| As a kind of fast, environmental, safe and high transport capacity transportation means in urban areas, metro industry has rapidly developed and been widely applied in our country for the past few years. Due to the whole structure of the metro is underground, less exits and the staff is complex, dense, the result of fire is unimaginable. Therefore many experts and scholars made numerical simulation, and obtained many achievements.However, in the analysis process of fire numerical simulation in metro was found the tunnel entrence bountory conditions exert a significant influence. In this paper, firstly, the anthor set up a model of metro with a long tunnel, according to the numerical simulation results, the fire smoke cannot spread out of the400-metre-long tunnels in1200s. Then set up two kinds of typical fire scenario through different metro station (island metro station and side metro station) to reduce the width of the tunnel entrance setting nine kinds of equivalent model of boundary condition for each fire scenario. Finally by comparison with the various parameters such as temperature, visibility etc of numerical simulation results of equivalent model and complete model, using relevant mathematical interpolation to data fitting, and intergrated many factors eventually got the equivalent width coefficient ε of tunnel entrance of island metro station0.4, the equivalent width coefficient ε of tunnel entrance of side metro station0.7.The equivalent width coefficient of tunnel entrance of metro station of significance is to simplify the model boundary conditions, to reduce the comoutational mesh volume and numerical calculation time, while still relatively accurate simulation results. The equivalent width coefficient ε of tunnel entrance can be applied widely in the fields of the fire risk assessment and performance-based fire protection design of metro station and tunnel, helping to save the numerical calculation time in the process of the design proposal optimizing. |
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