Abstract: The effectiveness of natural smoke exhaust mode in a large underground pedestrian district was researched by hot smoke test. The area of fire source was 2 m2 and the power of it was about 1 500 kW for the 3 fire locations. The results showed that most of the smoke was discharged to the outdoor through the natural smoke outlet above the fire source under the action of thermal buoyancy in the natural smoke exhaust mode, leaving a small amount of flue gas gathered and subsided only in local area. During the simulated evacuation time, the evacuation path and evacuation exit had high visibility, and the overall smoke control and exhaust effect was obvious. The temperature change of the flue gas flow along the path of fire source has no obvious influence on the evacuation behavior of personnel.

Key words: fire, underground pedestrian block, semi- outdoor space, natural smoke exhaust, hot smoke test