Numerical Simulation Study of Effect of Tunnel Slope on Smoke Propagation

Tunnel slope is an important factor affecting smoke spreading for a stopped subway train on fire. In this paper, a multi-scale method where one-dimensional (1D) network is coupled with three-dimensional (3D) field simulation is used to calculate smoke and temperature distributions for a fire occurred in the middle part of the subway train in tunnel. The tunnel slopes of 0‰, 12‰, 21‰ and 30‰ are considered. By comparing the temperature distribution in a condition with natural ventilation and with 2 m/s longitudinal ventilation, we comprehensively analyzed temperature, smoke spread characteristics. Results show that tunnel slope has a great influence on temperature and smoke profile when slope is higher than 12‰. The temperature at 1.8m would exceed the safe limit of 60°C at 60 s after fire ignition. The larger the slope, the higher temperature would be in the train carriage. For a train fire scenario with natural ventilation, within initial 120 s period the train compartment could keep a safe evacuation condition. This research would provide reference for making right evacuation plan of subway tunnel fire.