温州瓯江北口大桥主桥总体设计及结构选型

温州瓯江北口大桥为高速公路和普通国道合建的通道,结合建桥条件对该桥主桥进行总体设计及结构选型。受通航孔位置、净空尺度控制,综合考虑防洪影响、结构受力和施工难度等因素,主桥采用主跨2×800m的三塔悬索桥。南边缆跨跨径为348m,北边缆跨设置6根背索,跨径为230m,两边跨均采用悬吊结构。选取平层合建和双层合建两种加劲梁方案进行比选,最终采用结构受力合理、建设难度较低的双层钢桁梁方案。为解决中塔主缆抗滑移的技术难题,该桥中塔选取整体结构刚度大、抗风稳定性好的纵向A形混凝土塔,并采用设置竖向摩擦板的中主索鞍。中塔基础采用整体性和稳定性好、能承受船舶直接撞击作用的沉井基础。边塔采用H形混凝土塔,钻孔灌注桩基础。南、北锚碇均采用安全可靠的重力式锚碇,北锚采用扩大基础,南锚采用大型沉井基础。

Overall Design and Structural Selection of Main Bridge of Oujiang River North Estuary Bridge in Wenzhou

The Oujiang River North Estuary Bridge in Wenzhou provides a joint passage for expressway and ordinary national highway. The overall design and structural selection of the main bridge are carried out in combination with the conditions of bridge construction. Controlled by the location of navigation holes and clearance scale, a three-tower suspension bridge with a main span of 2×800 m is adopted for the construction of the main bridge after factors such as flood control, structural stress and construction difficulty being taken into account. The span of the side cable at the south is 348 m, and the side cable at the north is equipped with six back cables, with a span of 230 m. Suspension structures are used for both side spans. Two kinds of stiffening girder schemes for flat-layer joint construction and double-layer joint construction are selected for comparison and selection. Finally, a double-layer steel truss girder scheme with reasonable structural stress and low construction difficulty is adopted. Moreover, in order to solve the technical problem of anti-slip of the main cable at the middle tower, a longitudinal A-shaped concrete tower with high stiffness and good wind stability is selected in the middle tower of the bridge, and middle main cable saddle with vertical friction plate is adopted. The open caisson foundation with good integrity and stability which can withstand the direct impact of ships is adopted for the construction of the foundation of the middle tower. An H-shaped concrete tower and bored pile foundation are adopted in the construction of the side towers. Safe and reliable gravity anchorage is used in both south and north anchorage, enlarged foundation is used in north anchorage, and large open caisson foundation is used in south anchorage.