Arc-top tunnel longitudinal ceiling temperature distribution under longitudinal ventilation with different fire-source–side-wall distances

Tunnels have significantly enhanced the convenience of urban development and vehicular travel. However, recurring tunnel fire accidents have become an issue owing to the complex tunnel structure and high traffic flow. This study used a reduced-scale experiment and full-scale fire dynamics simulation to investigate the unique phenomenon of smoke plumes caused by a fire source near the tunnel sidewall under longitudinal ventilation. The correlation between the transverse position of the plume and temperature was examined, and the transverse position of the plume was found to be inconsistent with the temperature trajectory. The attenuation trend of the mid-axis temperature of the tunnel ceiling was explored based on the newly proposed model, and it was concluded that the plume temperature data can be well converged using the proposed method. This study provides a reference for exploring the temperature distribution in arched tunnels when the fire source is near the tunnel sidewall.