超浅埋隧道下穿运营铁路新工法研究及应用  

Study on Novel Methodology for Ultra-shallow TunnelConstruction underneath Operational Railways and Application

作　　者：陈力 焦康杰 CHEN Li;JIAO Kangjie(Shanghai Urban Construction Design&Research Institute(Group)Co.,Ltd.,Shanghai 200125,China;Guiyang Survey and Design Co.,Ltd.of CREEC,Guiyang 550002,China)

机构地区：[1]上海市城市建设设计研究总院(集团)有限公司,上海200125 [2]中铁二院贵阳勘察设计研究院有限公司,贵阳550002

出　　处：《高速铁路技术》2024年第5期113-118,124,共7页High Speed Railway Technology

摘　　要：随着我国铁路的快速发展,新建浅埋暗挖隧道下穿既有运营铁路常有涉及,新建隧道施工严重威胁铁路运营安全,保障隧道施工安全与既有线运营安全是亟待解决的问题。本文以西南地区某铁路隧道下穿运营铁路工程为背景,提出“短循环,三次衬砌截桩”新工法,通过衬砌结构验算、三维数值模拟及工程应用进行研究。结果表明:(1)在超浅埋隧道小角度下穿运营铁路工程中,该工法使得D型便梁可自由组合,摆脱了D型便梁长度受限的束缚;(2)三次衬砌不仅提高了永久支护结构的安全系数,而且解决了隧道防水问题;二次、三次衬砌的最小安全系数均位于拱顶,分别为5.8和14.9,均满足规范要求;(3)隧道从两端向中间掘进,初期支护拱顶沉降曲线呈现出中间小两端大的“Λ”形态,最后贯通的8 m围拱顶沉降最小;(4)待二次衬砌达到设计强度100%后再进行人工截桩施工,可以减小因桩体支撑点的改变所引起的隧道拱部沉降量;(5)该工法通过短开挖及时支护控制隧道应力释放,进而减小地层损失所引起的地表沉降对运营铁路的轨道变形影响。经过5年跟踪调查,该工程未发现衬砌裂缝及渗漏水等病害,充分验证了该工法的安全可行性。Amidst the rapid expansion of China’s railway network,the construction of new shallow tunnels that cross beneath existing operational railway lines is increasingly common,posing significant threats to the safety of both tunnel construction and railway operations.Based on the construction of a railway tunnel,this study introduced a novel“short cycle,three-stage lining with pile cutting”approach.Through the examination of lining structure calculations,three-dimensional numerical simulations,and practical applications,the following conclusions are drawn:(1)In ultra-shallow tunneling projects involving small-angle crossings beneath operational railways,this methodology enables flexible assembly of D-type temporary supports,overcoming limitations imposed by fixed D-type beam lengths.(2)The three-stage lining not only enhances the safety factor of the permanent support structure but also addresses waterproofing concerns.The minimum safety factors for the secondary and tertiary linings,respectively located in the arch crown,are found to be 5.8 and 14.9,both meeting regulatory requirements.(3)Excavation progresses from both ends towards the middle,resulting in a“Λ”shaped profile of initial lining vault settlement,with the smallest settlements occurring in the final 8 m stretch before breakthrough.(4)Undertaking pile cutting after the secondary lining reaches 100%design strength mitigates tunnel vault settlement caused by changes in pile support points.(5)The method effectively manages stress release through short excavation cycles and prompt support installation,thereby minimizing ground settlement-induced railway track deformation due to ground loss.A five-year follow-up investigation reveals no instances of lining cracks or water ingress,substantiating the safety and feasibility of the proposed methodology.

关 键 词：浅埋隧道 下穿铁路 新工法 数值分析 工程应用 

分 类 号：U455[建筑科学—桥梁与隧道工程]