柳州双拥大桥关键结构设计

Design of Key Components of Liuzhou Shuangyong Bridge

柳州双拥大桥为(40+430+40)m单主缆钢箱梁悬索桥。除靠近桥塔侧设置5对斜吊索外,其余位置均为直吊索。主梁梁高3.5m,采用流线型扁平式封闭钢箱梁,中间设置纵隔板,纵隔板既作为吊点受力构造又作为顶推支点。桥塔为三角形截面,采用全钢结构。钢塔与承台采用拉压式钢混连接结构,桥塔上横梁采用格栅结构满足主缆竖向力传递需要。两岸锚碇均为重力式锚碇,现浇扩大基础,使用散索套分散主缆,有效减小了锚碇埋置深度。锚碇基坑开挖采用了帷幕止水、设置连续板墙加支护桩等措施。通过分区域对锚碇基底进行处理,解决了锚碇基底承载力不足的问题。

The Liuzhou Shuangyong Bridge is a（40＋430＋40）m steel box girder suspension bridge with a single main cable.Besides the five pairs of inclined hanger cables close to the towers,the remaining ones are all vertical hanger cables.The main girder,with a depth of 3.5m,adopts stream-lined closed flat steel box girder,in the central of which longitudinal diaphragms that act as both the load bearing components at the hanging locations and the supports for pushing operation are installed.The tower is a steel structure with triangular cross section,connected to the pile cap by way of tensile-compressive steel-concrete connection.The upper cross beam of the tower adopts the grid structure which suits the demand of vertical force transmission in the main cable.The anchor blocks on both the banks are gravity anchors seated on cast in-situ spread foundations.The main cables are separated by splay saddles,effectively reducing the burying depth of the anchor blocks.During the excavation of the anchor block foundations,a series of measures were taken,such as the air curtain water stopping method,and erecting continuous plate walls and supporting piles.The base of the anchor blocks was divided into several regions during construction,so as to solve the problem of insufficient load bearing capacity of the anchor block base.