Investigation of the fire hazard of underground space fire scenarios in urban metro tunnels under natural ventilation: Analysis of the impact of tunnel slope on smoke back-layering length

作者：Zhihe Su, Yanfeng Li, Hua Zhong, Junmei Li, Shi Qing Yang, Tianmei Du, Youbo Huang · 发表于：Building Services Engineering Research and Technology · 年份：2023 · DOI：10.1177/01436244231223045 · 被引用次数：7 · 研究领域：Fire dynamics and safety research、Evacuation and Crowd Dynamics、Fire effects on ecosystems

The smoke back-layering length is a crucial parameter for evacuating people in both road and subway tunnel fires. This study investigates the fire hazard induced by carriage fire in inclined metro tunnels under natural ventilation. The parameter ‘transition slope’ is defined to measure the smoke flow from the carriage head in the upstream direction to the tunnel or not due to the stack effect of the tunnel slope. The aim of this paper is to analyse the effects of changes in cross-section, downstream length, tunnel slope, and carriage side-door coupling on smoke behaviour characteristics by experiment and simulation methods. A piecewise function expression between dimensionless smoke back-layering length, downstream length, and tunnel slope for carriage fires in an inclined tunnel under natural ventilation is proposed by theoretical analysis. At the same time, a 1:15 scale model experiment was conducted to initially analyse the characteristics of smoke movement. Following this, full-scale numerical simulations were employed to complement the model experiment and quantify the principles governing smoke movement. The experimental results show that the tunnel slope has a significant effect on the smoke back-layering length. In contrast, the influence of the heat release rate was found to be relatively minor. In addition, simulation results show that the tunnel slope has no significant effect on the smoke back-layering length when the fire location is approximately 20 m from the t...