Abstract
In many ports, it has been reported that long-period waves cause trouble in cargo handling. As a countermeasure to this, a slightly submerged mound type long-period wave absorbing structure installed on the harbor side of the breakwater is proposed. Because the structure is to be situated behind the outer breakwater which faces the open sea, severe wave overtopping will inevitably be encountered. To realize such a structure, the armor units must have sufficient stability to overcome wave overtopping. However, the design method has not been established yet. Therefore stability tests on the armor units against wave overtopping from the sea side were conducted aiming at a design formula for armor units.
In this paper, it became clear that the deformation type of the long-period wave absorbing structure were different depending on the width of the structure. A prediction formula for the stability number for Tetrapods for each cross section condition used in the Hudson formula was proposed by modifying the existing empirical formula for the sea side Tetrapods on a horizontally composite breakwater. Its validity was confirmed. As a result, the required mass of Tetrapods for the proposed submerged structure can be calculated properly.
