甬舟铁路金塘水道双悬索桥方案共锚碇深水基础研究

甬舟铁路金塘水道主航道桥研究两大跨共锚碇钢桁梁悬索桥方案,孔跨布置为(112+224+1050+238+42) m+(42+238+980+336+84) m。桥址位置台风频发、水深流急、浪大潮高、地质复杂、航道众多,为适应共锚碇基础荷载大,建设环境复杂等条件,从结构受力、经济性、可实施性、水流适应性等方面对大直径钻孔桩基础、复合基础和沉井基础进行方案比选。研究结果表明:复合基础结构紧凑、刚度大,施工周期较短、风险低,但其防冲刷性能、受力特性等需开展系列专题试验研究验证,沉井基础相对成熟且在结构受力、工程造价、施工工期等方面均优于钻孔桩基础方案;圆形沉井和矩形沉井工程造价及施工周期基本相当,考虑到圆形沉井方案对水流适应性好,冲刷深度小,经综合比较共锚碇基础推荐采用圆形沉井基础方案。

Scheme Research of Deep Water Sharing-Anchorage Foundation of Double Suspension Bridge on Jintang Channel of Ningbo-Zhoushan Railway

For the main channel bridge of Jintang sea-crossing bridge on Ningbo-Zhoushan Railway, the schemes of the steel truss girder suspension bridge with two spans sharing the anchorage are studied, and the span of the bridge is arranged as(112+224+1050+238+42) m+(42+238+980+336+84) m. The bridge is located at a place with frequent typhoons, deep and fast water flows, high waves, complex geology and numerous channels. In order to adapt to the local condition of large anchorage foundation load and complex construction environment, this article compares the schemes of large-diameter bored pile foundation, composite foundation and open caisson foundation in terms of structure stress, economical efficiency, practicability and flow adaptability. The results show that the composite foundation structure is compact and rigid with short construction period and low risk, but its anti-scouring performance and stress characteristics need to be verified by a series of special tests. The caisson foundation is relatively mature and superior to the bored pile foundation scheme in structural stress, engineering cost and construction period. Though the cost and construction period of circular caisson and rectangular caisson are basically the same, the circular caisson foundation scheme is recommended due to its good adaptability to water flow and small scouring depth.