芜湖长江三桥施工浮桥设计

Design of Floating Bridge Built in Construction of Third Wuhu Changjiang River Bridge

芜湖长江三桥主桥桥墩均位于水中,需搭设施工浮桥用于水中墩施工混凝土输送及人员通行。芜湖侧浮桥布置于5号墩和3号桥塔墩之间,长272.3 m,跨径布置为(35.5+6×36+18)m,桥面净宽3.3 m。浮桥设计采用“浮箱+贝雷梁”结构,横向布置4榀贝雷梁,桥面板采用I10@750 mm分配梁+6 mm厚花纹钢板组成,桥面两侧设置混凝土泵管,人行道布置于混凝土泵管之间;共设7个浮箱,单个普通浮箱长12 m,宽6.1 m,由3根∅2000 mm×8 mm钢管焊接组拼而成,浮箱两端钢管切割成尖端型以减小浮箱所受水流力,最中间浮箱长度设计为24 m,并在浮箱上、下游侧布设混凝土锚碇以提高浮桥整体稳定性。通过在顺水流方向设置预偏量以及水位变化时收放锚绳等措施,确保了在大桥建设期间施工浮桥安全稳固。

All the piers of the main bridge of Third Wuhu Changjiang River Bridge are river piers.During the construction of these piers,floating bridges had to be built as personnel access and for the ease of concrete transportation.The Wuhu-side floating bridge was built between pier No.5 and pylon pier No.3,which measured 272.3 m long and 3.3 m wide,with span arrangement of 35.5 m,6×36 m and 18 m.The main components of the floating bridge incorporated the floating boxes and bailey trusses,along the width,four bailey trusses were installed side by side.The deck system was formed by distribution beams(I10@750 mm)and 6 mm-thick checkered plates.Concrete pump pipes were placed along the two sides of the deck,and the space in between was footway.A number of 7 floating boxes were used,each measuring 12 m long and 6.1 m wide.The floating boxes were linked by three steel tubes with dimensions of∅2000 mm×8 mm.At the two ends of the floating box,the steel tubes were cut to have pointed ends so as to reduce flow force.The central floating box was 24 m long,on both the upstream and downstream sides of which,concrete anchorages were built to improve the global stability of the floating bridge.In addition,the central floating box was also set with pre-displacement along the flow direction to ensure the safety and stability of the floating bridge during construction.When the water level showed fluctuation,the anchor ropes could be loosened or tautened for the same purpose.