考虑波致地基动力响应的跨海桥梁高桩承台局部冲刷机理研究

跨海桥梁工程是我国建设海洋强国和交通强国的重要支撑，局部冲刷是跨海桥梁设计与建造必须考虑的关键问题，而跨海桥梁高桩承台局部冲刷机理仍未透彻。本项目将采用透明土水槽试验与数值模拟相结合的手段，对考虑波致地基动力响应的跨海桥梁高桩承台局部冲刷机理开展研究。首先，基于透明土水槽试验，分析波流耦合下高桩承台的地基动力响应和局部冲刷特性，厘清地基动力响应与局部冲刷的主控参量。然后，耦合分析地基超静孔隙水压力响应与冲刷坑空间尺度演化和表层土颗粒起动过程，揭示高桩承台地基动力响应与局部冲刷之间的耦合机制。最后，量化地基动力响应与局部冲刷的相互影响，建立体现地基动力响应的局部冲刷模型，凝练高桩承台局部冲刷的关键影响因素，从而提出一套考虑波致地基动力响应的跨海桥梁高桩承台极限平衡冲刷深度预测方法。研究成果既可加深对高桩承台局部冲刷流-固-土耦合机制的认识，亦可为跨海桥梁冲刷稳定性评价提供科学依据和有效工具。

The development of sea-crossing bridge engineering is an important support for China's construction of both the maritime power and the transportation power. Local scour is a key issue that must be considered in the design and construction of sea-crossing bridge. However, the local scour mechanism of elevated pile cap for sea-crossing bridge is still unclear. In this project, transparent soil flume test and numerical simulation are combined to study the local scour mechanism of elevated pile cap for sea-crossing bridge considering wave-induced seabed response. Firstly, based on the transparent soil flume test, the dynamic response and local scour process around the elevated pile cap under wave-current loads are analyzed, and the typical characteristics of the seabed dynamic response and local scour are clarified. Then, the coupling mechanism between the response of excess pore water pressure within the seabed and the spatial scale evolution of scour pits as well as the initiation process of surface particles is analyzed. Finally, the interaction between seabed dynamic response and local scour is quantified, the local scour model reflecting seabed dynamic response is established, and the key influencing factors of local scour of elevated pile cap are summarized, thus a set of prediction method for ultimate equilibrium scour depth of elevated pile cap for sea-crossing bridge considering wave-induced seabed response is proposed. The research results can not only deepen the understanding of fluid-solid-soil coupling mechanism of local scour of elevated pile cap, but also provide scientific basis and effective tool for scour stability evaluation of sea-crossing bridge.