Simulation Of Highway Tunnel Fire Based On Water Mist And Emergency Evacuation Research For Vehicle Occupants

With the deepening of the strategy of transportation power,highway tunnel construction in China has made remarkable achievements,greatly improving the efficiency of vehicle operation,but tunnel fires also occur from time to time.Fire prevention and control of highway tunnel and emergency evacuation of operating vehicles and passengers have become a hot issue.Currently,scholars at home and abroad mainly focus on fire heat release rate,critical wind speed,development law,smoke exhaust mode and so on.With the continuous development and maturity of water mist fire extinguishing system in the field of building fire extinguishing,it is expected to be applied in the field of highway tunnel fire.However,the influencing factors and fire development rules of water mist fire extinguishing system applied in highway tunnel fire are not clear.Therefore,it is necessary to analyze the influencing factors and rules of water mist fire extinguishing system applied in highway tunnel fire,and on this basis,to study the effective evacuation of driving vehicles and passengers,so as to solve the fire safety emergency and driving of highway tunnel scientifically.The problem of personnel escape provides theoretical support.In this study,the Pyrosim simulation software was used to establish the model based on the actual tunnel size.By setting up three factors affecting the water mist fire suppression efficiency of different longitudinal wind speed,water mist spray flow and spray cone angle,the development law of fire parameters such as smoke,temperature,CO and visibility of highway tunnel fire was simulated,and the feasibility of water mist fire extinguishing system applied to highway tunnel fire was evaluated.In the aspect of evacuation,the fire scene under the action of water mist is introduced into Pathfinder to simulate the evacuation time and path.By comparing the available evacuation time and required evacuation time of drivers,it can be judged whether the drivers of running vehicles can escape safely under the action of water mist fire extinguishing system.The simulation results show that the main fire parameters affecting the evacuation of driving passengers are temperature,smoke and visibility.The water mist has better control effect on temperature,CO and visibility,and the effect is best when the spray flow rate is 20L/min and the spray cone angle is 120 degrees.In the aspect of fire development law,flue gas settles downward from the top of tunnel along the tunnel wall in the transverse distribution,and the difference of temperature and CO concentration in the transverse distribution is not obvious.Longitudinally,the flue gas layer is higher near the fire source,and the flue gas layer settles at a distance.At the same time,the distance between flue gas and CO is longer than the temperature.Based on the above rules,the evacuation process should be along the center of the tunnel,near the fire source should be rapid evacuation,and then lower body posture for evacuation.Based on the law of fire development and the law of emergency evacuation of driving personnel,this paper provides a theory for tunnel construction,safe operation,road transportation safety guidance and education.