涌潮河口桩式丁坝的护滩保塘效果分析

Effect of sheet-pile groins on protecting dykes and flats in tidal bore estuary

针对以散抛块石为材料的传统堆石丁坝基础较浅,处于低潮位上下时散抛块石在涌潮动力作用下往往出现冲散、滚失、沉落,招致丁坝损毁的情况。本文提出了一种桩式丁坝型式,该桩式丁坝除基础深、整体性好外,水上和水下部分的坝头,做成适合流势接近流线的体型,从而可改善邻近丁坝头的流场,减小滩地与近坝头河床的冲刷。本文通过现场观测,分析了桩式丁坝的护滩保塘效果,探究丁坝护滩保塘的机理。分析表明,桩式丁坝可减轻“兜潮”现象,能直接抵御最大涌潮动力的作用,有效地减弱涌潮对坝基的淘刷,削减坝头及丁坝上游侧的局部冲刷强度,较好地解决了丁坝坝身周围局部冲刷坑的问题,大大增强了坝身结构稳定性。与传统的堆石丁坝比较,桩式丁坝具有设计合理、施工简易、便于维护检修等特点,可在各类河道整治、海塘保护等工程中应用。

A new type of groin made up of sheet piles is introduced and its effectiveness of protecting dykes and flats is verified according to field observation data. The groin is built on the very deep foundation and the configuration of the groin is designed to fit the streamline so that the flow field in front of the adjacent groin can be improved resulting alleviation of the erosion of groin foundation and riverbed. The mechanism of the effect on protecting dykes and flats in tidal estuary is analyzed. The optimal design of this type of groin is proposed.