Numerical Analysis about the ShangJie Highway of Tunnel Fire Based on FDS
|Course||Detection Technology and Automation|
|Keywords||tunnel fire FDS numerical analysis temperature CO concentration visibility|
The highway tunnel fire has always been followed with interest and studied earnestly by great many scholars at home and abroad, for it is one of the major disasters affecting the safety of highway operation. Currently, the research about tunnel fire mainly focuses on the following areas:the model test of temperature distribution, the Three-Dimensional Numerical Simulation of tunnel fire, the critical of wind speed, the ventilation plan under the way of semi-transverse ventilation system, the damage in the lining of the fire, the problem of how to evacuate people safely in case of tunnel fire. However, the study on the CO concentration, the distribution of visibility, the occurrence and development of temperature distribution based on the conditions of how to evacuate people and vehicles safely in tunnel fire is very little due to the following limitations:the difficulties of monitoring the CO concentration and the visibility distribution, the defects of fire simulation software in the simulation of visibility.This paper relies on the project of ShangJie highway tunnel group to study on the tunnel fire.Combined with the characteristics of the whole project, we select the LuJiashan 1st tunnel as our major subject for it is the longest and most dangerous section of the highway.Firstly, according to the FDS model, the fires of different size under natural ventilation and mechanical ventilation in LuJiashan 1st tunnel were divided into 6 conditions. We established the simulation models and conducted numerical simulations for every condition. According to the statistics, it is feasible to use FDS model to conduct numerical analysis about the tunnel fires, which can well investigate the rule of the occurrence and development of the temperature and smoke.Secondly, the diffusion of temperature field in the 6 conditions was researched. We studied on the temperature variation with the development of time, the vertical distribution of temperature, the transverse distribution of temperature in the height of person and the spread of the temperature field. The research result indicated that using the mechanical ventilation at the speed of 3m/s, we can effectively control the spread of high temperature flue gas to reduce the temperature inside the tunnel and create an advantageous environment for the safe evacuation of people and vehicles.Finally, we researched on the smoke field diffusion of the tunnel fire in the 6 conditions. Because the CO concentration and visibility is the main factor which influence the evacuation of people and vehicles in the tunnel fire, we mainly studied on the vertical and horizontal distribution of CO concentration and visibility. The studies shown that when there is a tunnel fire, either in the case of natural ventilation or mechanical ventilation, considering the CO concentration and visibility, people and vehicles in the lower reaches of the fire source should evacuate along the center line of the tunnel.