大跨径连续梁0号块托架结构设计及预压施工

Design of Corbels to Pier-Top Section of Long-Span Continuous Girder and Pre-loading Construction

郑万高铁汉江特大桥主桥为(109+220+109)m连续刚构-拱结构,主桥0号块为单箱双室结构,长度达22m,高达12m,混凝土方量约2209m3,重约5743.4t。0号块采用托架法施工,托架结构由][10楔形底模桁架、2HN45分配梁、主承重桁架、横向联结系、预埋件等组成。主承重桁架通过对拉杆和销轴固定在墩身上。托架所承受0号块施工荷载较大,为确保托架的施工安全,采用多点千斤顶反压法进行预压施工。托架预压分60%、80%、100%、110%四级进行,加载总重量为0号块悬臂段施工荷载的1.1倍。在预压加载过程中对托架沉降以及焊缝进行观测,结果表明托架的强度和刚度能够满足施工要求。

The main bridge of Hanjiang River Bridge on Zhengzhou-Wanzhou High-speed Railway is a combined continuous rigid frame and arch structure with spans of 109, 220 and 109 m. The pier-top section of the main girder is the two-cell single box structure, measuring 22 m long and 12 m high, weighing about 5 743.4 t and costing 2 209 m 3 concrete. The pier-top sections are constructed by using corbels. The corbels are formed of ][10 wedge base mould trusses, 2HN45 spreader beams, main load bearing trusses, lateral bracings and pre-embedded elements. The main load bearing trusses were fixed to the pier shafts by tie rods and pins. The corbels had to carry the construction loads of the pier-top girder sections, to ensure the construction safety of which, the pre-loading construction was carried out by reverse loading method, the pre-loading was applied by four stages of 60%, 80%, 100% and 110%, and the total loading amount was 1.1 times of the construction loads of the cantilevers of the pier-top sections. During the pre-loading process, the settlement of the corbels and the welding joints were monitored. The results show that the strength and rigidity of the corbels can meet the requirements of the construction.