高速公路上跨电气化铁路立交桥换梁工程设计施工

Design and Construction of Beam Replacement for an Expressway Overpass Spanning Electrified Railway

唐津高速公路北环立交桥上部结构采用25 m后张预应力空心板梁,全桥共36跨总长890 m,其第20孔上跨北环双股电气化铁路,常规检查发现该跨板梁跨中梁底范围普遍存在横向裂缝,急需对该跨板梁进行更换。通过分析认为原桥设计标准偏低、近年来超载车辆激增、板梁间横向联系较弱为病害主要原因。针对病害原因,采用提高板梁荷载设计等级、增加梁高、增配普通钢筋和预应力钢筋、改变板梁间铰缝形式等措施设计新板梁。换梁施工采用切割机沿顺桥向切割板梁,用架桥机吊装新梁,并在施工过程中对铁路进行电气化防护。

The superstructure of the North Ring Road Overpass on Tangshan-Tianjin Expressway employs the 25-m span post-tensioned hollow slab beams.The whole overpass has 36 spans of the beams and is totally 890 m in length,of which the 20th span of the beam spans the double-track electrified railway.It was found from the regular inspection that in the underside of the midspan of the beam,the transverse cracks extensively existed and it was deemed urgently necessary that the beam should be replaced.The analysis revealed that the major cause leading to the crack deterioration of the beam could be attributed to the relative low design standard for the original overpass,the dramatic increase of overload vehicles on the overpass in the recent years and the rather weak transverse tie between the beams.In view of the cause of the deterioration,a new hollow slab beam was designed to replace the old one by taking a series of measures,such as improving of the load design grade of the beam,increasing of the beam depth,adding of the common reinforcement and prestressing tendons and changing of types of the hinged joint between the beams.In the process of the beam replacement construction,the original beam was cut off by the cutting machine in the longitudinal direction of the overpass,the new beam was lifted and erected by the overhead launching gantry and the electrified railway under the overpass was well protected all the time in the construction.