The airleakagerate oftunnelnumber oneTehran- Pardis tunnel with middle shaft pair byNumericalandanalyticalmethods

Generally the one middle shaft-longitudinal ventilation not used at sideway tunnels. Because، at the first half of thetunnel، direction of the moving of vehicles is same as the direction of ventilation and the piston effect will help ventilation، while at the second half، direction of moving vehicles is opposite to direction of ventilation، and the piston effect prevents ventilation. So، the second half of the tunnel is much polluted. Therefore the application of longitudinal ventilation with middle shaft in the sideway tunnels is implemented using twin middle shaft. So two devils are constructed in the center of the tunnel. The first one for pollutants exhaustion and the other for fresh air entrance. In this paper the possibility of using middle shaft in the ventilation system of Tehran-Pardis freeway number 1 tunnel is studied using analytical method. The tunnel’s air flow-rate is calculated using numerical method. So the 3- dimensional model of tunnel with 1550 length using FLUENT software is developed، and turbulence flow-rate is simulated using k-ε model. The results show that in some places، the local speed exceeds permitted speed. Therefore the proposed analytical method successively could be used for this purpose.