The Research On The Design And Performance Of The Urban Low-height Trackside Soundproof Wall

At present,China’s urban rail transit construction has a rapid development,but it also brings the corresponding traffic noise problems to the city.China mainly uses noise barriers installed along the track to deal with urban rail traffic noise.However,traditional acoustic barriers are large in size and high in height,also have many shortcomings.For that,foreign researchers have designed and invented a low-height trackside soundproof wall to replace noise barriers to solve urban rail traffic noise problems.Currently,the research and design standards for the low-height trackside soundproof walls are still in the hands of other countries,and China has not yet conducted research and application of this product.The article analyzes a large number of related literature,analyzes the main components and frequency characteristics of China’s urban traffic noise.On this basis,based on China’s current rail traffic regulations as a design basis,the design of the low-height trackside soundproof wall was carried out,and the results were checked for stability and noise reduction.Using the acoustic module of Virtual.Lab software,corresponding acoustic simulation calculations were performed.The paper mainly includes the following:1.The acoustic theory related to low-height trackside soundproof walls was introduced and analyzed,mainly including: basic acoustic quantity,noise composition and frequency characteristics of rail transit in China,the basic theory of noise reduction on low-height trackside soundproof walls,and the noise attenuation model of that kinds of walls.Among them,China’s rail traffic noise is mainly wheel-rail noise,and the peak frequency is mainly in the frequency band of 500-800 Hz.It is practically feasible to use the low-height trackside soundproof wall to control noise at the near-track.2.With reference to foreign design experience,the low-height trackside soundproof wall was designed.According to the design standards of the widest vehicle A-type in China’s urban rail transit,according to the relevant standards on the boundaries of the provisions,as well as the law of quality of sound insulation,the calculation method of the position design,height design,and the minimum acoustic thickness were deduced in turn.Then designed a kind of low-height trackside soundproof wall.This design adopts a composite form.The design of the low-height trackside soundproof wall surface is 150 mm thick ceramsite concrete sound-absorbing layer,and the back is 50 mm thick self-developed high performance concrete sound-insulation layer.The horizontal wind load and the aerodynamic load of the urban rail transit in China were deduced,and the overturning stability of the designed low-height trackside soundproof wall was checked.The results show that the stability factor for overturning under different working conditions is greater than 1.5,which meets the stability requirements.Using the prediction formula of the noise reduction amount listed in Chapter 2,the design of the low-height trackside soundproof wall is checked.The noise reduction in the 500～800Hz frequency band is greater than 10 d B(A),which means the acoustic performance is good.3.Using the Virtual.Lab simulation platform,the sound insulation of the designed low-height trackside soundproof wall was calculated using acoustical direct coupling finite element method.The results showed that: in the range of 100～3150Hz,1/3 octave center frequency,the weighted sound insulation of the designed low-height trackside soundproof wall is 27.35 d B(A).In the noise peak frequency range from 500 to 800 Hz,the sound insulation is greater than 22 d B(A),which meets the design requirements.4.Using the Virtual.Lab simulation platform,acoustical indirect boundary element method was used to calculate the noise reduction ability of low-height trackside soundproof walls with different top-forms at different sound receiving points.The result shows,the low-height trackside soundproof walls on the track side have better protection effects on the receiving areas of lower areas,such as pedestrians;The low-height trackside soundproof walls with different top structures have differences in noise reduction peak,peak frequency and frequency characteristics,which means it is feasible to select a optimization according to the actual situation.