Evaluation of Leakage Due to Submerged Floating Tunnel Crack and Its Propagation Characteristics

The submerged floating tunnel (SFT) is a type that allows tunnel floating owing to the water buoyancy. SFTs are often subjected to high-water pressure and environmental loads, such as waves and currents, which differ from those experienced by typical underground tunnels. In these SFTs, a sudden, large water leak can occur owing to collisions with external objects (such as ships), mooring lines for anchoring, and structural fatigue failure. To address these unexpected situations, it is necessary to develop a disaster prevention system for leakages. However, tunnel leaks and their propagation characteristics within tunnels have not been studied in depth. In this study, numerical simulations were performed using the commercial software program FLOW-3D to evaluate the characteristics of the water flowing through the tunnel owing to local damages to tunnel segments. In the simulations, a representative cross-section of the SFT was modeled, and the water propagation characteristics with respect to the crack size and water depth were evaluated. The results confirmed that the crack size and water depth significantly affected the propagation characteristics of the leaks. The results of this study are expected to be used as useful data for the design of disaster prevention systems for leaks in SFT.