Study on the Effect of Makeup Air Supplementation on Fire Smoke Control in Subway Tunnel

Makeup air plays an important role in smoke control of building fire. Based on the evacuation behaviour of people in fire environments, makeup air was only supplied in the evacuation passageway in this study. Effects of breathing zone lateral makeup air supplementation and underfloor makeup air supplementation on fire smoke control in subway tunnel were discussed, respectively. It was found that breathing zone lateral makeup air supplementation could prevent part of the smoke from spreading to the evacuation passageway. Due to entrainment, makeup air was mixed with smoke, resulting in the CO concentration that did not meet the relevant evacuation requirements. In addition, breathing zone lateral makeup air supplementation had significant disturbances on the fire and smoke layer. The underfloor makeup air supplementation had fewer disturbances to the fire and smoke layer. However, neither the temperature nor the CO concentration could meet the evacuation requirements. Therefore, breathing zones combined with underfloor makeup air supplementation were applied in this study. The results showed that the combined makeup air supplementation created a relatively safe evacuation passageway, and the temperature, CO concentration, and visibility in the evacuation passageway could all meet the relevant evacuation requirements. This study is expected to provide a new idea for the design of tunnel fire smoke control system.