Study On Smoke Control System With The Effect Of Piston Wind In Subway Tunnel

The subway system is a landmark project in modern city, the fire in which has the samefeatures with underground projects and tunnels. There is piston effect in subway, which isexacerbated as the speed raising and the interval time between two subway trains gettingshorter in recent years, making the fire risk increased.To protect people’s safety better, it wasresearched about the influence of piston effect to the fire smoke movement and control systemin this paper.Firstly, based on the subway fires happened in the history as well as the experimentalresearchs, it was concluded about the fire features in subway. Some of the key parametersvalues were given for the performance-based fire engineering design. The piston windvelocity and pressure were analyzed in three ways, the fluid dynamics, ANSYS CFXsimulation and Beijing subway test. Secondly, the subway tunnel smoke control systemrequirements were summarized. For natural smoke exhaust system, it was proposed based oncodes and the experience of Chengdu subway design. For mechanical smoke exhaust system,transverse and longitudinal smoke control systems were introduced. And an example aboutsmoke control system design in tunnel was given, and CFD simulation result was compared tothe test record, which was aimed to prove the reliability of CFD simulation. Thirdly theevacuation was simulated with STEPS. It took more than10minutes to escape from the trainzone for all passengers, which proved the necessity of control the critical velocity inlongitudinal smoke control system. Finally, for the most often used longitudinal smokecontrol system, subway train and electric equipment fires were simulated to test the reliabilityof the critical wind velocity with the value of2m/s in the piston effect, and3.5m/s criticalvelocity is suggested for the train with the length of one carriage.