权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

A study on the excess attenuation of the noise barrier with acoustically soft and unique shape edge

声学柔和且形状独特的边缘声屏障的超量衰减研究

基本信息

批准号：
10450213
负责人：
FUJIWARA Kyoji
金额：
$ 3.26万
依托单位：
Kyushu Institute of Design
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-10450213/
关键词：
road traffic noise noise barrier 土木音響学道路交通騒音

项目摘要

The aim of this paper is to develop a noise barrier, which gives large excess attenuation despite its low height. For realizing the barrier two different mechanisms were employed. One is T shape in barrier cross-section and the other an acoustic soft surface.The acoustic soft surface is obtained by arranging 1/4 wave length acoustic tubes over the barrier surface, but the sound pressure level at the tube mouth becomes quite large at the frequency a little lower than the design frequency. To reduce this pressure increase the fibrous material was attached at the mouth. Although this material reduced the pressure increase, the pressure release at the design frequency was also rose a little and then the excess attenuation by the barrier reduced for wide band noise.Another method to reduce the pressure increase was examined. This method was to cancel the pressure increase of the acoustic tube of certain depth by the pressure release of another acoustic tube of different depth. Therefore many acoustic tubes of different depths were arranged over the top area of T shape barrier of 2m widths. The shortest tube is 12cm and the longest 60cm. The numerically obtained excess attenuation by this barrier was quite large.Then the performance of this barrier for road traffic noise was compared with that of really existing huge noise barrier of 9m in height, 6.3m bended portion to roadside and 14m in total cross-section. In the case of our soft T shape barrier the barrier needs only 6m in height and 2m in width to get the same excess attenuation as that of the huge barrier. This fact was verified by both of the numerical calculation and experimental study.As mentioned above, the aim of this study was almost satisfied, and a new barrier system of T shape and acoustic soft surface was obtained. Unfinished work is to derive a simple prediction method of the excess attenuation of the barrier in the case when it is constructed along the real road.

本文的目的是开发一种声屏障，它提供了大的额外衰减，尽管它的高度低。为了实现屏障，采用了两种不同的机制。一种是声屏障横截面为T形，另一种是声学软表面，声学软表面是在声屏障表面上布置1/4波长的声管而得到的，但在略低于设计频率的频率处，管口处的声压级很大。为了减少这种压力增加，纤维材料附着在嘴部。虽然这种材料降低了压力的增加，但在设计频率下的压力释放也略有增加，从而减少了屏障对宽带噪声的过度衰减。这种方法是通过不同深度的另一根声管的压力释放来抵消一定深度的声管的压力增加。为此，在2 m宽的T形声屏障顶部区域布置了多根不同深度的声管。最短的管子是12厘米，最长的是60厘米。数值计算结果表明，该声屏障对道路交通噪声有较大的过量衰减，并与实际存在的高9 m、向路边弯曲部分6.3m、总截面14 m的巨型声屏障进行了比较。在我们的软T形屏障的情况下，屏障仅需要6 m的高度和2 m的宽度，以获得与巨大屏障相同的过量衰减。数值计算和实验研究都证实了这一点，基本上达到了本研究的目的，得到了一种新型的T形声屏障系统。未完成的工作是推导出一个简单的预测方法的情况下，当它是沿着真实的道路建造的障碍物的过度衰减。