Study on Fire Dynamics of a Cable Compartment in an Underground Comprehensive Pipe Gallery

To investigate cable cabin fire characteristics, a 1∶1 full-scale model was built according to the actual situation of cable cabins in a comprehensive pipe gallery in a city to simulate cable cabin fires. Through the ventilation mode of the cable compartment in case of fire, the influence of different ventilation rates on the cable compartment fire under the conditions of closing the cable compartment ventilation system, natural air intake + mechanical exhaust ventilation mode, and mechanical air intake + mechanical exhaust ventilation mode was explored. The research demonstrates that the progression of fire within the cable compartment situated in the comprehensive pipe gallery follows a five-stage sequence: smoldering, incipient, developing, violent, and attenuation. Without a fire extinguishing system in place, the oxygen within the cable compartment can sustain the fire for approximately 450 s. Elevated CO2 concentrations are detected at the center, top, and ends of the cable bin, while the lowest CO2 concentration is observed at the bottom of the cable bin. Initiating the natural air intake with a mechanical exhaust ventilation system and maintaining a low ventilation rate of approximately 2 times/h is optimal for fire development and temperature dispersion. Under the mechanical air intake with mechanical exhaust ventilation mode, high ventilation rates of 8 times/h and 10 times/h significantly exacerbate the fire. The findings of this study can offer valuable guidance for the development of fire protection systems for cable cabins.