铁路箱梁辐射结构噪声测试与开孔影响分析

Structural Noise Radiation Test and Opening Impact Analysis of Railway Box Girders

基于室内外温差均衡、通风、排水等因素,往往会在铁路简支箱梁顶板、底板、腹板开设数量和尺寸不一的孔洞。现场实测表明,腔内噪声会通过孔洞泄露出去,增大腔外噪声。基于以上原因,有必要研究开孔对箱梁辐射噪声的影响。研究结论表明:箱梁板的振动频率主要集中在40 Hz至250 Hz范围内;底板侧的噪声主要由底板振动而产生;腹板侧的噪声测点主要由腹板和翼缘板的振动产生。比较分析实测值、不开孔模型理论值、开孔模型理论值后发现,开孔模型测点理论值均比不开孔模型理论值大,更接近于实测值。开孔对结构近场噪声影响不可忽略,理论计算时采用开孔计算模型能更好模拟箱梁结构噪声。

Railway simply supported box girder is often perforated on its top plate, bottom plate and web due to the demand of heat balance between the inside and the outside of the box, ventilation, drainage and so on. According to the field measurement, intracavity noise will leak out through the holes and increase the wayside noise. So, it is necessary to study the influence of the perforation on the radiation noise of the box girder. The study shows that the vibration frequency of the box beam plates is mainly concentrated in the range of 40 Hz-250 Hz. The noise around the bottom plate is mainly generated by the vibration of the bottom plate. The noise around the web plate is mainly generated by the vibration of the web and the flange. By comparing the measured and the theoretical values of the models of the box girder with and without perforation,the theoretical value of noise with perforation is larger than that without perforation, and is closer to the measured value. The effect of perforation on the near field noise cannot be ignored. The theoretical calculation model with perforation is able to simulate the structure-borne noise of the actual box girder more accurately.