西堠门公铁两用大桥主桥主墩基础施工关键技术  

Key Construction Techniques for Main Pier Foundations of Xihoumen Rail-cum-Road Bridge

作　　者：张敏[1] 王东辉[1] ZHANG Min;WANG Donghui(China Railway Major Bridge Engineering Group Co.,Ltd.,Wuhan 430050,China)

机构地区：[1]中铁大桥局集团有限公司,湖北武汉430050

出　　处：《桥梁建设》2023年第6期1-9,共9页Bridge Construction

基　　金：中国国家铁路集团有限公司科技研究开发计划项目(P2022G054);中国中铁股份有限公司科技研究开发计划项目(2019-专项-01)。

摘　　要：甬舟铁路西堠门公铁两用大桥主桥为主跨1488 m的斜拉-悬索协作体系桥,公铁平层布置。5号主墩采用18根∅6.3 m超大直径钻孔桩基础,4号主墩采用双壁圆筒形嵌入式设置沉井基础(外径58 m、高37 m)。结合桥位处复杂海洋环境和主体结构特点,5号主墩基础采用导管架式深水栈桥+自浮式钢桁架钻孔平台方案施工,4号主墩基础采用板凳式栈桥+设置沉井方案施工。5号主墩超大直径钻孔桩施工时,设置深水栈桥(采用整体式导管架法建设),自浮式钢桁架钻孔平台(由钢桁架及钢锚桩组成)在船坞整体制造;浮运到桥位后,钻孔桩采用旋挖钻机分级成孔、全回转钻机全断面一次成孔,水下桩基混凝土采用双导管法灌注,解决了深水、浪涌及硬质裸岩下超大直径桩施工难题。4号主墩钢沉井结构在船坞整体制造,整体浮运到桥位后,首先通过定位系统(共设置12个混凝土重力锚)快速定位,然后对平面位置、高程和垂直度进行精确定位,解决了复杂海况下钢沉井整体浮运、精准定位及下沉着床难题。The main bridge of Xihoumen Rail-cum-Road Bridge of the Ningbo-Zhoushan Railway is a hybrid cable-stayed suspension bridge,featuring a main span of 1488 m and accommodating road and rail traffic on the same deck.To address the complex marine environments and the structural characteristics of the bridge,the main pier No.4 is supported by a double-walled circular caisson foundation measuring 58 m in external diameter and 37 m in depth,during the construction of which,a bent type trestle was installed and the river floor was consolidated before the settlement of the caisson.While the main pier No.5 is supported by 18 bored piles of 6.3 m diameter,during the construction,a deepwater trestle composed of integral steel pipe frames and a steel truss floating dock were installed.The steel truss floating dock,which was formed of steel trusses and steel anchor piles,was manufactured integrally in a shipyard and floated to the bridge site.To make the construction of large-diameter bored piles possible in the deep offshore area where the surges and hard rocks imposed great obstacles,the boreholes were drilled by the rotary drilling rigs in steps,subsequently the boreholes took shape while using casting rotators for cross-section treatment,and the pile concrete was cast by double-tremie-pipe method.Transported to the bridge site,the integrally pre-fabricated steel caisson of the main pier No.4 was rapidly positioned by a positioning system consisting of 12 concrete gravity anchors,then,the plane location,elevation and perpendicularity of which were adjusted.The construction of the caisson foundation was smooth and efficient.

关 键 词：公路铁路两用桥 斜拉-悬索协作体系桥 超大直径钻孔桩 嵌入式设置沉井 深水栈桥 自浮式钻孔平台 定位技术 施工技术 

分 类 号：U448.121[建筑科学—桥梁与隧道工程] U445.4[交通运输工程—道路与铁道工程]