Study On Available Time Model Of Fire Evacuation In Immersed Tube Tunnel

In recent years,my country’s tunnel construction technology has developed rapidly,high-quality immersed tube tunnels have continuously emerged,and their length and construction scale have also been increasing.While these long tunnels improve travel efficiency and economic benefits,they also bring certain safety operation challenges,especially tunnel fire accidents that endanger public lives and property safety.The time available for evacuation of personnel is an important factor in evaluating safety,and there are few studies on the time of evacuation of personnel in immersed tube tunnel fire.Therefore,it is particularly important to carry out systematic research on the time available for evacuation of personnel in immersed tube tunnel fire.This dissertation takes as the research object the time of temperature,visibility,CO concentration data reaching the dangerous value under different fire scenarios of the immersed tube tunnel.Through theoretical analysis,physical experiment and simulation experiment,study the temperature field and smoke field in the cave: the time value data of temperature,visibility,and CO concentration respectively reaching the dangerous value,and the law of its change with the scale of combustion and longitudinal wind speed.The main research contents are as follows:(1)Analyzed the tunnel combustion theory and its influence on the safety evacuation of personnel.When a fire occurs in a tunnel,the main control factors for the impact of fire products on the evacuation: the degree of damage to tunnel users by the temperature in the tunnel;the visibility in the tunnel affects the evacuation rate of the stranded personnel;the toxic gas in the tunnel is a direct impact on the evacuation fatality rate of the fire personnel factor.(2)The immersed tube tunnel fire scene model was established with FDS software to simulate the temperature field and smoke field under different combustion scales and different longitudinal wind speeds of the tunnel.The simulation calculation results were verified and compared with the 1:1 physical tunnel fire test data,and it was found The difference between the two is small and the change law is the same,which shows that the results of the tunnel fire numerical simulation calculation using the parameters set by the FDS software in this paper are reliable.(3)Through the single-factor method,the time variation law of the temperature,visibility,and CO concentration at the safety height(2.0m)of the tunnel personnel at the safety height(2.0m)of the tunnel personnel under different combustion scales and different longitudinal ventilation wind speeds in the fire scene was studied separately.The study found that,With the increase of the tunnel fire combustion scale,the available time for safe evacuation of personnel decreases exponentially,and the functional analytical formula of the available time with the increase of the combustion scale at different wind speeds is fitted.With the increase of tunnel fire longitudinal ventilation wind speed,the available time for safe evacuation of personnel presents a polynomial change,and the functional analytical formula of the available time with the increase of longitudinal wind speed under different combustion scales is fitted.(4)Using the multi-factor method to analyze the combustion scale-longitudinal wind speed bivariate,the available time law for the temperature value of the temperature field and the visibility value in the smoke field to reach the safety height hazard value of the personnel is respectively studied,and the following two variables are respectively fitted.The available time function analytical formula of,obtains the available time model of safe evacuation under the influence of combustion scale-longitudinal wind speed bivariate.