轨道板声辐射特性

Acoustic Radiation Properties of Railway Slab

板式轨道的噪声辐射比有砟轨道严重。为预测板式轨道的噪声辐射，根据虚功原理或者哈密尔顿原理建立轨道板的振动方程，并通过傅立叶变换得到轨道板在稳态荷载作用下的振动响应，然后用边界元法建立轨道板的声学边界元模型，以轨道板的振动响应作为边界条件计算轨道板的声辐射特性。研究结果表明：轨道板的声辐射效率与频率的关系具有随频率变化的复杂特性，呈非线性，不能用1个简单的解析表达式描述；轨道板的厚度对声辐射效率没有影响，对轨道板的声辐射功率低频段影响较大，高频段影响较小；轨道板面积对轨道板声辐射效率的影响较大，对轨道板声辐射功率的影响甚微；轨道板下橡胶垫板对轨道板的振动和声辐射在50Hz以下及1000Hz以上频段时影响较大，在50～1000Hz频段影响较小；博格轨道板的声辐射效率和声辐射功率在30Hz以下频段时，低于A型轨道板，其他频段均大于A型轨道板。

The slab track has higher noise emissions compared to ballasted track. In order to predict the noise radiations of the slab track, virtual work principle or Hamilton principle has been used to develop the vibration equations of the railway slab. The vibration responses under steady-state load are obtained by Fourier transform. Then an acoustical boundary element model of railway slab whose vibration responses are taken as the boundary conditions is developed to compute the acoustical radiation properties. The results indicate that the relationship between the acoustical radiation efficiency and the acoustical radiation frequency of railway slab has complex characteristics with the variation of frequency and is nonlinear, so the acoustical radiation efficiency of railway slab can not be described with a simple expression. The thickness of railway slab has no influence on the acoustical radiation efficiency, whereas it has relatively great effect on the acoustic radiation power in low frequency than in high frequency. The area of railway slab has relatively greater influence on the acoustic radiation efficiency and little influence on the acoustic radiation power. Rubber pads under the slab have great influence on the vibrations and sound emissions of slab blow 50 Hz and above 1 000 Hz, while have little influence within 5041 000 Hz frequency bands. The acoustic radiation efficiency and acoustic radiation power of Bogl track slab are lower than A-type track slab below 30 Hz, but are greater than A-type track slab in other frequency bands.