Study on the influence of slope on smoke overflow and temperature characteristics of carriages with lateral openings in subway fires

Abstract

This research explores the impact of slope on fire hazards in train carriages with multiple lateral openings in underground tunnel fires. Utilizing FDS software, a comprehensive full-scale fire scenario is simulated to study smoke overflow and temperature distribution in inclined tunnels with slopes ranging from 0 % to 4 % and Heat Release Rates (1 MW–10 MW) under natural ventilation. The study reveals that smoke mainly originates from the upstream end door and the door near the fire source, with smoke overflow from the upstream end door increasing significantly with the slope. Fire power has minimal impact on smoke overflow. When fire power is large, the longitudinal temperature distribution inside the carriage exhibits an overall increasing trend with increasing slope. The maximum carriage temperature decreases steadily with the slope for Q˙ ≤ 5 MW, while the slope has less influence on temperature variation for Q˙ > 5 MW. A modified prediction model is proposed to forecast maximum ceiling temperature during fire scenarios, providing valuable insights for structural fire protection, fire detection, and smoke control in metro areas. This study enhances understanding of smoke movement and temperature distribution in train carriage fires in inclined tunnels, contributing to engineering practices.