| Urban Traffic Link Tunnel(abbreviation as UTLT)is a new type of urban underground public transport system.Compared with the normal highway tunnel,UTLT has a complicate structure,large vehicle flow and steep slope,which make the internal airflow organization more complex and the concentration distribution of pollutants may be higher.At present,the concentration distribution characteristics of the pollutants and the operation strategy of ventilation system in UTLT have not been studied yet.Therefore,this thesis choose the UTLT of Chongqing Monument for Liberation as the research object,and studied the distribution characteristics of the concentration of the internal pollutants and the operation strategy of the mechanical ventilation system under the serious traffic jam.The pollutant concentration and wind speed in Chongqing Bayi tunnel were measured and a numerical model was established according to the geometric size and traffic flow of Bayi tunnel which based on the field measurement.By comparing the simulation results with the measured results,the simulation method and the reliability of the pollution source setting method are verified.At the same time,the wind speed field of UTLT of Chongqing Monument for Liberation was measured,to ensure the boundary condition of the simulation model is correct.The full-scale tunnel model of the UTLT of Chongqing Monument for Liberation is established by using Fluent17.2 numerical simulation software.By comparing with the shut down and fully operation tunnel ventilation system,the distribution characteristics of the pollutant concentration in the tunnel and the influence of different ventilation system operation strategies on the concentration distribution of pollutants were obtained,the operation scheme of the UTLT ventilation system was determined.Suggestions are made for the design of UTLT tunnel ventilation system operation strategy in the future. |
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