桥梁截面形式对轨道交通高架噪声的影响

城市轨道交通高架一般采用预应力混凝土简支梁，其截面形式不但直接影响桥梁振动及其结构声辐射，还间接影响轮轨噪声的传播. 为给低噪声轨道交通的高架桥梁截面选型提供依据，本文采用功率流方法计算轮轨滚动激励引起的轨、桥空间平均振动均方速度，结合声有限元-无限元方法分析钢轨噪声和桥梁结构噪声的产生与传播，对比研究了某U型梁、单箱单室梁及双箱双室梁的振动及其声辐射的差异. 结果表明:桥梁截面形式对钢轨振动影响很小，但明显影响钢轨噪声辐射；截面形式对桥梁振动及结构噪声的影响均很大. 就钢轨噪声而言，U型梁相比箱形梁小1～3 dB(A)；但在桥梁结构噪声方面，单箱单室梁较U型梁小2～10 dB(A)，双箱双室梁较单箱单室梁可再减小2～6 dB(A). 

Influence of Section Types on Noise from Elevated Rail Transit Lines

Simply-supported pre-stressed concrete bridges are widely adopted in urban elevated rail transit systems. The section types of the bridges not only affect bridge vibration and structural acoustic radiation, but also have an indirect influence on the propagation of wheel-rail noise. Thus, this work aims to provide guidelines on the selection of section types of bridges for low noise produced by elevated rail transit systems. The power flow method was first applied to obtain the spatially averaged vibration velocities of the rail and bridge considering wheel-rail interaction. The coupled finite-infinite element method was then used to analyze the generation and propagation of rail noise and bridge structural noise. The vibrations and noise radiation of the bridges of U-shaped girder, single-box single-cell box girder, and twin-box twin-cell box girder were compared. The results reveal that although the section types have a small effect on the vibration of the rails, they have large influence on rail noise radiation. Furthermore, both the vibration and structural noise of the bridges are significantly affected by the section types. In terms of rail noise, the U-shaped girder leads to 1-3 dB(A) lower rail noise level than the box girder. However, with respect to the bridge structure noise, the single-box single-cell box girder generates noise 2-10 dB(A) lower than the U-shaped girder, and the twin-box twin-cell box girder generates noise 2-6 dB(A) lower than the single-box single-cell box girder.