Design Wave Force on Perforated Caisson Breakwaters with Wave Dissipating Blocks

Abstract

A perforated caisson breakwater with wave-dissipating blocks, which has passage holes in the caissons, was developed for the purpose of maintaining a superior water quality environment in the landward area of a port. This structure allows permeability of tides and permanent currents, and uses wave energy to introduce seaward water into the landward water area of the port.In order to examine the wave force characteristics on perforated caisson breakwaters with wavedissipating blocks, a, two-dimensional hydraulic model experiment was conducted. Based on the results, a method of structurally resistive design against wave action was proposed. This method is an expansion the general design method for breakwaters covered with wave-dissipating blocks, upon which the Goda's method had been applied. It is believed that general horizontal wave forces and uplift pressure, which were obtained by introducing the wave pressure reduction coefficient to the Goda's method, are applied to the front and bottom surfaces of the caisson. The horizontal wave force, however, was not applied because there were no pressure receiving surfaces at the openings of the passage holes, but inner-hole uplift pressure was applied onto the upper surface in the passage holes. Appropriateness of this method was confirmed in sliding tests.Keyword ; sea water exchange, structurally resistive design against wave action, hydraulic model experiment