Numerical simulation and disaster prevention strategies for flood intrusion process in subway stations

Subway stations are prone to serious consequences when occurring a flood disaster due to the isolation of subway stations from the ground. To assess the risk of personnel evacuation when floods invade subway stations and explore the safest evacuation time for people. A numerical simulation model for flood intrusion into a subway station was established in this study based on the Realizable k-ε turbulence and Volume of Fluid (VOF) model, which can be applied to simulate the water flow characteristics in subway stations. The subway station and tunnel model were constructed by taking a subway station in Zhengzhou Metro Line 5 as a research object. The impacts of tunnel floodgate opening/closing, different numbers of water inlets, and different inlet water depths on the flood invasion process were investigated. The flood invasion process, invasion time, and spread pattern of subway stations under various operating conditions were analyzed. Moreover, suggestions for human evacuation within the station were proposed. The results indicate that the closed tunnel floodgate causes an increase in water collection in the subway station. While opening the tunnel floodgate can efficiently relieve flood pressure in the subway station, it is critical to avoid floods pouring through the tunnel to the next station. The increase in water depth and water inlet number led to an increase in the water velocity intrusion into the subway station, resulting in a rapid increase in the water depth in the subway station, and pedestrians ought to evacuate the subway station as soon as possible. The research findings are intended to serve as a reference for the safe evacuation of people when floods invade subway stations.