AbstractThis paper presents a stability estimation method for armor units to cover a rubble mound on the rear side of a caisson breakwater against tsunami overflow while taking into account the influence of the shape of the superstructures of the caisson. In this method, the required mass of the armor units is obtained from the impinging velocity onto the rear side mound. This is calculated by using the overflow depth. Accordingly, the influence of the shape of the superstructure is taken into account directly. This method also takes the influence of the slope angle into account properly by using the formula by Isbash. In addition, the influence of the impingement position of the overflow nappe and the influence of the thickness of the water jet are considered. The validity of this method is confirmed by comparing with the results of hydraulic model experiments conducted in a wide range of conditions.
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