Building underground water-sealed oil storage (UWSOS) caverns on islands poses a potential risk of seawater intrusion. As UWSOS is mostly constructed within rock masses, research on seawater intrusion through rock fractures holds important engineering value. This study combines single-fracture model tests with numerical simulations to investigate patterns of seawater intrusion in fractured rocks. Results show that, due to the density difference between seawater and freshwater, a saltwater wedge forms in coastal zones. Under tidal action, an upper saltwater plume forms in the intertidal zone, with its scale positively correlated with tidal range. After cavern excavation, the saltwater–freshwater transition zone widens, and seawater gradually intrudes from the cavern bottom. The upper saltwater plume evolves into a “saltwater tongue” during intrusion, with a growth rate ranging from 921.89% to 5691.52%, while the lower saltwater wedge moves landward by 37.86% to 82.65%. The saltwater tongue scale increases with tidal amplitude, but the lower wedge scale shrinks. With the horizontal water curtain installed, the saltwater wedge area decreases by 45.42% to 57.33%; in contrast, installing a vertical water curtain can effectively block seawater intrusion. These results provide an important experimental foundation for seawater intrusion research in island UWSOS caverns.
Li et al. (Mon,) studied this question.