高速铁路全封闭声屏障降噪特性足尺模型试验研究

A Full-scale Model Test of Noise Reduction Performance of Fully-enclosed Noise Barriers on High-speed Railway

全封闭声屏障可有效降低噪声,其降噪特性对于高速铁路全封闭声屏障设计具有重要意义。基于足尺模型试验,采用扬声器在其内部播放粉红噪声和实测高速列车噪声模拟声源,分别在自由场地、金属声屏障、混凝土声屏障3个断面进行测试。对两种声屏障内部声场混响效应的差异进行对比,并通过降噪量和插入损失对声屏障降噪特性进行讨论。试验结果表明:提出的针对全封闭声屏障的声学试验方案可行,包含在模型边界处理、声源模拟以及测点布置等多方面内容;两种声屏障均对中高频噪声具有较好的隔声性能,金属声屏障在中高频段降噪量优于混凝土声屏障,混凝土声屏障在低频段降噪量优于金属声屏障;全封闭声屏障存在“混响效应”,金属声屏障内部声场增大3~4 dB(A),混凝土声屏障内部声场增大6~7 dB(A);在封闭良好的试验条件下,距轨道中心线7.5 m处,金属和混凝土声屏障的插入损失分别为25 dB(A)和22 dB(A)。

As fully-enclosed noise barriers can effectively reduce noise,their noise reduction performance plays an important role in the design of fully-enclosed noise barriers on high-speed railway.Based on the full-scale model test,the noise sources were simulated by microphones to play pink noise and measured train noise,and the sound pressure levels(SPLs)of field points on three test sections were tested respectively,including free field,metal noise barrier,and concrete noise barrier.The reverberation effects of internal sound field in fully-enclosed noise barriers were analyzed.The noise reduction characteristics of the barriers were studied by noise reduction and insertion loss.The results show the feasibility of the scheme of full-scale model test,including model boundary treatment,sound source simulation and measurement point layout.Both kinds of the noise barriers have good sound insulation performance against medium and high frequency noise.The noise reduction of the metal noise barrier is better than that of the concrete noise barrier in medium and high frequency band,and the concrete noise barrier is better than the metal noise barrier in noise reduction in low frequency band.There is“reverberation effect”in fully-enclosed noise barriers,with the sound field inside the metal noise barrier increasing by 3~4 dB(A),and that inside the concrete noise barrier increasing by 6~7 dB(A).At 7.5 m from the track center line,the insertion losses of the metal noise barrier and the concrete noise barrier are respectively 25 dB(A)and 22 dB(A)under well-confined test conditions.