上跨电气化铁路系杆拱桥吊杆更换技术

Replacement Technology of Suspenders for Tied-Arch Bridge over Electrified Railway

顺河高架系杆拱桥为长90 m的下承式拱桥,是连接济南市南北交通的干线,并跨越胶济铁路济南东站西侧交通要道。检测发现该桥吊杆存在不同程度的损伤,需全部更换。新吊杆采用GJ15-19型环氧钢绞线整束挤压式吊杆,内部钢绞线采用5层隔离防腐,以提高耐久性。桥梁跨越高铁等电气化线路,下部作业空间受限,施工窗口期短,采用配置转换梁的抱箍式临时兜吊系统和梁底移动式挂篮更换吊杆。抱箍式临时兜吊系统张拉端设置在拱肋与桥面之间,避免了施工对公路交通的影响,且抱箍可拆卸重复利用;转换梁和梁底移动式挂篮克服了梁下作业空间小的难题,实现了铁路运营零干扰的目标。吊杆更换时首先安装临时吊杆实现第一次荷载转移后拆除原吊杆,然后安装新吊杆实现第二次荷载转移,全桥吊杆更换完成后进行全桥调索,最后进行新吊杆防腐和临时吊杆拆除。吊杆更换后桥梁受力状态良好,桥面线形满足设计要求。

The Shunhe Viaduct is a through tied arch structure crossing a vital railway west of the Jinan East Station of Jiaozhou-Jinan Railway.The viaduct is 90 m long,which is on an arterial route that serves the south-north traffic of the city.The inspections had revealed different degrees of damages of the suspenders,consequently it was determined to replace all the suspenders.The new suspenders are composed of GJ15-19 epoxy-coated extruded strands,and the inner steel strands are coated with five corrosion protection layers,to improve durability.Due to that the viaduct crosses a high-speed railway(electrified railway),the construction space beneath the deck is quite limited,and the window time for construction is short,an enclosure-type temporary suspension system with switch beams and form travellers moving underneath the deck soffit are employed for suspender replacement.The live end of the enclosure-type temporary suspension system is set between the arch rib and the deck,to avoid the disturbance of construction to the roadway traffic,and the enclosure can be demolished for reuse.The switch beams and form travellers moving underneath the deck soffit are good solutions for the limited construction space under the deck,which help achieve the goal of null disturbance to the railway operation.During replacement,temporary suspenders were first installed to realize the load transfer for the first time and then the old suspenders were able to be demolished.Afterwards,the new suspenders were installed to realize the load transfer for the second time.After the completion of replacement of all the old suspenders,the new suspenders were adjusted.Subsequently,the new suspenders were coated for corrosion protection and the temporary suspenders were removed.After the suspender replacement,the load bearing behavior of the viaduct is sound and the deck alignment meets the design requirements.