Tsunami Over Composite Breakwater
Due to nappe non-aeration, a caisson breakwater subject to tsunami overflow experiences a greater sliding force than that predicted by the hydrostatic water level difference across it, indicating that design based on water levels alone may not be conservative. Via laboratory experiments, we develop a relation between cavity sub-pressure and nappe trajectory. Results suggest that the predicted sliding force exerted on a non-aerated caisson exceeds that exerted on an aerated caisson by about 10%. Furthermore, vigorous bubbling in the region below the non-aerated nappe may reduce the effective density of water facing the harbor-side wall of the caisson.