杭台铁路椒江特大桥主桥施工监控

Construction Monitoring of Main Bridge of Jiaojiang River Bridge of Hangzhou-Taizhou Railway

杭台铁路椒江特大桥主桥为主跨480 m的双索面、双主桁钢桁梁斜拉桥,主梁采用边跨顶推、中跨悬臂吊装的总体方案施工。为使成桥线形、结构内力满足设计要求,保证主桥施工过程安全,根据总体施工方案,采用MIDAS Civil软件建立主桥施工过程计算模型进行结构正装计算分析;根据无应力状态法,中跨悬臂吊装阶段按照“线形控制为主、索力控制为辅”的原则进行施工控制,中跨合龙后按照“线形、索力双控”的原则进行施工控制。结果表明:中跨合龙最大误差6 mm,采取纠偏措施后实现了精准快速合龙;与设计成桥状态相比,成桥线形误差控制在4 cm以内,成桥斜拉索索力误差控制在±5%以内,结构线形、索力均满足设计要求。

The main bridge of Jiaojiang River Bridge of Hangzhou-Taizhou Railway is a cable-stayed bridge with a main span of 480 m.The stay cables are fanned out in double cable planes.The superstructure consists of two lateral trusses,where the trusses in the side spans were erected by incremental launching method,while the trusses in the central span were erected by cantilever hoisting and assembly.To make sure that the as-built alignment and internal forces of the bridge could meet the design requirements and guarantee the construction safety,the construction process of the main bridge was numerically simulated by MIDAS Civil in accordance with the construction scheme,and the regular-order installation of the structure was analyzed.By the stress-free state method,the alignment was the key control focus during the cantilever hoisting and assembly of the central span,along with the stay cable forces monitoring.Once the central span was closed,both the alignment and stay cable forces were elevated as dominant control issues.In the Jiaojiang River Bridge,the calculated maximum alignment bias during the central span closure was 6 mm,after taking modification measures,the central span achieved rapid and accurate closure.Compared with the design alignment,the actual alignment bias was controlled within 4 cm,and the stay cable forces bias was controlled within the range of±5%,proving that the as-built alignment and the stay cable forces of the bridge meet the design requirements.