BREAKING-WAVE LOADS ON VERTICAL WALLS SUSPENDED ABOVE MEAN SEA-LEVEL

An experimental study of plunging-wave impacts on flat vertical walls suspended just above the still water level has been presented. Simulta neous pressure measurements are examined in conjunction with video rec ords. From the results, impact conditions have been found to vary from one associated with a rising water mass and a progressively steeper w avefront during wave action to one with a well-developed plunging jet and significant air entrapment at impact. Pressure distributions and i mpact force time histories have also been presented to elucidate the s patial and temporal variations of the impact loads. For the plunging w ave 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 oscillat ions, with amplitudes as high as nonimpact force levels, can have sign ificant influence on the dynamics and stability of the structure.