Abstract:Taking a metro depot in a megacity in eastern China as the research object on the core goal of flood control safety risk assessment, its spatial layout, hydrological environment and facility characteristics are systematically analyzed, and a multi-dimensional flood control risk assessment model integrating topography, drainage system and flood control facilities is established. Based on the model, the risk identification and quantitative evaluation are carried out for key flood control nodes including the main depot area, access tunnel portals, drainage pumping stations and external drainage passages. Two major potential hazards are identified, such as insufficient regional drainage capacity caused by backflow of the eastern municipal pipe network, and defects in water retaining facilities due to the hump elevation at entrances and exits being 0.07~0.20 m lower than the main road pavement. The results show that under the rainfall condition with a 4-year return period, the designed drainage capacity of the depot rainwater pumping station meets the code requirements, but the eastern external drainage channel is prone to failure due to the lag of municipal pipe network drainage. The drainage ditch outside the enclosure wall can effectively divert the surrounding catchment. Accordingly, a hierarchical prevention and control system is constructed. In terms of engineering design, measures such as adding anti-backflow valves and expanding drainage channels are proposed for renovation. In terms of management, seven dynamic prevention and control measures are formulated, including pre-flood season dredging and sandbag blocking during heavy rain periods, which can provide theoretical basis and engineering reference for enhancing the flood control resilience of rail transit.
