The Research On Fire Hazard And The Personnel Safety In Tunnel Fire With Different Methods Of Smoke Exhaustion

The main cause of the tunnel fire is the failure of vehicles.The main cause of the casualties is the toxic smoke with high temperature.While the reasonable ventilation and smoke exhaustion are two effective measures to control the spread of fire smoke and reduce its harm to the personnel.First,this paper summarizes the development of the tunnel and the occurrence of the fire accident domestic and overseas.The causes,characteristics,the harm of tunnel fire and the main smoke exhausting mode of tunnel fire are analyzed.Based on a highway tunnel in ZheJiang Province,a small size testing model is established,and the experimental study of tunnel fire under natural ventilation,longitudinal smoke exhaustion and lateral smoke exhaustion is carried out.The variation of C02 concentration and CO concentration with time under different smoke exhausting modes and the effect of mechanical ventilation on CO concentration are analyzed.Then,based on the testing model,a numerical model of tunnel fire is established,and its reliability is verified by comparing the results of numerical simulation with the experimental data.The spatial distribution pattern of CO concentration and temperature in tunnel under vertical and transverse smoke exhausting mode is also analyzed.The theoretical formulas of the maximum flue gas temperature under the vault,the longitudinal ventilation wind speed and the scale of the fire are obtained according to the results.The influence of the rate of smoke exhaustion and the size of exhausting port on the temperature under horizontal smoke exhaustion is analyzed.Meanwhile,The the change of distribution pattern of CO concentration and maximum temperature rise with velocity of gas exhaustion were compared and analyzed under two smoke different exhausting conditions.Finally,the actual tunnel model is established to study the smoke diffusion in the tunnel under different conditions of smoke exhaustion in 20MW fire.The theoretical formula of the maximum flue gas temperature below the vault is modified,and the safe evacuation time is obtained based on the criterion of personnel safety.The Pathfinder evacuation software is used to simulate two conditions of normal traffic and vehicle congestion.The necessary safe evacuation time under two different conditions is obtained and compared with each other to judge whether the safety evacuation criteria can be met.The reasonable horizontal channel space is determined by analyzing the evacuation of personnel under different smoke exhausting modes,which has is of certain guiding significance.