In recent years, the construction of offshore tunnels in China has made apparent achievements in termsof both quantity and capacity. Subaqueous tunnel fire is the most severe type of accident endangeringsubaqueous tunnel due to its heavy smoke, high temperature as well as difficult smoke extraction andevacuation. This article studies the safety evaluation of ventilation and smoke exhaust system for asubsea tunnel project in China which is under planning and engineering design. By studying thecharacteristics of subaqueous tunnels, the adoption of suction type semi-transverse ventilation methodfor the linkage portion of the subaqueous tunnel and longitudinal ventilation method for the portion ofsubaqueous tunnel itself are proposed, including the design of the ventilating shaft, vent duct and ventopening. A theoretical model for verifying smoke exhaust capacity is proposed, by which the flow ratesof the fans are then established. Based on the design parameter of the smoke exhaust system, anumerical simulation of a typical fire in the linkage portion of the subaqueous tunnel by LES method isperformed. Through the numerical results, the airflow organization, smoke spread process, temperature,visibility and CO concentration in the linkage tunnel are calculated and analyzed, then the feasibility ofthe smoke exhaust system designed for the linkage portion is further discussed.
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