Smoke control

Abstract

As a representative form of public transportation, subway system is undertaken to satisfy constantly increasing transport needs and developed commonly in many big cities. Among several catastrophes in subwaystations, including fire, flood, earthquake, explosion, toxic gas leakage etc., fire is the most threateninghazard to passengers. Subway fires had caused huge casualties and property losses during the past decades. With the development of metro line network, more and more transfer stations appeared. Compared with the general subway station, smoke control system of transfer station has its particularity and complexity. A typical cross-shaped metro transfer station is used as an example for the study. Effect of two different schemes of ventilation and smoke control in extreme conditions in which multiple fires happen simultaneously on both platforms in the transfer station are studied by using numerical simulation method. In fire scenario No.1, airis supplied in underground one while independent smoke control is taken in underground two and three. In scenario No.2, based on scenario No.1, tunnel fans are used to assist in smoke control by opening screen door. Fire source is designed for t2 rapid fire with peak 2MW. The results show that, smoke spread in second underground floor can be controlled effectively by both schemes, the measure used in scenario 2 effectively raises the wind speed downward the stairs while lower temperature around stairs, so that stairs round fire sourcecan be used as emergency evacuation passages for a longer time, guaranteeing a better smoke control performance in interchange station. Connecting the underground third floor with tunnel ventilation system by openingPSD can increase the downward air flow velocity and decrease the air temperature at staircases near the fire. Period during which the staircase near fire can be used for evacuation is increased. Reliable smoke control performance for transfer station can be got.