Abstract:Based on a typical high-altitude single-hole, double-track railway tunnel emergency rescue station, the smoke spread, temperature, and visibility distribution of fire in a tunnel under different smoke extraction volumes and natural wind conditions were systematically studied using FDS. The recommended value for the optimal mechanical smoke extraction volume was obtained, and suggestions for personnel escape and smoke control were provided. The results showed that when there was natural wind, some smoke entered the communication passage during natural smoke extraction, which was not conducive to personnel escape. During mechanical smoke extraction, as the smoke extraction volume increased, the smoke spread distance was significantly reduced, but the reduction in the tunnel vault temperature was limited. When the smoke extraction volume was set to 300 m3/s, regardless of the presence of natural wind, the temperature at the characteristic height of the tunnel was below 60 ℃, the visibility was greater than 10 meters, and the smoke was mainly concentrated at the top of the tunnel, with a clear boundary between it and the lower layer of air, making personnel evacuation possible in a safe condition. Suggestions for personnel escape: When there is no natural wind, personnel should escape through the passage with a communication smoke extraction duct or the nearest evacuation passage. Smoke control strategy: It is recommended to introduce an appropriate amount of longitudinal mechanical ventilation, blowing from the side without a smoke extraction duct to the side with one, which helps shorten the smoke spread length and creates more favorable conditions for personnel escape. Consider shutting down the smoke extraction fans located farther from the fire source to improve the efficiency of the entire smoke extraction system.