高速铁路半封闭式声屏障降噪效果测试与分析

当前半封闭式声屏障逐渐在高速铁路工程中得到了应用，但其在运营状态下的实际降噪效果研究还极其有限.为此，以沪昆客专杭长段半封闭式声屏障为工程背景，分别在声屏障内、外表面，以及封闭侧和敞开侧不同距离处布置测点，监测高速列车通过时的噪声，并对场点的声压级频谱、声场分布、衰减规律、隔声量和插入损失等声学特性进行讨论.结果表明:多重反射造成的混响效应使得半封闭式声屏障内表面的噪声有所增大；距封闭侧线路中心7.5 m处，高位测点比低位测点声压级大，而其他位置不同高度测点在垂向的指向性不明显.半封闭式声屏障的隔声量随频率增加而增大，在1 000 Hz处最大约26 dB；距轨道中心线7.5 m和25 m处的插入损失均值为16.5 dB（A）和15.5 dB（A）. 

Field Test and Analysis of Noise Reduction Performance of High-Speed Railway Semi-Closed Sound Barriers

Semi-closed sound barriers are increasingly used in high-speed railway engineering, however, research on its noise reduction effect in operation is extremely limited. Based on the Shanghai to Kunming passenger line, noise measurement points were respectively arranged on the inner and outer surface of the semi-closed sound barrier, and the opened and closed sides, at different distances. Noise signals during high-speed train passing-by were monitored. Acoustic characteristics in terms of sound pressure level spectrum, sound field distribution, attenuation law, sound insulation and insertion loss were discussed. Results indicate that the reverberation effect caused by multiple reflections increases the noise on the inner surface of the semi-closed sound barrier; at a distance of 7.5 m from the track centerline, the sound pressure level of the higher measuring point is larger than that of the lower measuring point, and the directivity of the noise distribution is not evident for other measuring points at different heights. The sound insulation of the semi-closed sound barrier increases with the increase in frequency and reaches a peak of 26 dB at 1000 Hz; the insertion loss at a distance of 7.5 m and 25 m from the track centerline is 16.5 dB(A) and 15.5 dB(A), respectively.