Study on emergency ventilation for train fire environment in metro interchange tunnel

Abstract

Metro interchange tunnels have been extensively constructed to meet the requirements of traffic organizations among travel lines. Fire safety issues remain a concern owing to the peculiar building structure and lack of special guidelines from current design standards and norms for ventilation. Focusing on this problem, and aiming to establish a safe evacuation environment, we carried out numerical simulations and full-scale experiment to investigate the efficiency of available co-work ventilation modes in eliminating smoke induced by train fire. The numerical model was constructed by Fire Dynamic Simulator 6.3.2, using the parameters of a real tunnel, ventilation systems containing tunnel ventilation fan (TVF), jet fan, ceiling duct, and the available co-work modes among these. The grid size and boundary conditions were verified through full-scale fire experiment and theoretical prediction by comparing the fire plume and ceiling jet flow temperature. The results demonstrate that, the semi-hybrid ventilation mode provides safe evacuation environment to the greatest extent, by utilizing the co-operation of TVFs, jet flow, and downstream ceiling extraction, compared to other modes. This mode effectively eliminated smoke and maintained the temperature, harmful gases, visibility and radiant heat flux at a safe level upstream of the fire. Furthermore, the optimized operation of the ceiling duct improved the smoke discharge efficiency as far as possible downstream of the middle carriage fire. An emergency response plan was eventually proposed for different fire scenarios, including equipment activation and passenger evacuation strategies, providing guidance for rapidly creating safe evacuation path in the interchange tunnel fire environment.