500 m级钢管拱桥成拱计算与控制方法

在大跨径的钢管混凝土拱桥中，钢管拱肋的斜拉扣挂成拱过程面临计算困难、大悬臂结构频繁调整、成拱状态偏离等难题。在成拱的理论计算方面，引入了基于无应力参数精确控制的成拱控制方法，明确了大跨径钢管拱斜拉扣挂施工过程控制目标。基于该控制方法，构建了钢管拱桥的成拱计算理论方法。该计算理论首次给出了钢管拱肋合龙前后的力学状态联系方程，建立了成拱后拱肋线形误差与施工过程索力的数学关系，构建了同时考虑施工全过程约束条件与成拱后线形偏差的一次调索优化模型。该一次调索优化模型可在任意给定的成拱线形误差范围和施工过程中的塔偏、封铰、合龙等耦合约束条件下，求解最优的扣背索一次张拉索力。在成拱施工控制方面，首次提出采用三维扫描技术进行大型钢管拱肋的无应力参数精确控制与检测方法，给出了详细的封铰控制、拱肋节段无应力参数控制和合龙控制的具体实施方法。在跨径为507 m的合江长江公路大桥的建设全过程,采用了所提出成拱计算理论与控制方法。实践表明:所提出的成拱计算理论具有控制目标少、计算目标明确、索力分布与张拉最优的优点；所提出的控制方法确保了钢管拱肋制造与安装无应力尺寸的精度，极大地减少了施工过程中拱肋线形误差调整次数。大桥拱肋成拱后实测结果表明，拱肋线形与应力状态与一次落架状态吻合良好。

Arch Forming Calculation Theory and Control Method of 500 m Steel Tube Arch Bridge

In the long-span concrete-filled steel tube arch (CFST) bridge, the process of forming the steel tube arch rib by cable-stayed buckle method is faced with difficulties in calculation, frequent adjustment of large cantilever structure, arched state deviation and so on. In terms of theoretical calculation of arching, the arch forming control method based on the precise control of unstressed parameters was introduced in this paper, and the control objectives of long-span steel pipe arch in the process of cable-stayed buckle construction were determined. Based on the control method, the theoretical method of arch forming calculation of steel tube arch bridge was established. In this calculation theory, the mechanical state connection equation before and after the closure of steel tube arch rib was given for the first time, the mathematical relationship between the arch rib linear error and the cable force during the construction process was established, and the one-time cable adjustment optimization model considering the constraints of the whole construction process and the linear deviation after the arch was constructed. The cable force optimization model can be used to solve the optimal cable force of buckle and back cable under any given linear error range after arching and coupling constraints such as tower deviation, hinge closure and closure during construction. In the aspect of arch forming construction control, the accurate control and detection method of non stress parameters of large steel tube arch rib using 3D scanning technology was proposed for the first time in this paper, and the detailed implementation methods of hinge sealing control, non stress parameters control of arch rib segment and closure control were given. In the whole process of the construction of Hejiang Changjiang River Highway Bridge with a span of 507 meters, the proposed arch forming calculation theory and control method were adopted. The practical results show that the proposed arch forming calculation theory has the advantages of less control objectives, clear calculation objectives, optimal cable force distribution and tension. The proposed control method ensures the accuracy of the non stress dimension in the fabrication and installation of the steel pipe arch rib, and greatly reduces the adjustment times of the arch rib linear error in the construction process. The measured results show that the alignment and stress state of the arch rib match well with the one-off state.