Numerical Investigation of Back-Layering Length and Critical Velocity in Curved Subway Tunnels with Different Turning Radius

Numerical Investigation of Back-Layering Length and Critical Velocity in Curved Subway Tunnels... Curved tunnels are inevitable subjected to the city underground geological conditions. Due to the catastrophic consequence of tunnel fires with high population density, the related researches on fire safety of curved tunnel are full of significance. Therefore, a series of curved subway tunnels with turning radius of 300–1000 m were investigated numerically by FDS 5.5.3 in terms of the smoke back-layering length and critical ventilation velocity under the heat release rate of 5–10 MW. Theoretical analysis shows that the curved tunnel with the local resistance has an advantage of preventing smoke spreading compared with straight tunnel. The simulation results also indicated that both the smoke back-layering length and the critical ventilation velocity increased with the rising turning radius, and the straight tunnel has the largest values. In fact, the local resistance impact factor for the smoke back-layering length in the curved tunnel, $$ k_{f} $$ k f , was controlled by turning radius $$ R $$ R and ventilation velocity $$ V $$ V . The dimensionless critical velocity increased slightly from $$ 0.638Q^{*1/3} $$ 0.638 Q ∗ 1 / 3 to $$ 0.669Q^{*1/3} $$ 0.669 Q ∗ 1 / 3 when the turning radius increased from 300 m to 1000 m. Without considering the influence of turning radius (local resistance), previous models cannot be applied to the curved tunnel. The improved prediction models about smoke back-layering length and critical velocity with the factor of turning radius could provide a technical guideline for the tunnel ventilation designs. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Fire Technology Springer Journals

Numerical Investigation of Back-Layering Length and Critical Velocity in Curved Subway Tunnels with Different Turning Radius

Numerical Investigation of Back-Layering Length and Critical Velocity in Curved Subway Tunnels with Different Turning Radius

Fire Technology, 53, 1765–1793, 2017 2017 Springer Science+Business Media New York. Manufactured in The United States DOI: 10.1007/s10694-017-0656-0 Numerical Investigation of Back-Layering Length and Critical Velocity in Curved Subway Tunnels with Different Turning Radius Shaogang Zhang, Hui Yang, Yongzheng Yao, Kai Zhu, Yong Zhou and Xudong Cheng*, State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei 230026 Anhui, People’s Republic of China Long Shi, Center for Environmental Safety and Risk Engineering, Victoria University, Melbourne, VIC 8001, Australia Received: 31 August 2016/Accepted: 19 April 2017 Abstract. Curved tunnels are inevitable subjected to the city underground geological conditions. Due to the catastrophic consequence of tunnel fires with high population density, the related researches on fire safety of curved tunnel are full of significance. Therefore, a series of curved subway tunnels with turning radius of 300–1000 m were investigated numerically by FDS 5.5.3 in terms of the smoke back-layering length and critical ventilation velocity under the heat release rate of 5–10 MW. Theoretical analysis shows that the curved tunnel with the local resistance has an advantage of preventing smoke spreading compared with straight tunnel. The simulation results also indicated that both the smoke back-layering length and the critical ventilation velocity increased with the rising turning radius, and the straight tunnel has the lar- gest values. In fact, the local resistance impact factor for the smoke back-layering length in the curved tunnel, k , was controlled by turning radius R and ventilation 1=3 velocity V . The dimensionless critical velocity increased slightly from 0:638Q to 1=3 0:669Q when the turning radius increased from 300 m to 1000 m. Without consid- ering the influence of turning radius (local resistance), previous models cannot be applied to the curved tunnel. The improved...
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Publisher
Springer US
Copyright
Copyright © 2017 by Springer Science+Business Media New York
Subject
Engineering; Civil Engineering; Classical Mechanics; Characterization and Evaluation of Materials; Physics, general
ISSN
0015-2684
eISSN
1572-8099
D.O.I.
10.1007/s10694-017-0656-0
Publisher site
See Article on Publisher Site

Abstract

Curved tunnels are inevitable subjected to the city underground geological conditions. Due to the catastrophic consequence of tunnel fires with high population density, the related researches on fire safety of curved tunnel are full of significance. Therefore, a series of curved subway tunnels with turning radius of 300–1000 m were investigated numerically by FDS 5.5.3 in terms of the smoke back-layering length and critical ventilation velocity under the heat release rate of 5–10 MW. Theoretical analysis shows that the curved tunnel with the local resistance has an advantage of preventing smoke spreading compared with straight tunnel. The simulation results also indicated that both the smoke back-layering length and the critical ventilation velocity increased with the rising turning radius, and the straight tunnel has the largest values. In fact, the local resistance impact factor for the smoke back-layering length in the curved tunnel, $$ k_{f} $$ k f , was controlled by turning radius $$ R $$ R and ventilation velocity $$ V $$ V . The dimensionless critical velocity increased slightly from $$ 0.638Q^{*1/3} $$ 0.638 Q ∗ 1 / 3 to $$ 0.669Q^{*1/3} $$ 0.669 Q ∗ 1 / 3 when the turning radius increased from 300 m to 1000 m. Without considering the influence of turning radius (local resistance), previous models cannot be applied to the curved tunnel. The improved prediction models about smoke back-layering length and critical velocity with the factor of turning radius could provide a technical guideline for the tunnel ventilation designs.

Journal

Fire TechnologySpringer Journals

Published: Apr 25, 2017

References

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