Large-scale experimental study of solitary wave loading on an embedded marine structure

This study presents large-scale flume experiments on solitary wave interactions with a square concrete structure embedded in sandy seabed. Unlike previous research on rigid foundations, the structure moved freely with six degrees of freedom, enabling realistic assessment of coupled wave-soil-structure dynamics. Breaking and non-breaking waves were examined. Instrumentation captured water surface elevations, flow velocities, wave pressures, pore pressures, and structural motion.Breaking waves generated maximum dynamic pressures of 9.5-12.5 times the local hydrostatic pressure, near the impact zone, producing displacements up to 16% of structure width and tilting of 2.5°. Impact pressure impulse contributed 19-24% of total impulse, with the remainder from quasi-static loading. Impact impulse correlated directly with displacement, indicating that momentum transfer likely governs dynamic response. Non-breaking waves produced lower pressures (1.3-1.7 times local hydrostatic) near still water level with negligible displacement. Pore pressure measurements revealed sharp drops coinciding with peak displacement under breaking waves, suggesting coupled soil-structure response.A simplified linear pressure distribution provided conservative force and moment estimates for the tested cases. However, broader testing with denser, higher-frequency sensors is needed to assess general applicability. The findings provide experimental benchmarks for numerical models and design methodologies for tsunami-resilient infrastructure, for coupled behavior of embedded foundations under extreme loading.