轨道交通混凝土U梁减振降噪措施数值分析

Numerical study on vibration and noise reduction of rail transit concrete U-shaped bridges

为了研究减振降噪措施对轨道交通U梁的振动噪声影响,利用车辆轨道桥梁耦合振动模型和声学有限元/无限元方法,分析了采用3种降噪措施(设置声屏障、采用高弹性扣件和铺设梯形轨枕)后轨道交通U梁、轨枕和钢轨的噪声.研究结果表明,声屏障能有效降低离U梁轨道中心线5 m以外场点的钢轨噪声,但是对桥梁结构噪声影响很小;低刚度扣件能有效降低桥梁的振动和结构噪声,而钢轨振动和辐射噪声则略微增加;梯形轨枕能显著降低传入桥梁的振动能量,进而大幅度降低桥梁结构噪声,但是梯形轨枕自身的振动较大,可能会成为主要的噪声源之一,梯形轨枕对钢轨辐射噪声则影响很小.在进行减振降噪分析时,需根据噪声源的贡献大小选择合理的降噪措施.

To study the influence of noise mitigation measures on rail transit bridges, the vehicle-track-bridge interaction analysis model and the infinite element acoustic model were used to predict the sound pressure radiated from the concrete U-shaped bridge, rail and sleeper by three countermeasures, including the installation of noise barrier, the use of low stiffness rail fastener and the installation of ladder track. The research results show that the noise barrier can effectively reduce the noise radiation from rail at field points 5 m away from the track centre, while the effect on bridge noise is insignificant. The rail fastener with low stiffness can effectively reduce the bridge vibration and the associated noise radiation, while the rail vibration and the corresponding noise radiation are slightly improved. The vibration and noise radiation of the bridge can be significantly mitigated by using ladder tracks. However, the excessive vibration of the ladder track induces high noise level, which may become a major noise source. The influence of the ladder track on rail noise is negligible. Appropriate noise mitigation measure should be used in accordance with the major noise source.