Study On Fire Smoke Flow Characteristics And Personnel Evacuation In Subway Interval Tunnel

With the increase of urban population and the rapid development of urban economy,major cities in China have begun to increase the construction of urban rail transit.The construction of subway alleviates the pressure of urban traffic and reduces the use of urban ground space.It has the effects of land conservation,energy conservation and environmental protection.Since the subway is mainly built underground and the interval tunnel is the passage for subway to transport passengers,the rescue and evacuation of personnel will be very difficult once the metro vehicle is forced to stay in the narrow interval tunnel in case of fire and other emergencies.Considering the major fire accidents that have occurred since the construction of the subway,it is necessary to study the subway fire and emergency evacuation of personnel.Compared with the spacious evacuation passage and fire protection facilities of subway station,subway tunnel is too closed and narrow,and it is more difficult to evacuate and rescue people after fire,so it is more hazardous.This article will focus on the following aspects:(1)Through practical investigation and consulting relevant documents,we know the types of subway tunnels,the ventilation and smoke exhaust methods of tunnels at home and abroad.At the same time,we investigate domestic B-type subway trains to understand structure and thermophysical parameters of B-type train and main constituent materials,so as to build models of interval tunnels and B-type subway train.(2)Based on the investigation data,the model of interval tunnel and B-type metro train is established in Pyrosim.The relevant material parameters,the opening modes of train passenger compartment doors,the ventilation and smoke exhaust modes of tunnel are set up.The fire source is located in the middle gangway of the B-type metro vehicle(the most dangerous fire condition of vehicle),and the corresponding thermocouples and smoke sensors are set in the carriage and the evacuation platform to monitor changes of fire parameters such as smoke visibility,temperature,and CO concentration.This paper simulates the fire in the middle gangway of the B-type metro vehicle,discusses the influence of different tunnel geometric characteristics and the opening modes of train passenger compartmentdoors on the flow characteristics of fire smoke,and analyses the fire parameters in the carriage and the lateral evacuation platform,which lays a foundation for the study of personnel evacuation.(3)Based on the simulation results of fire smoke flow characteristics and the investigation of passenger types in domestic metro,the evacuation simulation software Pathfinder is used to establish the corresponding Personnel evacuation model and the passenger evacuation process in the tunnel is simulated under fire conditions.Through the personnel evacuation simulation under two different guidance modes,it is concluded that under the first mode of evacuation guidance,that is to say,all passengers in the train carriages can use the evacuation platform equally for evacuation,and the overall evacuation efficiency of the train is low,the overall evacuation time of the train is 17min16 s.In the second mode of evacuation guidance,that is to say,the passengers of the last three carriages have priority to use the lateral evacuation platform for evacuation,and the overall evacuation efficiency of the train is higher,the overall evacuation time of the train is 15min48 s.At the same time,it is known that the width of the evacuation platform has an important impact on the evacuation efficiency,and research may provide advice and guidance for personnel evacuation in emergency situations.