德江(合兴)~余庆高速公路乌江特大桥斜拉扣挂系统设计参数分析

Analysis of Design Parameters of the Cable-stayed Buckle System of Wujiang Major Bridge

目前,大跨度拱桥主拱普遍采用斜拉扣挂+缆索吊装的施工方法,该方法的核心是斜拉扣挂系统的设计与施工。通常而言,在一次张拉过程不调索的索力计算原则下,主拱拆索合龙后线形、扣背索索力变化、悬臂安装过程中主拱的挠度幅值及扣塔的纵向位移幅值,均受到扣背索角度以及扣塔刚度等设计参数的影响,并呈现一定规律。然而,少有文献对上述参数的影响进行分析。针对在建的德江(合兴)~余庆高速公路乌江特大桥,通过对各关键参数的比选分析,得出该桥斜拉扣挂系统的主要结构设计参数对线形、变形及内力的影响规律。研究结果表明,在一定的参数取值范围内,通过调整扣背索力均能满足主拱圈的合龙线形;拱顶及拱腰扣索水平倾角增大有利于减小主拱挠度幅值;可通过调整拱腰扣索水平倾角来减小扣塔纵向位移幅值;背索水平倾角改变只对背索索力产生影响。

At present,the main arch of long-span arch bridges generally adopts the construction method of cable-stayed buckle plus cable hoisting.The core of this method is the design and construction of the cable-stayed buckle system.Generally,under the principle of cable force calculation without adjusting the cable in the process of tensioning,the geometry of main arch after the cable is removed and closed,change of cable force of the buckle back cable,the deflection amplitude of the main arch and the longitudinal displacement amplitude of the buckle tower during the cantilever installation,are all affected by the design parameters such as the angle of the buckle back cable and the stiffness of the buckle tower,and present a certain rule,however,few documents have analyzed the influence of the above parameters.In this paper,based on the Wujiang Major Bridge of Dejiang(Hexing)-Yuqing Expressway under construction,through the comparison and analysis of the key parameters,the influence rules of the main structural design parameters of the cable-stayed buckle system on the alignment,deformation and internal force of the bridge are obtained.The research results show that,within a certain range of parameters,the closure alignment of the main arch ring can be satisfied by adjusting the buckle back cable force;the increase of the horizontal inclination of the arch crown and the arch waist cable is beneficial to reduce the deflection amplitude of the main arch;the longitudinal displacement amplitude of the buckle tower can be reduced by adjusting the horizontal inclination of the buckle cable at the arch waist;and the change of the horizontal inclination of the back cable only affects the back cable force.