Study On Highway Tunnel Fire Impacts On The Cross Passage Interval

Zhejiang Kuocangshan King-size Highway tunnel is dual one-way traffic one, and longitudinal ventilation is adopted within 1,500 meters near the entrance and the exit, and the flue is installed and semi-transverse ventilation is adopted in the central tunnel. In case of fire in tunnel, especially the fire occurred in the central tunnel, the scene of the accident are far from both the entrance and the exit of the tunnel, it is difficult for personnel to evacuate from the tunnel in a short period of time. Therefore, it is particularly important to set a cross passage for refuge establishment to evacuate with some distance between both one-way traffic tunnels, and it is extremely important role for personnel safe evacuation to set its reasonable distance.The cross passage interval of some highway tunnels internal and external is investigated and the database is established in this paper.By statistical analyzing it, and taking into account the state of the recommended values on the cross passage interval, the interval range of Kuocangshan King-size Highway tunnel is approximately identified.The cross passage interval is something to the two main factors that is safety and economy in fire pattern, and the safety is influenced on both tunnel fire characteristic and personnel evacuation characteristics. A three-dimensional mathematical model in tunnel fire is established and the fire is simulated. VHS model as a fire burning model, and focusing on the fire source development process, smoke movement was acquired by the model consisted of continuity equation, momentum equation, energy equation and species equations. Finite volume method was used to discretize the govering equations and the SIMPLE algorithm was employed to solve the discretized equations. A critical velocity for the heat release rate of 30MW is calculated and temperature and smoke (CO) concentration is attained under different ventilation conditions in different fire scene; Based on personnel evacuation with time, temperature and concentration for the three escape routes that personnel may select were calculated and compared, and the best evacuation route was identified under the different conditions. Personnel behavior and evacuation characteristics in the fire were analyzed as the basis of the evaluation criteria for personnel safe evacuation. Combined tunnel fire characteristics and based on the most disadvantaged evacuation routes, the fire danger time and personnel necessary evacuation time were calculated and compared, and the define of the Critical Time of Personnel Safe Evacuation and the Critical Distance of Personnel Safe Evacuation were put forward. According to the calculated results, while taking into account its security and economy, the average cross passage interval of Kuocangshan highway tunnel is obtained. The method and the conclusion provide the theoretical basis for the reasonable cross passage interval, emergency evacuation program and tunnel fire safety design for king-size highway tunnels.