Breaking-wave loads on vertical walls suspended above mean sea level

Abstract

An experimental study of plunging-wave impacts on flat vertical walls suspended just above the still water level has been presented. Simultaneous pressure measurements are examined in conjunction with video records. From the results, impact conditions have been found to vary from one associated with a rising water mass and a progressively steeper wavefront during wave action to one with a well-developed plunging jet and significant air entrapment at impact. Pressure distributions and impact force time histories have also been presented to elucidate the spatial and temporal variations of the impact loads. For the plunging wave examined in the study, the highest horizontal force is found to be about two times higher than that on a surface-piercing wall over the zone above still water level. Dominant force oscillations immediately after the occurrence of peak force have also been found. Such oscillations, with amplitudes as high as nonimpact force levels, can have significant influence on the dynamics and stability of the structure.