| In order to relieve the pressure of urban ground traffic,many cities in China,especially large cities,are actively constructing urban traffic link tunnels,The tunnels have the characteristics of complex structure,large traffic volume and slow traffic speed.Once a fire occurs,rescue is very difficult.In recent years,there have been some achievements in the study of tunnel fires,but the research on fire smoke in semi-transverse ventilation and smoke exhaust mode is still scarce.In order to provide reference for other similar UTLT tunnel ventilation and smoke exhaust design,this article takes a practical UTLT tunnel as the research object,and researches the ventilation and smoke exhaust methods of this type of tunnel.Firstly,use FDS numerical simulation software to study the smoke exhaust schemes at different fire source locations,analyze the fire smoke diffusion characteristics,temperature field,visibility field,and smoke spread range in the tunnel under different fire scenarios,and compare with the fire smoke Comparison of control indicators.Based on the tunnel structure and ventilation and smoke exhaust methods,a physical and mathematical model of numerical simulation is established,and the parameters of vehicle fire scale and growth mode are determined based on the actual types and flows of vehicles.Consult relevant literature to analyze and determine the fire smoke control standards for this type of tunnel in semi-transverse smoke exhaust mode.Then use FDS numerical simulation software to study the smoke exhaust schemes at different fire source locations,analyze the fire smoke diffusion characteristics,temperature field,visibility field,and smoke spread range in the tunnel under different fire scenarios,and compare with the fire smoke Comparison of control indicators.The research results show that:(1)The fire scene at the center point of the straight section of the main tunnel and the center point of the curved section adopts a semi-transverse smoke exhaust mode,and the ventilation exhaust scheme is set as follows:the smoke exhaust volume is 50m~3/s,and the size of the exhaust valve is 3m~2,when 6 smoke exhaust valves are opened,and the interval is24m.In some areas outside the 30m range of fire source,the visibility value at the characteristic height of the human eye in the tunnel is lower than 10m or the temperature at the characteristic height of the person is higher than 60?.The fire smoke control effect has not reached the safety control index.Therefore,the ventilation and smoke exhaust scheme Modifications are required;(2)The fire scene at the ramp section of the entrance and exit adopts the method of vertical ventilation and smoke exhaust,and the minimum longitudinal wind speed value of 2.0m/s is selected as the critical wind speed,so that there is no smoke return in the ramp section of the entrance and exit,which can ensure the safety of personnel evacuation;(3)The fire scene at the intersection of the main tunnel and the ramp.Turn on the axial flow fan at the on-ramp to allow the smoke to be discharged out of the tunnel along the entrance and exit section.Select a minimum longitudinal wind speed of 2.2m/s to ensure that there is no smoke back-flow in the main tunnel section.Finally,the semi-transverse ventilation and smoke exhaust method of the fire scene at the straight section of the main tunnel is used as an example to simulate and analyze the effects of different smoke exhaust rates and different smoke valve settings on the temperature,visibility and spread range of fire smoke in the tunnel.The research results show that the optimized ventilation and smoke exhaust scheme for the straight and curved sections of the tunnel is that the smoke exhaust volume is 60m~3/s,the size of the smoke exhaust valve is 3m~2,and the six smoke exhaust valves are opened,and the distance is 24m.Fire smoke control can meet safety indicators. |
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