Vertical breakwater

    General introduction

The calculation rule computes the wave transmission of the significant wave over/through a "reef" breakwater, a conventional breakwater, a highly permeable breakwater, a vertical breakwater, an impermeable dam, vegetation or a row of piles. A "reef"-breakwater consists of a homogeneous pile of stones and has a low crest. A conventional breakwater is a layered structure (fine grading in the core overlain by several layers of coarse stone). In practice, a highly permeable breakwater will permit water only to pass though the structure and not over the top (no overtopping). A vertical breakwater consists of a caisson on a permeable foundation of stones. Transmission occurs as a result of overtopping, wave penetration under the caisson and movements of the caisson. Wave transmission through vegetation can be determined for rushes (scirpus sp./ scirpus lacustris) and for reeds, if the stalks extend above the surface of the water. With impermeable dams wave transmission occurs only via overtopping. Finally transmission through a row of piles depends on the distance between the piles, the size of the splits between the piles and the shape of the piles (round or square). In general:

In general:

     (equation 1)

Vertical breakwater

     (equation 2)

• hc  = height of the wall above the slack water line [m]

Reference:
[a] Goda, Y, 1985, Random seas and design of maritime structures, Univ. of Tokyo Press. P. 102