| A large number of underwater tunnels have been built successively in China,which are getting longer and longer,and the cross-section is getting bigger and bigger.The construction of underwater tunnels can solve the restrictions of traffic trunk lines crossing rivers and straits,and also alleviate the pressure of urban traffic.However,due to the special structure of tunnels and their relative independence,once an emergency occurs in tunnels,serious casualties,property losses and bad conditions will be caused.Social impact.For rectangular large cross-section super-long underwater tunnel,due to the large space inside the tunnel and the long tunnel,the temperature field and smoke spread are unique when fire occurs in the tunnel.The ventilation,fire prevention and rescue technical scheme and side exhaust flue are inexperienced in China.Based on the Taihu Tunnel project,the Taihu Tunnel has the characteristics of long length,large cross-section and large traffic volume.When rectangular large cross-section tunnel fires occur in non-blocking and blocking conditions,it is necessary to adopt different smoke exhaust and smoke control methods.In view of the possible fire scenarios in this project,the smoke control technology of rectangular large cross-section ultra-long underwater tunnel is studied.Combining with the tunnel structure characteristics,disaster prevention scale,fire characteristics,ventilation and smoke exhaust mode,a reasonable rectangular large cross-section tunnel fire smoke control technology is proposed.Research on fire smoke control technology under normal working conditions and fire smoke control technology under blocking working conditions.The main research contents are as follows:1)Study on heat release rate of tunnel fireAiming at the problem of setting and selecting the fire source scale of rectangular large cross-section underwater tunnel,this paper investigates the heat release rate of tunnel fire both at home and abroad.Based on the experimental results of fire source power of highway tunnel in different areas at home and abroad,and combined with the actual engineering situation of traffic flow and vehicle type of Taihu tunnel,a reasonable fire in Taihu tunnel fire situation is obtained.Source power.2)Determination of reasonable smoke discharge under lateral centralized smoke exhaust modeThe amount of smoke discharged depends mainly on the rate of smoke generation,while the rate of smoke generation in fire mainly depends on the mass flow rate of smoke plume above the fire source.The theoretical smoke volume is calculated by using the smoke generation of axisymmetric and wall plumes.On this basis,the reasonable smoke volume larger than the theoretical smoke volume is selected considering some factors such as air leakage and low smoke exhaust efficiency of the side exhaust system.Then,its rationality is verified by numerical simulation.3)Study on the influence of the distance between side centralized smoke outlets and the number of opening groups of smoke outlets on smoke exhaust effectFor rectangular long tunnel with large cross-section,how to effectively control the spread of smoke after fire,the distance between exhaust outlets and the number of opening groups of exhaust outlets are the key links.Control one of the variables,change the second parameter,and set a variety of working conditions.Through numerical simulation and 1:15 scale physical model test,the reasonable distance between side-wall exhaust nozzles was analyzed.4)Study on the Law of Critical Wind Velocity for Suppressing Flue Gas Reflux under Longitudinal Ventilation and ExhaustThis paper studies the control effect of different longitudinal ventilation rates on smoke spread when tunnel fires occur on different slopes(0%,1%,2% and 3% gradients).The main purpose of this study is to explore the relationship between critical wind speed required to suppress smoke reflux and tunnel slope,so as to provide a reasonable smoke control scheme for Taihu Tunnel under fire conditions.Reference resources. |
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