The behaviour of long entrance hoods for high speed rail tunnels

A. E. Vardy, R. Sturt, C. J. Baker, D. Soper

Research output: Chapter in Book/Report/Conference proceedingConference contribution

5 Citations (Scopus)

Abstract

Micro-pressure waves (MPWs, sometimes known as sonic booms) must be mitigated in the design of high speed rail tunnels, typically by the use of perforated tunnel entrance "hoods". These reduce the gradients of the pressure waves caused by train entry and thereby reduce the amplitudes of the MPWs emitted from tunnel exits. The required length of an entrance hood depends strongly on the train speed because the pressure gradient at the tunnel entrance varies with the cube of the train speed. Typical entrance hoods on existing tunnels for speeds of 250-300 km/h are up to 50 m long As the design speeds for new railways increase to 350 km/h or more, the hoods must become significantly longer. This paper presents an investigation into suitable designs for 100 m long perforated entrance hoods. It is shown that a simple configuration with a tapered cross sectional area and uniformly distributed openings gives close to the best that is practicably possible. This configuration differs markedly from that used for typical hoods on existing tunnels. The presentation begins with a theoretical assessment that enables the overall behaviour to be described and understood. This is followed by comparisons with detailed measurements in a 4% scale model. A valuable spin-off benefit is a provisional conclusion that the performance of such hoods can be predicted with reasonable accuracy using simple ID methods that are already used widely for other purposes of tunnel design.

Original languageEnglish
Title of host publicationBHR Group - 16th International Symposium on Aerodynamics, Ventilation and Fire in Tunnels 2015
PublisherBHR Group
Pages449-466
Number of pages18
ISBN (Electronic)9781510813748
Publication statusPublished - 2015
Event16th International Symposium on Aerodynamics, Ventilation and Fire in Tunnels 2015, ISAVFT 2015 - Seattle, United States
Duration: 15 Sep 201517 Sep 2015

Conference

Conference16th International Symposium on Aerodynamics, Ventilation and Fire in Tunnels 2015, ISAVFT 2015
Country/TerritoryUnited States
CitySeattle
Period15/09/1517/09/15

ASJC Scopus subject areas

  • Safety, Risk, Reliability and Quality
  • Civil and Structural Engineering
  • Building and Construction

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