绿汁江大桥大倾角隧道锚主缆预应力锚固系统定位技术  

Positioning Techniques for Prestress Anchoring System in Large-Inclination Tunnel Anchorages of Main Cables of Lvzhijiang Bridge

作　　者：陈健 CHEN Jian(The Fifth Engineering Co.,Ltd.,China Railway Major Bridge Engineering Group,Jiujiang 332004,China)

机构地区：[1]中铁大桥局集团第五工程有限公司,江西九江332004

出　　处：《世界桥梁》2024年第3期42-47,共6页World Bridges

摘　　要：绿汁江大桥为主跨780 m的单塔单跨钢箱梁悬索桥,玉溪岸隧道锚总长86 m,锚塞体底板与水平面夹角54°,主缆预应力锚固系统定位精度要求高达3 mm。针对锚固系统定位测量的重难点,分别采用精密导线法、双导线法布设洞外、洞内加密控制网;建立锚固系统数学模型,将隧道锚坐标系转换为整体坐标系,计算索股预应力管道坐标,并与软件建立的锚固系统三维几何模型中的坐标对比,经复核坐标转换结果准确。主缆预应力锚固系统随锚碇基础及填芯混凝土施工逐层安装定位,采用全站仪三维坐标法及精确修正球气差常数的全站仪三角高程差分法对测量高程进行修正。定位时,首先进行后锚面模板精调;接着基于锚垫板与索股预应力管道同轴调整原理,调整锚垫板与对应索股预应力管道轴线相垂直以及锚垫板的平整度,进行后锚垫板定位;然后安装定位支架,进行索股预应力管道定位;最后进行前锚垫板定位,实测锚固系统定位精度小于3 mm。Featuring a single suspended main span of 780 m,the Lvzhijiang Bridge is a steel box girder suspension bridge that has only one tower.The Yuxi-side tunnel anchorage measures 86 m in total length,the bottom of which inclines and forms an angle of 54°against the horizontal.The positioning accuracy of the prestress anchoring system of the main cables is required to be 3 mm.Considering the positioning challenges,encrypted control networks are distributed outside and inside the tunnel cavity using the methods of traversing and traversing on double lines,respectively.The mathematical model of the anchor system was established to convert the coordinate system of the tunnel anchorage into an integral coordinate system,in such a way to calculate the coordinates of the conduits of prestressing tendons,and the calculations were verified by 3D numerical simulation.The anchoring system was installed and positioned layer by layer,afterwards,the measured elevations were modified by the 3D coordinate method of total station and the trigonometric elevation difference method of total station that accurately corrects the spherical air difference constant.During positioning,the formwork of rear anchor surface was fine-tuned first,and the latter was positioned by adjusting the anchor plates to perpendicular to the axes of the conduits of prestressing tendons,as well as the flatness of the anchor plates,following the principle of coaxial adjustment of anchor plates and conduits.Subsequently,the conduits of prestressing tendons were positioned via positioning frames.At last,the front anchor plates were positioned,and the measured positioning accuracy of the anchor system was less than 3 mm.

关 键 词：悬索桥 大倾角隧道锚 锚固系统 加密控制网 坐标系转换 全站仪三维坐标法 施工测量 定位技术 

分 类 号：U448.25[建筑科学—桥梁与隧道工程] U443.24[交通运输工程—道路与铁道工程] U445.4