东海大桥近岸浅海段桥墩PHC桩施工技术

Construction technique of PHC piles for offshore piers of Donghai bridge

东海大桥桥轴线全长31 km,近岸浅海段桥墩桩基采用PHC桩;近岸浅海段桥墩桩基的施工为远离岸线的无掩护外海施工,风大、浪高、流急,海况条件恶劣,全年有效作业天数仅为174 d;近岸浅海段桥墩桩基所处区域地质结构复杂、海水含盐量高。因此,适应该海域自然条件的大直径PHC桩施工成为实施本工程施工的关键问题。主要描述在特定的海况环境及地质条件下,东海大桥近岸浅海段桥墩PHC桩的桩型选择及防腐技术、桩靴形式选择及可沉分析、水锤效应及波流影响的对策等关键施工技术。

The bridge axis of Donghai bridge is 31 km and PHC piles are used in the pile foundation of offshore piers.Because this project is far away from the seashore without shield,the construct condition is hostile with strong wind,high wave and rapid flow.Moreover,the geologic structure there is complicated and the salt content of seawater is high,and there is only 174 operational days within a year.Therefore,the key point for the construction of this project is the construction of the large-diameter PHC pile which is adaptable to the natural conditions of such sea area.This paper introduces some key construction techniques applied to PHC piles for offshore piers of Donghai bridge,such as selection of pile type,anti-corrosion technology,selection of pile shoe,settleability analysis,water-hammer response and countermeasures to wave-current effect.