Large air chambers for rail tunnel exit regions

TY - GEN

T1 - Large air chambers for rail tunnel exit regions

AU - Vardy, Alan E.

AU - Liu, Feng

AU - Pokrajac, Dubravka

N1 - Funding Information: National Natural Science Foundation of China (grant no. 52002265). Copyright: © Framatome BHR Ltd 2022 ISAVFT19

PY - 2022/10

Y1 - 2022/10

N2 - The purpose of this paper is to present an assessment of the potential for using large air chambers inside enlarged exit regions of tunnels instead of using long extensions outside tunnel entrances. The target is to prevent the emission of unacceptable micro-pressure waves (MPWs) regardless of the steepness of pressure waves reaching the special exit region, even when no counter-measures are implemented further upstream. The study is complementary to previous work in which multiple small air chambers are assumed to be distributed along a tunnel, under walkways, etc. It is found that exit regions with large chambers could be effective for wavefronts longer than about two tunnel diameters, but probably not for wavefronts shorter than about one tunnel diameter. A possible way of incorporating large chambers in tunnel end regions is hypothesised.

AB - The purpose of this paper is to present an assessment of the potential for using large air chambers inside enlarged exit regions of tunnels instead of using long extensions outside tunnel entrances. The target is to prevent the emission of unacceptable micro-pressure waves (MPWs) regardless of the steepness of pressure waves reaching the special exit region, even when no counter-measures are implemented further upstream. The study is complementary to previous work in which multiple small air chambers are assumed to be distributed along a tunnel, under walkways, etc. It is found that exit regions with large chambers could be effective for wavefronts longer than about two tunnel diameters, but probably not for wavefronts shorter than about one tunnel diameter. A possible way of incorporating large chambers in tunnel end regions is hypothesised.

KW - Counter-measures for MPWs

KW - tunnel exit regions

KW - air chambers

KW - wavefront steepness

KW - wavefront damping

M3 - Conference contribution

SP - 185

EP - 200

BT - Proceedings of the 19th International Symposium on Aerodynamics, Ventilation & Fire in Tunnels – Brighton, United Kingdom

PB - Framatome BHR

T2 - 19th International Symposium on Aerodynamics, Ventilation & Fire in Tunnels

Y2 - 28 September 2022 through 30 September 2022

ER -