均匀来流中带环翼的复合桩墩的局部冲刷数值试验研究

Numerical Study on Local Scour at Composite Piles with Collars in Uniform Flows

桩墩冲刷是海上风电、跨海大桥安全的最大威胁,如何降低冲刷深度是当下亟待解决的关键问题。安装在桩墩下部的环翼是弱化基础附近水流结构以减少冲刷深度的一种盘状结构。本文利用率定的三维水沙数值模型对带环翼的复合桩墩开展了局部冲刷数值试验,探讨了环翼的位置、厚度、宽度和来流的攻角对局部流场、床面切应力及减冲刷效果的影响。结果表明,环翼的位置、宽度、攻角对局部冲刷影响显著,而其厚度则对局部冲刷效果影响不明显。环翼宽度越大,攻角负值越大,其防冲刷效果越好;当环翼位于承台底边,宽度为1~1.5倍承台高度,环翼攻角为-45°时,其对复合桩墩的冲刷防护效果最好。该结论可为桩基冲刷防护设计提供参考。

Local scour at piles poses a significant threat to the safety of offshore wind power and sea-crossing bridges.Addressing the issue of reducing scour depth is an urgent and pivotal challenge that requires immediate attention.The collar is a disk-like structure that reduces the scour depth by weakening the hydrodynamics around the pile.In this study,numerical experiments on the local scour at composite piles with different collars were conducted.The influence of collar layout position,thickness,width,and attack angle on local flow field,bed shear stress,and scour protection effect were discussed.The results show that the position,width,and attack angle of the collar exert a significant influence on local scour,whereas the thickness of the collar has a negligible impact on its effectiveness in scour protection.The larger the collar width and the negative value of the attack angle,the better the scour protection effect.When the collar is set at the edge of the pile cap foundation,with a width ranging from 1~1.5 times the height of the pile cap foundation and an attack angle of-45°,its scour protection effect on the composite pile is the best.The results can provide references for engineering design of pile foundation scour protection.