In order to minimize the construction cost of the breakwater for a comparatively deep sea area, such as 20 to 30m depths, a new type of curtain walled breakwater is proposed. It is a gravity-type curtain-walled breakwater mounted on the concrete-made mound with wide footings. Super structures and curtain walls are supported by steel piles fixed on the concrete mound.
Wave transmission and reflection characteristics of the new breakwater are examined experimentally by changing configurations of super structures and draft depths of curtain walls. Numerical computations by the damping wave theory are also conducted to find out the optimal section of the breakwater.
Wave forces on the new breakwater with an optimal section were also examined experimentally and theoretically. Stability test of the breakwater against waves was also carried out.
A curtain-walled breakwater, which is often called as a vertical barrier, is usually supported by slightly inclined steel or concrete piles. It has been used for comparatively mild sea areas where a wave height is not so high (typically less than 3m) and a wave length is not so long (typically corresponding wave period is less than 4 or 5s). The concrete curtain wall covers only the upper part of the water depth to effectively intercept wave motions near the water surface. It has become known that transmitted waves through a curtain-walled breakwater are comparatively low especially for short waves (Wiegel 1960, Kriebel et al 1996, Krievel 1999).
A curtain-walled breakwater has been mainly adopted for the harbor with a soft ground under the sea and comparatively mild wave climate. However, for the harbor with a deep depth, say 20m or 30m, and with comparatively mild wave climate, it is sometimes recommended to construct a curtain-walled type breakwater for effective reductions of incoming waves.
