Research And Application Of Coordinated Control Technology For Traffic Control And Ventilation System In Highway Tunnel Fires

With the vigorous development of highway construction in China,the construction of highway tunnels has also made great progress,and the management department has also improved the requirements for safe operation of tunnels.In recent years,tunnel fire accidents at home and abroad have occurred from time to time,causing major casualties,property losses and serious social impacts due to the special structure and traffic characteristics of tunnels.Carrying out the research on the coordinated control of tunnel fire traffic control and ventilation system can effectively manage and control the traffic and smoke diffusion of the tunnel where the fire is located after the tunnel fire,provide favorable conditions for personnel evacuation,reduce the harm caused by fire accidents,and improve the disaster prevention and mitigation ability of highway tunnels.The research on tunnel fire at home and abroad mainly focuses on critical wind speed,smoke spread characteristics,personnel evacuation and other directions,and there are few studies on comprehensive consideration of traffic and ventilation,this paper relies on the project of Jiangxi Jiulingshan Tunnel,from the perspective of traffic control technology and ventilation control technology,through theoretical analysis,the characteristics of tunnel fire traffic flow under fire accidents are clarified,and the influence of traffic on the ventilation system is analyzed.Using numerical simulation,the critical wind speed of Jiulingshan tunnel fire was studied,and then the coordinated control plan of traffic control and ventilation system was formulated,and finally the coordinated control system software was designed and developed,the main research content is as follows:(1)The tunnel fire is studied in stages by division,and the highway where the tunnel is located is divided into no impact area,impact area and fire tunnel area,and the fire tunnel area is subdivided.According to different combustion vehicle types,the fire grade is divided,and the heat release rate of the ignition source of each grade is clarified.The development stages of tunnel fire are divided into early stage of fire,evacuation stage,fire extinguishing and smoke exhaust stage and recovery stage.(2)According to the traffic flow fluctuation theory,the traffic flow gathering and distribution wave propagation model during the control period and the impact of traffic control on the surrounding road network traffic are analyzed and studied,and the calculation method of the maximum impact range,control time,length of traffic control area and number of vehicles stuck in the cave under the fire accident is summarized based on the Greenshield model.(3)For the Jiulingshan tunnel fire,numerical simulation method is used to obtain the distribution law of temperature,CO concentration and visibility under the condition that the emergency ventilation system fails and the daily operation ventilation wind speed is used in the tunnel,which clarifies the importance of the emergency ventilation system.By designing eight typical fire scenarios,the calculation results of Kennedy’s formula are 28% — 37% smaller than the numerical simulation results,and Wu and Baker’s formula is more consistent with the numerical simulation results,and the conclusion that the main influencing factor of critical wind speed under the determined tunnel is the heat release rate of the fire source.Due to the stationary vehicle at the ignition source,the cross-sectional area of the tunnel is changed,which will also have an impact on the critical wind speed,and the larger the blocking area,the smaller the critical wind speed value,and the higher the height under the same blocking area,the smaller the critical wind speed.Based on the number of vehicles stranded in the cave,it is obtained that when a 24 MW fire occurs in the Jiulingshan Tunnel,the critical wind speed is positively correlated with the average vehicle speed in the cave.(4)According to the different fire scenarios,formulate a traffic control plan for the fire tunnel area,clarify the length of the affected area,and formulate a traffic control plan for the affected area.According to the critical wind speed of 8 typical fire scenarios,the number of jet fans turned on is calculated.Combined with the difference in fire source location,fire source heat release rate and fire development stage,the coordinated control plan of fire traffic control and ventilation system of Jiulingshan Tunnel was formulated.(5)Using J2 EE architecture based on three-layer B/S distribution mode,the software design and development of the coordinated control system of traffic control and ventilation system of Jiulingshan Tunnel are carried out,and the role of each functional module is introduced.