张靖皋长江大桥南航道桥南塔防撞方案研究

Research on Collision Protection Schemes of South Tower of South Navigation Channel Bridge of Zhangjiagang-Jingjiang-Rugao Changjiang River Bridge

张靖皋长江大桥南航道桥为主跨2300 m的双塔双吊跨钢箱梁悬索桥,桥下船舶通航密度大、船舶平均吨位大、船舶碰撞概率高、南塔所受船撞力计算值大。经综合分析,传统被动防撞方案均不能很好满足南塔防撞要求,故提出采用锁口钢管桩围堰外挂软体护舷的新型防撞方案。该防撞方案通过在承台外围设锁口钢管桩围堰形成裙墙,在围堰外侧外挂软体护舷,并在围堰与承台之间空隙处填充耗能材料实现防撞及消能,裙墙同时兼作临时施工围水设施以及起到永久冲刷防护和船撞消能作用。为验证新型防撞装置的防撞效果并选择合适的耗能材料,进行船桥碰撞有限元分析。最终采用填充沙粒的新型防撞装置方案,该方案可削减36.68%南塔承台撞击力,防撞效果好。新型防撞方案施工简单,后期仅需对钢管桩作防腐处理,撞后便于修复,工程造价低。

The south navigation channel bridge of Zhangjiagang-Jingjiang-Rugao Changjiang River Bridge is a two-tower,steel box girder suspension bridge,featuring its two unequal suspended spans,with the length of the main suspended span reaching 2300 m.The river traffic beneath the bridge is heavy,with a great portion of large-tonnage ships,thus increasing the ship impact risk of the south tower that stands in the river,and the calculated collision forces are big.Hanging soft fenders on the outer surface of the cofferdam comprising interlocking steel piles is recommended,which can fulfill the collision protection demands better than using the traditional passive collision protection measures.The interlocking steel piles cofferdam is placed to enclose the pile cap to be apron walls,upon which the soft fenders are hung,and energy dissipating material is filled in the gap between the cofferdam and the pile cap to achieve collision protection and energy dissipation.The apron walls also serve as water retaining facilities,as well as permanent scouring protection and ship collision energy dissipation structure.Ship-bridge collision simulation was conducted to verify the collision protection performance of the recommended collision protection structure and select proper energy dissipation material.It was determined to use sand to fill the gap between the apron walls and the pile cap,which can reduce 36.68%of the collision forces on the pile cap.The proposed collision protection structure is easy to be installed and quite economical in the future maintenance,and the only maintenance concern is to handle the corrosion of the steel piles.