Abstract
In many ports, it has been reported that long-period waves cause trouble in cargo handling. As a countermeasure to this, a wave absorbing mound installed on the harbor-side of the breakwater is proposed. The crown height of the mound is almost equal to that of the caisson. However, because of the low wave absorbing performance of such conventional structures, the required width to absorb the long-period waves becomes more than 30m. It is important therefore to reduce the size of the structure to apply to various site conditions. In this study, a submerged mound type long-period wave absorbing structure is proposed. A series of hydraulic model experiments was systematically and carefully carried out to evaluate the wave absorbing performance of the proposed structure.
Throughout this study, it became clear that submerged structures display a higher wave absorbing performance compared with those of conventional structures. In particular, the wave absorbing performance of a two-layer covering of concrete armor blocks is significant. For example, under conditions where the water depth is 10m and the wave period is 60s, a 16m width submerged structure is equivalent to a 30m width conventional structure from the standpoints of wave absorbing performance. As a result, it can be expected that the proposed submerged structure would contribute to cost reduction. Such mound structures are particularly applicable to middle- and small-sized harbors.
