Research On Escape Mode Of Tunnel Fire Based On Specific Temperature,CO And Visibility

In recent years,tunnel engineering at home and abroad is in a stage of rapid development.However,with the increase in the number of tunnels,tunnel fire safety accidents also emerge in endlessly.Although domestic and foreign scholars have conducted research and analysis on some specific tunnel fire accidents,they have not yet obtained mature theory and engineering experience.Disaster prevention and mitigation and emergency evacuation of tunnels have always been a major problem in the safe operation of tunnels.Therefore,in the event of a tunnel fire,reasonable arrangements for the evacuation of personnel are of great significance to ensure the safety of people’s lives and reduce the operational risks of the tunnel.At the same time,this also provides relevant technical support for the tunnel’s disaster prevention and mitigation and design concepts.This paper takes sanmeiya tunnel as the actual engineering support.Based on the pyrosim software,the numerical simulation models of the tunnel under five specific fire conditions are established,and the variation rules of the temperature,CO concentration and visibility of the sanmeiya highway tunnel under different conditions are discussed.The final conclusion is that the ventilation speed has a great influence on the temperature field,CO concentration field,and smoke field in the sanmeiya tunnel.The purpose of the critical wind speed is to prevent the high temperature smoke from spreading to the upstream of the fire source,and to ensure the escape time of the downstream personnel to the maximum extent.The critical wind speed of sanmeiya tunnel is between 1.2m/s and 1.5m/s under the condition of 20 MW fire.With the help of the video animation of the temperature and visibility changes with time at the height of one person under different working conditions in the tunnel and the CO concentration value at a height at different positions in the tunnel under different working conditions,the fire risk time under various working conditions is obtained.According to the simulation results,it is feasible to establish the evacuation model of sanmeiya tunnel in Pathfinder software by importing FDS model.The evacuation rules of people in the tunnel unde different working conditions can be obtained,and the evacuation time of people under various working conditions can be obtained.By comparing the fire hazard time and the evacuation time,the escape situation of the people in the tunnel under different working conditions is obtained.Propose fire safety measures for working conditions where all personnel cannot be safely evacuated.This paper also evaluates the detention of people under different fire conditions,and provides help for the establishment of a tunnel-like disaster prevention and rescue system.