Study On Fire Smoke Flow Characteristic And Control Method In Subway Tunnel

With the rapid development of China's economy and society,China's road construction shows a flourishing sight,more and more subway tunnels appear in the city.Fire is a problem that needs important concern during the use of subway tunnels.Because the subway tunnel is buried in the underground,once the fire in the interval tunnel,the resulting toxic fumes and heat accumulation,will seriously affect the safety of personnel and the structure of the tunnel,so the development of the tunnel flue gas spreading law and control research is the necessary research topic of tunnel safety.In recent years,many experts and scholars have carried out related researches on the tunnel fire smoke spreading and the tunnel structure stability under fire,aiming at the present situation and shortcomings of the research,the following aspects are researched.Through the similarity criterion,the model of shrinking Metro interval Tunnel is established and the fire tests are carried out on the basis of this paper,and the longitudinal temperature data and the flue gas layer data are obtained by conducting different power experiments.Through the processing of data and the analysis of the longitudinal temperature distribution of the vault under different sources of ignition power,the maximum temperature rise of longitudinal flue gas is roughly exponential attenuation,and it is basically no longer reduced at certain distance from the fire source.In order to verify the feasibility of the fire simulation software for conducting tunnel fire experiment,using FDS to establish the same working condition as the experimental condition,and to model 1:1 models,the maximum temperature of the tunnel vault,the stable thickness of flue gas layer and the longitudinal temperature distribution of vault were analyzed.The results show that the reasonable simulation parameters are set up and the data obtained from the model experiments are basically consistent,and the study of the tunnel fire related with FDS is scientific and feasible.By combining the model with the maximum temperature distribution of the longitudinal roof,the maximum longitudinal temperature distribution model of tunnel roof was obtained.Combined with engineering practice,the fire model of different ignition power and longitudinal wind speed is established and simulated,and the flue gas spread and the temperature distribution of flue gas are obtained under the condition of natural ventilation and FDS.By setting up the wind speed value of different longitudinal ventilation in tunnel and analyzing the results,the relationship between the longitudinal wind velocity and the backflow length of flue gas and the relationship between the critical wind speed and the dimensionless heat release rate are obtained,and finally the critical wind velocity of reflux is obtained.This paper uses theoretical analysis,the similarity criterion Experiment and the FDS simulation research method,and unifies the related engineering practice to the subway tunnel fire smoke spread law and the control method has carried on the research,emphatically analyzed the flue gas layer top longitudinal temperature distribution and the longitudinal wind speed to the flue gas spread correlation parameter influence.The research results in this paper can provide a theoretical basis for the study of flue gas control and personnel safety in Metro Tunnel fire.