基于WFEM和FMBEM的轨道交通长大跨度混凝土箱梁振动声辐射机理研究

随着桥梁建造技术的发展，长大跨度混凝土桥梁在轨道交通中的应用越来越多，列车过桥时引起的振动噪声问题日益突出。然而当前对长大跨度混凝土桥梁振动噪声特性及机理认识不足。现有混凝土桥梁振动噪声预测方法的计算效率随模型自由度的增大而急剧降低，因而不适用于长大跨度混凝土桥梁振动噪声预测。本项目拟基于车-线-桥耦合振动理论、波导有限元法（WFEM）和快速多极子边界元法（FMBEM），提出长大跨度混凝土桥梁振动噪声预测的新方法；在此基础上，以轨道交通中应用较为广泛的长大跨度混凝土箱梁作为研究对象，开展现场测试和数值模拟，研究其振动噪声特性；基于波传播理论，研究箱梁的导波传播特性；结合箱梁振动频谱，探明引起箱梁振动峰值的导波类型；通过声辐射模态，将导波模态与辐射声功率联系起来，研究箱梁的导波传播特性对声辐射特性的影响规律，进而揭示箱梁振动声辐射机理。研究成果对轨道交通减振降噪具有重要的理论意义和实用价值。

With the advancement of bridge construction technology, long-span concrete bridges have been more extensively applied in rail transit. On the other hand, the problem of vibration and noise of long-span concrete bridges induced by passage of trains has become increasingly prominent. However, the vibro-acoustic characteristics and mechanisms of long-span concrete bridges are not yet well understood nowadays. The existing method used for predicting vibration and noise of concrete bridges presents a plummeting computation efficiency with the increase of degrees of freedom (DOFs) of the model, thus it is not applicable to predict vibration and noise of long-span concrete bridges. In this project, a novel method is to be proposed for predicting vibration and noise of long-span concrete bridges based on the train-track-bridge coupling vibration theory, the waveguide finite element method (WFEM) and the fast multipole boundary element method (FMBEM). On this basis, the vibration and noise characteristics of a long-span concrete box-girder bridge, which is widely used in rail transit, will be studied through performing field tests and numerical simulations. The wave transmission characteristics of the box-girder bridge will be investigated based on the wave propagation theory. Combining with the vibration spectra of the box-girder bridge, the wave modes that causes the vibration peaks of the box-girder bridge will be identified. The relationship between the wave modes and the radiated sound power will be established through the acoustic radiation modes, which will then be used to explore the influence laws of the wave transmission characteristics on the acoustic radiation characteristics of the box-girder bridge. Finally, the vibro-acoustic mechanisms of the box-girder bridge will be revealed. The research achievements will have important theoretical significance and practical value for vibration and noise reduction of rail transit.