Abstract: To investigate the impact of single-sided and double-sided mechanical smoke exhaust on fire smoke control and spread at the upper lane in a double-deck tunnel, FDS was used to conduct a comparative study on the smoke control effectiveness in a typical double-deck tunnel under different exhaust control modes.Based on illustrating the rationality of the model, the smoke spreading distance, gas mass flow rate and temperature distribution at the smoke exhaust vent were comparatively analyzed under different smoke exhaust fan opening modes. The study showed that the gas mass flow rate distribution at the smoke exhaust outlet shows different patterns when the exhaust fan is activated on the single-side or double-side. When the smoke exhaust fans on both sides of the tunnel are turned on, the smoke spread range is the smallest, which is 47.8%~88.1% of the exhaust fan on the downstream side of the tunnel are opened under the same smoke exhaust volume. And the average temperature at each smoke exhaust outlet is lower, which comprehensively reflects that turning on the smoke exhaust fans on both sides of the tunnel has a better smoke control effect. In addition, the variation of the tunnel smoke spread range with the fire source position under the single-side and double-side smoke exhaust modes was also discussed.

Key words: double-deck shield tunnel, mechanical smoke exhaust, smoke spreading distance, exhaust volume of smoke vent, temperature field