Evaluating the impact of tunnel slope on critical velocity and confinement velocity in metro tunnel carriage fires

Zhihe Su, Yanfeng Li, H. Zhong, Junmei Li, Boyu Li, Siyan Kang, Y. Huang

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Abstract

Smoke control within metro tunnels stands as a pivotal measure in ensuring both the orderly evacuation and safety of passengers. This study investigated the critical velocity and confinement velocity in inclined metro tunnel fires via model-scale experiments. The tunnel slope varied from 2 % ∼ 8 % and four fire heat release rates of 2.29 kW, 3.44 kW, 4.59 kW and 5.74 kW. Results show that the confinement velocity and critical velocity monotonically increase with the heat release rate and tunnel slope. The confinement velocity Vconf was notably affected by the equivalent fire source Qu. The natural exponential function could effectively express the relationship between Q* and Qu*, with the correction factor of tunnel slope utilized to adjust the expression. A new model for critical velocity and confinement velocity was characterized by considering the tunnel slope and heat release rate. Comparative results indicated that the optimizing confinement velocity was significantly lower than that defined in previous studies, while the proposed critical velocity ratio aligns well with findings from prior research. This study provides valuable insights into the design of smoke control systems customized for fires occurring in trains immobilized within inclined underground tunnels.
Original languageEnglish
Article number106141
Number of pages12
JournalTunnelling and Underground Space Technology
VolumeVolume 154
DOIs
Publication statusAccepted/In press - 9 Oct 2024

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