A DESIGN SHORT-CRESTED WAVE FORCE MODEL FOR VERTICAL DEEP-WATER BREAKWATERS

S.Y. Tzang, S.R. Liaw

Abstract


Fenton's short-crested wave force approximations were modified for designing a vertical breakwater in deep water regions. The theoretical water surface profiles and depth-distributions of hydrodynamic pressure in front of a vertical breakwater were first evaluated with field wave conditions of height HD=lOm and period T=9.6s at depths d from 20m to 40m. The calculations immediately illustrated characteristics of residual pressures at wave crest and exponentially decreasing profiles under design water level. As d increased, wave crest height decreased as well and the crest pressure deviations became negligible while overestimated pressure force by assuming linear under-water pressure distributions became more significant. Through appropriate modifications, a design wave force model were proposed and compared with Goda's design formulae for standing waves. Results clearly displayed that 45° incident short-crested waves could induce greater total wave forces on a vertical breakwater than those by Goda's formulae at the same depth. Differences became greater at </=40m by about 12% ~ 17% for 7M0s and 17% ~ 29% for T=18s based on Fenton's 2nd and 3rd-order approximations.

Keywords


breakwater; deep water; wave force; force model

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