Application Of Three-Source Model In Hihg-Speed Railway Noise Prediction

High-speed railways are an important part of China’s modern transport system.By the end of 2021,the mileage of high-speed railways operating in China exceeds40,000 km.Railway noise pollution has become the focus of social attention.The noise sources of high-speed railways can be divided into three major parts: wheel track noise,car body aerodynamic noise and collector system noise.As the speed of high-speed trains continues to rise,the contribution of each part of the noise source varies.The proportion of body aerodynamic noise and collector system noise increases.This paper adopts the three-source model used in the Technical Guidelines for Environmental Impact Assessment Sound Environment(HJ2.4-2021)promulgated in March 2022 and the single-source model used in the Guidance on the Source Intensity of Noise and Vibration for Environmental Impact Assessment of Railway Construction Projects and Principles of Management(Railway Planning [2010] No.44)for environmental noise prediction of high-speed railways.Study.The 3.3m high sound barrier was predicted using the single source model,the dual source model and the triple source model for insertion loss prediction.A three-source simulation model was developed using Cadna/A software.The following conclusions were reached:1.The single source and three source modes were used to predict the noise during the horizontal passage of a single train at different speeds.It was concluded that the difference in noise prediction values between the two prediction modes decreases as the operating speed increases along the horizontal direction for the same track form.The noise prediction values for ballastless track are higher than those for ballasted track at the same speed.The predicted noise values for the roadbed section are higher than those for the bridge section.For the same speed and track type,the noise prediction of the single source mode decays faster along the horizontal direction.2.Using the Chengdu-Chongqing Central Railway as a background,two prediction models were used to analyse the noise prediction of high-level acoustic environmental protection targets.It is concluded that the overall trend is to increase and then decrease as the height of the floor changes.The single-source model accelerates the decay rate of the predicted noise values when the angle between the source and the sound-receiving point and the horizontal plane is between 24° and 50°.3.The low and middle floors of the roadbed and bridge sections do not meet the requirements of the daytime and nighttime limits of the corresponding sound environment functional areas,and the noise pollution is serious.4.A standing 3.3m sound barrier was installed at the sound protection target of the bridge section.The insertion loss of the sound barrier was predicted using the single-source,dual-source and three-source models.The average insertion loss was8.2 d B(A)for daytime and nighttime in the single source mode,7.2 d B(A)in the dual source mode and 4.1 d B(A)in the triple source mode.5.Based on the Chengdu-Chongqing Central Line as the background,Cadna/A software was used to establish a three-source model for the simulation of acoustic environmental protection targets.The environmental noise prediction was carried out for the sound environmental protection target.Conclusion: Cadna/A software simulation results of three sound sources prediction results fit well.The average difference between the two is 0.76 d B(A)during the daytime and 0.52 d B(A)at night for the bridge section,0.96 d B(A)during the daytime and 0.86 d B(A)at night,For the sound barrier insertion loss prediction,the average insertion loss was 5.1 d B(A)during the daytime and 4.3 d B(A)at night for the sound barrier,which is 1 d B(A)different from the predicted insertion loss of the three-source model.Cadna/A software can be used to establish a three-source model for environmental noise prediction and sound barrier insertion loss prediction for the sound protection targets.