Numerical Simulation Research on the Fire in Cable Cabin of Utility Tunnel with Different Channel Widths

The causes of fire in the cable cabin of the urban utility tunnel are mainly affected by its geographical location, cable layout model, environmental characteristics and other factors. Aiming at the common two-sided cable cabin structure in domestic utility tunnel construction, a full-scale model was established by the Fire Dynamics Simulator (FDS) to study the fire characteristics and temperature distribution in the two-sided cable cabin of a utility tunnel with different channel width and fire power. Five different channel widths (from 1.0 to 2.0 m) were set up under different fire power in a 200-m fire compartment. The results present that there are two types of Flame propagation pattern in the two-sided cable cabin: unilateral flame spreading upward and radiation igniting the opposite cable. The transverse temperature distribution of the cable cabin in the utility tunnel gradually decreases with the increase of the channel width. When the channel width reaches 1.6 m, the continuous increase of the channel distance has little effect on the transverse temperature distribution. The longitudinal temperature distribution of the cable cabin in the utility tunnel gradually approaches with the increase of the fire power, and showed a trend of first rising and then decreasing with the increase of the channel width. When the width of the utility tunnel is 1.4 m, the longitudinal temperature distribution is the highest. The results can provide a basis for the fire prevention and structural design of the cable cabin in the urban utility tunnel.