高速铁路32m简支箱梁声辐射特性研究

Sound Radiation Characteristics of 32 m Simply Supported Concrete Box Girder Applied in High-speed Railway

将列车-轨道-桥梁耦合振动理论与声辐射分析边界元法相结合,分析高速铁路32m单箱单室和单箱双室箱梁声辐射特性。结果表明:单箱单室箱梁动力响应均大于单箱双室箱梁,2种截面梁型在10～100Hz范围内振动密集,表现出结构局部振动特性,须采用板单元进行动力分析;箱梁结构噪声以低频为主,分布在小于250Hz频带内,适合采用边界元法求解;各场点声压级在梁底空间变化较小,距离每增加2m,声压级平均降低1.2dB,越靠近地面,声压级衰减越小;各场点声压级随与桥梁中心线距离的增大而减小,距离每增加9m,声压级平均降低3.7dB;距桥梁中心线25m处,各场点声压级随距地面高度增加而减小;行车速度为160～240km/h时,单箱单室箱梁比单箱双室箱梁声压级平均大14.2～4.3dB,速度越高,声压级差别越小。

The train-track-bridge coupling vibration theory and boundary element method（BEM） were applied to establish a numerical model for calculating noises radiated by bridge. Two types of simply supported concrete box girders, single box with single room and single box with two rooms, with a span of 32 meters, were simu- lated for case study. The calculation results indicate as follows= The dynamic responses of the single box with single room are larger than the single box with two rooms, vibrations of the two types of box girders are dense in the range of 10-100 Hz, showing the local vibration characteristics, and the plate element model is more suitable for bridge dynamic analysis; the bridge structure noises mainly distribute in the frequency band lower than 250 Hz and are appropriate to be calculate with the BEM; the sound pressure levels （SPL） of field points change within a small range in the space below the bottom plate of the girder, the SPL descends by 1.2 dB av- eragely for each additional distance of 2 m, and the closer the point to the ground, the smaller the SPL attenua- tion; the SPLs of field points decrease with increase of the distance perpendicular to the bridge centre line by an average value of 3.7 dB for each additional distance of 9 m; at the position of 25 m away from the bridge center line, the SPLs of field points decreases gradually with increase of the distance to the ground; when the train speed varies from 160 to 240 kin/h, the SPL of the single box with single room is larger than the SPL of the single box with two rooms by an average value of 14.2-4.3 dB, and the higher the train speed, the smaller the SPL difference.