深水基础自锚式悬索桥设计与施工

Design and Construction of Self-Anchored Suspension Bridge with Deepwater Foundations

青田前仓大桥主桥为(45+120+45)m预应力混凝土自锚式悬索桥,半飘浮约束体系,是国内水深最大的自锚式悬索桥。该桥的创新如下:桥塔基础采用大直径嵌岩钢管混凝土桩,解决了深水裸岩基础桩基定位及成孔问题,形成的钢-混凝土组合结构提高了桩基的承载力;采用无应力状态法作为自锚式悬索桥体系转换控制方法,解决了分阶段张拉自锚式悬索桥的安装计算和施工控制问题,提高了施工效率和控制精度。

The main bridge of Qiancang Bridge in Qingtian County,is a prestressed concrete self-anchored suspension bridge with spans of(45+120+45)m and the largest water depth in China.The bridge has a half floating system.The ground setting of the tower features bare bedrocks,specifically the 1m thick gravel overlying the intermediary-weathered granite that can served as the bearing stratum.The maximum water depth reaches 27.5m,which makes this bridge as the self-anchored suspension bridge with the largest water depth in China.The large diameter concrete-filled steel pipe piles to be built into rocks are selected for the tower foundations,which is very innovative.It solves the problem of pile foundation positioning and hole formation in deep-water&bare-rock foundations,and the formed steel-concrete composite structure greatly improves the bearing capacity of the pile foundation.The method of stress-free status is used as the system conversion control method of the self-anchored suspension bridge,which solves the problems of the installation calculation and construction control of the self-anchored suspension bridge tensiled in stages,and greatly improves the construction efficiency and control accuracy.