Perforated exit regions for the reduction of micro-pressure waves from tunnels

TY - JOUR

T1 - Perforated exit regions for the reduction of micro-pressure waves from tunnels

AU - Wang, Honglin

AU - Vardy, Alan E.

AU - Pokrajac, Dubravka

PY - 2015/11

Y1 - 2015/11

N2 - The effectiveness of long, perforated exit regions in reducing pressure disturbances from railway tunnels is assessed. Such disturbances always occur, but their amplitudes are usually small. For the particular case of high speed trains, they can reach levels that would cause annoyance in the absence of suitable counter-measures. This risk is especially large in the case of long tunnels. The mechanisms causing the disturbances are described and the potential effectiveness of perforated exit regions as a counter-measure is demonstrated. It is shown that the effectiveness is sensitive to the number, size and distribution of pressure relief holes along the exit region, but that the most important parameter is the combined area of all of the holes. This parameter controls the balance between external disturbances alongside the perforated region and disturbances beyond the exit portal. It is also shown that the amplitudes of the external disturbances are strongly dependent upon the amplitude and duration of wavefronts arriving at the exit region as well as upon their steepness. This contrasts with the behaviour found for tunnels with simple exit portal regions.

AB - The effectiveness of long, perforated exit regions in reducing pressure disturbances from railway tunnels is assessed. Such disturbances always occur, but their amplitudes are usually small. For the particular case of high speed trains, they can reach levels that would cause annoyance in the absence of suitable counter-measures. This risk is especially large in the case of long tunnels. The mechanisms causing the disturbances are described and the potential effectiveness of perforated exit regions as a counter-measure is demonstrated. It is shown that the effectiveness is sensitive to the number, size and distribution of pressure relief holes along the exit region, but that the most important parameter is the combined area of all of the holes. This parameter controls the balance between external disturbances alongside the perforated region and disturbances beyond the exit portal. It is also shown that the amplitudes of the external disturbances are strongly dependent upon the amplitude and duration of wavefronts arriving at the exit region as well as upon their steepness. This contrasts with the behaviour found for tunnels with simple exit portal regions.

KW - Counter-measures

KW - Micro-pressure wave

KW - Perforated exit region

KW - Pressure gradient

KW - Rail tunnel

KW - Sonic boom

KW - Wavefront steepness

UR - https://www.scopus.com/pages/publications/84942515412

U2 - 10.1016/j.jweia.2015.07.015

DO - 10.1016/j.jweia.2015.07.015

M3 - Article

AN - SCOPUS:84942515412

SN - 0167-6105

VL - 146

SP - 139

EP - 149

JO - Journal of Wind Engineering and Industrial Aerodynamics

JF - Journal of Wind Engineering and Industrial Aerodynamics

ER -