| High-speed railway is a major breakthrough in the construction of an innovation-oriented country in China and a landmark achievement of independent innovation.While improving the comfort and convenience of passenger travel,the impact of high-speed railway on environmental noise along the line has become a problem of wide public concern and a major factor restricting its further development.As the main protection measure to reduce the sound propagation from the sound source to the sound point,sound barrier is the most widely used noise control measure along the high-speed railway in China at present.With a large number of high-speed rail lines put into operation,high-speed railway has gradually stepped into operation stage from large-scale infrastructure construction stage.Some major high-speed railway lines in China have been put into operation for 10 years.With the increase of operating time and acoustic barrier use fixed number of year,especially in the high-speed train long alternating aerodynamic load,material change,and natural factors,the performance of sound barrier in service may change to some extent,which will affect its use effect,the acoustics performance,noise reduction effects may also change with the increase of operating time.However,there is less concern about the performance of sound barrier in operation in China and abroad.Therefore,studying the aerodynamic effect and noise reduction performance of high-speed railway sound barriers after long-term operation and analyzing the performance evolution law of sound barriers during service period can not only evaluate the current use effect of sound barriers,but also have great significance for guiding the optimization design and safety assessment of high-speed railway in China.In this paper,the metal sound barrier of a high-speed railway bridge is selected as the research object.Combined with field tests and simulation analysis,the service performance of the sound barrier is systematically studied and compared in the initial period of operation and 10 years after operation,so as to master the changing trend of the dynamic performance and noise reduction performance of the sound barrier during the service period of high-speed railway in China,and analyze the main reasons.The main research work are as follows:(ⅰ)The research status of sound barrier at home and abroad and the theoretical analysis and calculation methods are investigated and analyzed.Based on this,the research method and field test scheme of this paper are formulated.(ⅱ)Based on field tests in operation period,the effects of different vehicle speeds,vehicle types and test stages on aerodynamic effects of sound barriers after 10 years of operation are summarized.Compared with the initial stage of operation,the aerodynamic pressure load of the sound barrier is basically the same,while the maximum displacement of the unit plate and the column increases by 38.3% and 10.8%,respectively,and the maximum stress of the column decreases by 45%.According to the analysis,the main reason for the above changes is that the bearing capacity of the bearing parts,restraints and connecting parts of the sound barrier has decreased to a certain extent under the condition of long-term operation.(ⅲ)Based on field tests in operation period,the effects of different vehicle speeds,vehicle types and test stages on noise reduction effect of sound barrier after 10 years of operation are summarized and analyzed.Compared with the initial stage of operation,the analysis results show that the noise reduction effect of the sound barrier has been reduced to some extent,and the reduction value is mostly between 1 and 2d B(A).In combination with the simulation analysis of LMS Virtual.Lab,it can be seen that the decrease of sound absorption coefficient of sound barrier caused by cracking of sound absorbing rock wool will reduce the noise reduction effect of sound barrier. |
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