# Study on Fire Smoke Distribution and Safety Evacuation of Subway Station Based on BIM
## 1 Introduction  
The increase in passenger flow has brought many difficulties to subway operation. In particular, it brings great challenges to the disaster prevention and evacuation of subway stations. The characteristics of subway stations, such as dense flow of people, numerous equipment, closed, low, narrow and long space, are not conducive to disaster prevention. Once a fire occurs, it will be difficult to fight and rescue, with great social influence and unpredictable losses. It is very important to evacuate people safely in case of a fire in a subway station. How to arrange the public area of a subway station reasonably in a certain space is particularly important to further improve the passing ability of vertical traffic in the evacuation process of subway stations. The application of BIM technology first started in the construction industry and gradually expanded to other fields. BIM technology has high precision and credibility when building models, as it can provide simulation scenes for evacuation simulation and fire simulation and display the internal structure of buildings in three dimensions, as well as other advantages. Domestic and foreign scholars take BIM technology as the basis, combine it with numerical simulation and algorithms, and conduct detailed and in-depth research on fire safety evacuation and rescue. [PERSON] et al. [1] proposed the idea of personnel evacuation simulation on the basis of a BIM model, providing a new ideafor the combination of a BIM model and an evacuation simulation. The BIM model was used to provide real scenes for personnel evacuation and fire combustion, and the process of fire combustion and evacuation can be observed intuitively. The simulation results were closer to the real situation. [PERSON] et al. [2] established a relevant model for passengers' selection of stairs and escalators during evacuation and verified the prediction accuracy of the model. [PERSON] [3] combined BIM technology with a fire safety evacuation simulation of subway stations based on the shortcomings of traditional simulation methods in evacuation research, and verified that BIM technology was helpful to improve the accuracy of evacuation results and display the evacuation simulation process more intuitively. [PERSON] et al. [4] used the Revit software to build a subway model and imported it into PyroSim, and used this model to simulate the CO concentration and temperature at various locations in subway stations. [PERSON] et al. [5] and [PERSON] et al. [6] studied the differences in passenger evacuation behaviors and further determined the relevant factors affecting emergency evacuation. [PERSON] [7] and [PERSON] et al. [8] studied the relationship between personnel density and walking speed, the maximum capacity of each traffic structure and the evacuation characteristics of personnel in different time periods. [PERSON] [9] and [PERSON] et al. [10], through studying the fire evacuation situation of subway stations, proposed to increase the width of exits, open all gates and lattice doors as well as other methods to reduce the evacuation time. Regarding the spatial optimization design method of public areas in subway stations, [PERSON] [11], [PERSON] et al. [12] and [PERSON] [13] expounded the behavior characteristics of passengers in subway stations with examples, and discussed the influence of passengers' behavior on the setting of stairs and escalators in stations. [PERSON] [14] carried out a simulation analysis in combination with three layout schemes of stairs and escalators in public areas of 12 m single-column island platform. It is determined that the form of stair and escalator + double escalators + vertical ladder + double escalators + stair and escalator is more conducive to passenger evacuation. [PERSON] [15] combined the built BIM model with fire simulation software and personnel safety evacuation software, analyzed the development process of fire and personnel evacuation process and proposed relevant feasible measures to further accelerate personnel safety evacuation.