Analysis of Sonic Boom Phenomenon and Mitigation Measures in Long Tunnels of High Speed Railway
In view of the sonic boom phenomenon in high speed railway tunnels,this paper sorts out typical cases of sonic boom in high speed railway tunnels at home and abroad by means of literature research.Based on the conducted real vehicle test and simulation research,this paper analyzes the causes of sonic boom phenomenon,basic characteristics of noise,as well as different mitigation measures and effects.The results indicate that:Sonic boom phenomenon mainly occurs in long tunnels with a length greater than 5 km and using ballastless tracks.Under the influence of factors such as tunnel clearance area and portal buffer structure type,the critical train speed for sonic boom in different tunnels is different.The compression wave in the long tunnel is excited during its propagation,resulting in steep deformation of the compression wave and sharp increase in the peak gradient of the head wave,thus inducing the sonic boom phenomenon.When a sonic boom occurs,the peak value of micro-pressure wave at the tunnel portal is generally high,and the measured peak value can exceed 120 Pa.The decibel value of the noise increases instantaneously at the moment of the sonic boom,which is up to 45 dB(A)higher than that of the ambient noise.Opening the inclined shaft in the tunnel or adding aerodynamic openings to the portal buffer structure can assist in alleviating the sonic boom phenomenon to a certain extent.The measured maximum decrease in the peak value of micro-pressure wave at the tunnel portal after opening the inclined shaft is about 28.5%.
high speed railwaylong tunnelsonic boomcompression wavemicro-pressure wavenoise
NETL
NSTL
万方数据
