路产生一定的变形，进而引发一系列病害问题。为保证既有线路的安全运营，需研究地铁盾构上穿施工引发的既有线路位移变形规律。方法：以长沙轨道交通6号线盾构小净距上穿长沙轨道交通3号线为例，采用FLAC3D软件建立三维数值模型，分析了盾构上穿既有线路过程中，既有线路的竖向变形发展规律，以及环形加固控制措施的加固效果。结果及结论：既有地铁隧道受影响的主要区域为既有隧道和新建隧道的水平投影交叉点附近；当新建盾构隧道施工距离既有隧道左右各120 m范围内时，其对既有隧道的影响较大，在此范围内施工时需要着重控制既有隧道的上浮变形；建议加固环数为5环；环形加固结构不改变既有隧道的竖向位移分布规律，可将管片的最大竖向变形降至11 mm；加固后，既有线拱顶处的最大竖向位移仅为13 mm，拱腰处的最大水平位移仅为14 mm，各监测断面的位移值均较小；所采取的施工控制措施能够有效减少新建线上穿施工对既有线造成的施工扰动，保证施工安全。
Abstracts:
During new metro line construction, unavoidable disturbances are generated in existing line surrounding stratum, causing certain level of deformation to existing line and subsequently causing a series of disease problems. To ensure existing line safe operation, it is necessary to study the law of existing line displacement and deformation induced by metro shield tunnel overpassing construction. Method: Taking Changsha Rail Transit Line 6 shield tunnel overpassing Line 3 in small clearance as example, a threedimensional numerical model is established using FLAC3D software. In the above overpassing process, the existing line vertical deformation development law and the reinforcement effect of circular reinforcement control measures are analyzed. Result & Conclusion: The main affected area of the existing metro tunnel is in the vicinity of the horizontal projection intersection point between the existing and new tunnels. The impact on existing tunnel is significant when the construction distance between the new and existing shield tunnels is within 12.0 meters on each side. Therefore, during construction in this range, it is necessary to focus on controlling the uplift deformation of existing tunnel. It is recommended to use 5 reinforcement rings. The circular reinforcement structure does not change the distribution law of the existing tunnel vertical displacement but can reduce the maximum vertical deformation of the segment to 1.1 mm. After reinforcement, the maximum vertical displacement at existing line arch crown is only 1.3 mm, and the maximum horizontal displacement at the arch waist is only 1.4 mm, with small displacement values observed at all monitoring sections. The adopted construction control measures effectively reduce the construction disturbance caused by the new tunnel overpassing existing line engineering, ensuring the construction safety.
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