A series of hydraulic model experiments was systematically and carefully carried out to estimate the stability of various types of armor units for a harbor-side rubble mound of a composite breakwater against a water jet caused by an impinging bore-like tsunami. Armor stones of weight 1 ton were seen to be easily removed by the tsunami flow. Flat type concrete blocks with well-arranged holes showed high stability. In the case of using wave-dissipating blocks, the total stability of the armor layer was enhanced by placing heavier blocks along the toe of the slope. Numerical analysis was also carried out to investigate the effect of the shape of the blocks. The computed time series of water level and the behavior of the impinging jet agreed well with the experimental ones. The computational result of hydrodynamic forces acting on armor blocks revealed that the uplift forces were largely decreased by the holes in the blocks.

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A series of hydraulic model experiments was performed to clarify the effect of Wave-Dissipating works on wave force reduction of tsunami with soliton fission. First, under the conditions of a wide range of water depth and wave period, the process of tsunami deformation was examined to understand the characteristics of tsunami profiles at the soliton fission including the relation between degree of dispersion and travel distance. Then, the relationship between the pressure of the soliton waves acting on the vertical wall and the degree of dispersion was studied. Finally, the effect of wave-dissipating works on wave force reduction of tsunami was investigated by comparing the wave pressures on a caisson with and without the works under the condition of breaking and non-breaking soliton wave.

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