Fire Smoke Transport in Inclined Evacuation Passages of Deep-Buried Metro Stations: A Reduced-Scale Experimental Study

To investigate fire-induced smoke transport in continuous inclined evacuation passages of deep-buried metro stations, a 1:15 reduced-scale model was constructed according to the Froude similarity criterion. Experiments were conducted using nominal fire source powers of 3, 8, and 13 kW under different ventilation conditions and passage configurations. Without ventilation, the smoke-front arrival time at the outlet of the fourth inclined section decreased from 385 s at 3 kW to 35 s at 13 kW. Increasing fire source power also increased the temperature difference between the ceiling and the representative occupant height. Natural ventilation reduced temperatures near the fire source but caused smoke to reach downstream sections earlier. Under the 13 kW condition, temperatures at the remote measurement point increased under natural ventilation. Increasing the number of passage sections delayed smoke arrival at the passage end under the 3 kW condition, whereas the effect was limited at 13 kW. These findings provide experimental data for smoke-control design and evacuation safety assessment in deep-buried metro stations.