Study on Hydroaccumulation Patterns in V-Shaped Slope Tunnels of Subways During Floods

Abstract Under the broad consensus on reinforcing flood resilience in underground spaces, the hydraulic properties of metro tunnels have not been thoroughly examined. V-slope configurations are widely adopted as a standard feature in metro tunnel systems. This study aims to enhance the understanding of water propagation mechanisms in such tunnels to optimize the response of metro systems to upcoming floods. Through a combination of scaled physical model experiments and VOF numerical simulations, the research reveals key stages and patterns of water accumulation in V-shaped slope tunnels. The flood propagation process is divided into four stages: downhill flow on a single slope, uphill flow undergoing deceleration and accumulation, emergence of hydraulic jump, and wave reflection and oscillation. By investigating hydraulic jump characteristics and the evolution of submersion under varying conditions, the research highlights the local flow field discontinuity and identifies the incompatibility of existing hydraulic models with metro tunnel flooding prediction. It emphasizes the importance of considering detailed flood front movements and the surge of water depth for early flood warning in metro tunnels. The findings enhance predictive accuracy for inundation timing and dynamic flood progression.