Research On Noise Reduction Effect Of High-speed Railway Sound Barrier Based On Sound Field Distribution Characteristics

Mass construction and operation of high-speed railway provides strong support for China's social and economic development and greatly improvides the convenience of people's travel.However,the noise generated by high-speed railway has a great impact on the residents in some areas along the route.In order to reduce the influence of high-speed railway noise,sound barriers are often installed on both sides of railway lines.Sound barrier technology is the most widely used and operable noise control measure.The railway maintenance,safety limits and other restrictions,high-speed railway noise barrier in China is given priority to with upright,but there are many factors that affect the noise reduction effect of the sound barrier.The distribution characteristics of sound source,the sound barrier material and sound absorption and sound insulation performance,the height of the sound barrier,and the top structure form of the sound barrier all have a great impact on the noise reduction effect of the sound barrier.So based on the in-depth analysis of the high-speed railway noise barrier application status at home and abroad,the noise reduction effect and existing problems,on the basis of based on alignment joint-test of high-speed rail,the research of high speed railway noise sound field characteristics and acoustic barrier spatial distribution features,systematically analysis noise barrier height,acoustic barrier material,acoustic barrier structure,the structure vibration noise barrier and the secondary noise,speed of EMU on noise reduction effect of high-speed railway.The main process and conclusions of this paper are given below:First of all,the application status and research results of sound barrier in home and abroad were collected,the key influencing factors such as sound barrier material,height and structure which have an impact on noise reduction effect were organized: on the surface of rail at a distance of 25 m to central line of the track,the noise reduction effect of sound barrier decreased with the increase in speed of EMU,the noise reduction of sound barrier decreased 2-3dB(A)for every speed up of 100 km.In the case that EMU passed through the sound barrier in the bridge at the speed of 200km/h and 260km/h,the noise reduced by sound barrier decreased 2~4dB(A)for every increase of 1m in the height of sound barrier.Metal noise barrier has better noise reduction effect than non-metal noise barrier.Through the analysis on spectrum of sound barrier,it was found that low-frequency range lower than 200 Hz has a low noise reduction while medium-high frequency range higher than 640 Hz has a higher noise reduction.Then,the sound field distribution characteristics of the bridge section and the sound barrier section when the high-speed train of Beijing-Shanghai line passes at 300km/h are analyzed.Analysis indicates that the high-speed railway noise pointing to the characteristic of acoustic field distribution is obvious,the sound barrier has a poor noise reduction effect on sound sources at high positions such as pantograph,and a good noise reduction effect on wheel-rail area and some vehicle body areas.Therefore,the sound source distribution and sound field distribution characteristics of the EMU must be considered in the calculation of sound barrier noise reduction effect of highspeed railway sound barrier.Finally,based on the quantitative analysis results of noise sources outside highspeed railway vehicles,the noise sources are divided into three equivalent sound sources according to the characteristics of different sound sources.Virtual.Lab acoustic simulation software and sound line tracking method are combined to establish the simulation calculation model of noise reduction effect of sound barrier of high-speed railway,and verify the model calculation results and field test results.The research shows that the deviation between the calculated value and the measured value of the non-sound barrier section at a distance of 25 m from the central line was within 1dB(A),and the maximum calculated deviation after setting the sound barrier was 0.1dB(A).It is fully demonstrated that the simulation analysis model of noise reduction effect constructed in this paper can meet the application analysis requirements of sound barrier engineering in China's high-speed railway.The simulation and calculation model of the sound barrier established in this paper is used to analyze the noise reduction effect of different heights of the sound barrier and the top structure.The analysis results show that:(1)As the height of sound barrier increases,the sound attenuation and height of each measurement point increased logarithmically.(2)The 2m-3m vertical sound barrier has better noise reduction effect and practicability.(3)When the height of the sound barrier is limited,the vertical inverted L-type or T-shaped structure can be used instead of the vertical type in the 3m high sound barrier,and the noise reduction is 1.7~3.2dB(A)higher than the vertical sound barrier with same height.But the additional noise reduction effect of the top structure is mainly in the near field,and the additional noise reduction effect is small beyond 60 m from the railway center.