Fire Smothering and Post-fire Ventilation Strategy for Cable Compartment in Urban Utility Tunnel

Abstract

To address fire safety of cable compartment in urban utility tunnel, provision of fire separation is necessary, and identifying a fire separation distance that is both safe and practical is thus of great importance. This paper studies the cable compartment fire occurring and development pattern, fire smothering, post-fire ventilation, and smoke exhausting under different fire separation distances by CFD numerical simulation. This paper proposes a general process for fire smothering in cable compartment of urban utility tunnel and comes up with a series of judging criteria for the best fire door opening time. The research discovers that under different fire separation distances, there is not big difference in maximum heat release rate (HRR) as well as the maximum temperature and smoke layer settling rate in the utility tunnel. After fire door is opened, the smoke exhaust time with an 800 m fire separation distance is obviously higher than any other fire separation distance. We believe that the present mainstream 200 m fire separation distance can be properly increased no matter from the perspective of fire spreading control or post-fire ventilation, for example, no excess of 500 m. The research results of this paper can provide theoretical basis for fire safety design and management of urban utility tunnels.