复杂海域跨海桥梁围堰随机波浪力作用机理及计算方法研究

The proposal aims at the key issues in the construction of sea-crossing bridge foundations in complicated sea conditions, which need to be resolved urgently. The mechanics of interaction between random wave and bridge cofferdam with typical cross section and the calculation method of randonm wave loads will be studied. The investigation will be conducted by the combination of numerical simulations and wave flume tests. The realistic sea wave environment of Ping-tan strait railway-highway bridge will be chosen as a sample area. In this proposal, reasonable wave spectrum form for the sample area will be firstly established according to the on-site measured datas of wave elevation by means of theoretical analysis. Secondly, three-dimensional mathematical model will be established to simulate the interaction between random wave and bridge cofferdam with typical cross section. The reliabilty of the mathematical model will be verified by the wave flume tests of bridge cofferdam. Afterwards, the mathematical model will be applied to investigate the mechanics of interaction between random wave and the bridge cofferdam. The detailed flow pattern such as wave runup, wave pressure distribution will be studied, from which the exact mechanics of random wave force acting on bridge cofferdam can be figured out physically. With the mechanics clarified, calculation method of random wave forces for typical sea-crossing bridge cofferdam will be established. This proposal will give a theoretical foundation and technical support for the design and coonstruction of sea-crossing bridge cofferdam in complicated sea conditions.

本项目针对复杂海域跨海桥梁基础建设中亟待解决的关键问题，采用三维数值仿真和波浪水槽模型试验相结合的方法，开展跨海桥梁围堰随机波浪力作用机理及计算方法的研究。拟以在建的平潭海峡公铁两用大桥所在海域为研究区域，首先根据现场实测波面资料和理论分析，建立适合该海域的波浪谱。在此基础上，建立随机波浪与典型跨海桥梁围堰相互作用的三维数学模型。该数学模型的有效性由波浪水槽模型试验验证，用于随机波浪与典型跨海桥梁围堰相互作用机理的研究。该研究深入分析围堰周围的波面爬高、波压力分布等流场分布特征，从物理层面上揭示围堰随机波浪力作用机理，建立典型跨海桥梁围堰随机波浪力的计算方法，为复杂海域跨海桥梁围堰的设计与施工提供基础理论依据和技术支撑。

本项目针对复杂海域跨海桥梁基础建设中亟待解决的关键问题，采用数值仿真、波浪水槽试验和理论分析相结合的方法，开展了跨海桥梁围堰随机波浪力作用机理及计算方法研究。首先，基于理论分析对平潭海峡公铁两用大桥桥址区的波浪谱进行研究。由JONSWAP谱峰因子及新增参数的联合修正，获得与实测谱吻合较好的拟合谱。其次，由于随机波浪可看作无限多个振幅、频率不等、初相位随机的规则线性波叠加而成，课题开展了不同频率成分的规则线性波与典型跨海桥梁围堰相互作用的数值模拟与水槽试验研究。基于垂向坐标变换法和浸没边界法建立三维波浪与结构相互作用的数学模型，对典型围堰规则波浪力作用进行数值仿真，结合波浪水槽模型试验从物理层面上揭示了结构规则波浪力作用机理。聚焦波可视为一种特殊的随机波，研究中还开展了聚焦波与典型跨海桥梁围堰相互作用的水槽试验，分析了入射角、吃水深度、波幅等参数对结构受力的影响，提出了典型围堰聚焦波浪力谱的简化算法。最后，基于数值模拟和波浪水槽试验深入分析了典型跨海桥梁围堰随机波浪力特性，充分考虑了入射角、吃水深度、有效波高和有效波周期的影响，并和规则波浪力进行对比，从时域和频域角度对围堰随机波浪力特性进行深入详细分析。由于实际海洋环境中伴随着波流共同作用，在上述研究基础上课题还开展了典型跨海桥梁围堰波流力作用的数值模拟与水槽试验研究，研究结论可为实际跨海桥梁基础工程抵抗波浪（流）力设计与施工提供科学理论支撑。