Numerical simulation of the water flow field on subway stairs and evaluation of people safety evacuation

ABSTRACT Stairs in subway stations are vulnerable to floods when rainstorm disasters occur in cities. The stairs, as a critical way for human evacuation, can affect the safe evacuation of people on flood-prone stairs. To evaluate the risk of people evacuating through different slopes and forms of stairs when floods invade subway stations, a numerical model for the water flow on stairs based on the volume of fluid model and the realizable k-ε model was established. The water flow patterns on stairs at the subway station entrance under different slope conditions and with/without rest platforms were simulated. The real-time water flow process on stairs at different inlet depths was obtained, and the escape control index F was used to evaluate the risk of people evacuating through stairs at different slopes and water depths. The results indicate that the presence of a rest platform can cause an increase in water velocity and depth on pedestrian stairs, and people should choose stairs without a rest platform for evacuation during the evacuation process. The research results hope to provide a reference for the people evacuation on stairs, and further improve the theory of safe evacuation of personnel on flood-prone stairs.