高速铁路箱梁桥-声屏障结构振动噪声初探

Preliminary Study on Structure-borne Noise of Box Girder Bridge-sound Barrier in High Speed Railway

声屏障是轨道交通重要的降噪措施之一,但在列车经过时声屏障同样会产生振动成为向外辐射噪声的声源.以内折型声屏障为研究对象,将其简化为适用于声学计算的板壳单元,通过建立高架线路结构的有限元模型,以中国高速铁路无砟轨道谱作用下的声屏障以及箱梁桥-声屏障的动力学响应作为声学边界条件,基于有限元-边界元理论分别求解单独声屏障和箱梁桥-声屏障的声辐射特性,初步探究了声屏障对高架路段结构声辐射的影响,在此基础上进一步考虑了地面反射的作用.研究结果表明:声屏障的振动形式主要表现为水平局部振动以及垂向整体振动,水平局部振动对自身结构噪声辐射的影响最大,其结构噪声集中在0~180 Hz的低频段,与桥梁结构噪声频率范围重合度较高;桥梁上安装声屏障后的振动分布发生明显地改变,使得声压在部分频段内降低,周围声场的分布也发生了明显变化而且总体上声压增加了1~2 dB;刚性地面的反射会使整个声场的声压增大,声压增加值最大可达5 dB.因此,声屏障对高架线路的整体结构声辐射能够产生很大的影响,考虑地面反射的作用后更加显著.

The sound barrier is one of the important reduction noise measures in rail transit,but the sound barrier on bridge will produce vibration when the train passes and become a sound source of radiate noise as well.In this paper,the interior folding sound barrier is taken as the research object and it is simplified to the shell element for acoustic calculation.The finite element model structure of elevated line is established.The acoustic barrier under the action of ballastless track spectrum of China high-speed railway and the dynamic response of box girder bridge-acoustic barrier is used as the acoustic boundary condition.Based on the finite-boundary element theory,the acoustic radiation characteristics of single sound barrier and box girder bridge-sound barrier are solved respectively.The influence of sound barrier on the elevated structure acoustic radiation is preliminary studied,on this basis,the effect of ground reflection is considered in further.The results show that the vibrations of the sound barrier are mainly local vibration of horizontal direction and global vibration of vertical direction,and the local vibration of horizontal direction has obvious effects on its structure noise.The structure noise of the sound barrier mainly concentrates in a low-frequency band of 0-180 Hz which has a higher coincidence in the frequency range of the noise radiated by the box girder;after the installation of sound barriers,the vibration distribution of the bridge will change,and the global structure noise will decrease in some frequency ranges while the distribution of sound field around the bridge is changed and the sound pressure is increased by 1~2 dB.Affected by the reflection of the rigid ground,the sound pressure of any point in the sound field will increase,and the maximal increase value is up to 5 dB.Therefore,the sound barrier has great influence on the structure acoustic radiation of the elevated line,and it is even greater when the ground reflection is taken into consideration.