Numerical Simulation On The Flooding In Subway Station And Discussion On Its Flood Prevention Measures

Underground facilities, such as basement, mass Transit Mall, subway, underground parking are particularly vulnerable to flooding. Because of large-scale development and utilization of underground space and frequent heavy rainfall events, there are already many cities suffered underground flooding and extensive damage to property and life. Thence, research on flooding process in confined underground space during the period of extremely heavy rainfall and the proposals for flooding prevention inunderground space were proposed for the normal operation of urban rapid rail transport and the safety of life and property in underground space.A numerical model of subway station has been established to simulate the whole process of flooding movement in subway station dynamically. The flooding prevention measures for subway station have been proposed. Specific research contents as follow:Firstly, the mathematical expression of safe evacuation time from the underground space through staircase has been deduced. The correlation between rainfall probability and the safe evacuation time has been established which can be used to judge the possibility of ground waterlogging intrusion into underground space under certain rainfall intensity.Secondly, based on the gas-liquid two-phase flow theory, a numerical simulation model of underground space has been established by the three-dimensional standard k-e turbulence model coupled VOF method. Then, the VOF model and the parameters in the model were calibrated based on the comparisons between the modelling results and the experimental date obtained by Oertel. Takeing the subway station under construction in Hangzhou as a typical example, a numerical model of subway station was established by simplifying the interior space of station. Under several typical working conditions, flooding movements in underground space were simulated dynamically. The temporal processes of the water level of feature points were obtained, as well as the dangerous airflow field and water flow field at different time and the safe evacuation routes. Finally, flooding prevention measures for subway station, such as flood gate, enhanced drainage, were suggested. The flooding process in subway station under those flooding prevention measures were simulated by modifying the boundary conditions of numerical model and their effectiveness against flood were evaluated.