Research On Ventilation Calculation Method Of Urban Traffic Link Tunnel In Station

As a now type of underground transportation hub, Urban Traffic Link Tunnel(UTLT) continue to rise with the urbanization’ development of China. With the main function to bypass the passengers from traffic station,UTLT has it’s own characteristics, as compared with traditional underground garage, passengers and vehicles are continuous in UTLT; as compared with Highway Tunnel, the vehicles in the UTLT are basical the small type cars, the vehicle flowrate and speed are low. When it comes to traffic jams and congestion, the pollutants continuous exhausted by vehicle waiting in the queue is relatively large, and directly discharged into the air environment surrounding the passenger. Therefore, it’s necessary to rationally design the ventilation system of underground tunnels, in order to solve air quality problem.This paper introduces the existing road tunnel ventilation and underground garage calculation methods and comparative examples to make the calculation, analyzes the differences between calculations and specifications related correction parameters.According to the analysis and comparison of the relevant air quality standards at home and abroad, determine the environmental control objectives of this type underground connecting tunnel, take the concentration standard for the main control target, and the difference is set for concentration limits, considering the waiting time of waiting staff in the underground tunnel, make sure the limit of CO concentration is bellow 30mg/m3, other regions in which both people and vehicles passing through are considered,the CO concentration allowed is to 86mg/m3.Analysis the particularity of the station of UTLT,drawing on the experience of the calculation method of tunnel ventilation,this paper proposes a new calculation method of ventilation and separate the underground tunnel according to the traffic speed,design and calculate the ventilation separatly,change the consideration of vehicle categories into the traffic amount in the corresponding traffic speed, the sum of the amount of each segment of ventilation are calculated to be an underground tunnel ventilation rate, then obtain the ventilation frequency of each segment and the sum of all the frequency.Take the underground traffic link tunnel of Haxi passenger transport station as the example, use the calculation method of ventilation above-mentioned to this example for design, it’s ventilation rate is about 10 times/h, and arrange the air port according to various districts’ ventilation by difference in the proportion, and then make a numerical simulation analysis to the ventilation system, and then analysis its concentration field, velocity field, temperature field, which showed that ventilation air volume calculated by the method described above can meet air quality requirements when traffic blocking.Finally, simulate the conventional arrangement of air ventilation method and the ventilation system when air ventilation frequency get changed, compare the ventilation effect with the effect used the method above-mentioned, and we get that differentiated arrangement can effectively remove indoor air pollutants and meet the air quality requirements of staff, and get that 10 times/h ventilation frequency can meet ventilation requirment from the method above-mentioned. Bigger ventilation certainly will make a better indoor environment,but the corresponding ventilation energy consumption will increase resulting in unnecessary waste,so 10 times/h of ventilation is both reasonable and economical,moreover this new algorithm for such type of projects ventilation calculation is instructive.