WAVE OVERTOPPING CHARACTERISTICS OF BLOCK MASONRY SEAWALL AND A STUDY ON EFFECT OF SHORE SLOPE

In a design of seawalls, it is important to keep wave overtopping discharge below an allowable value, whereas it is desirable to keep a crown height of seawall as low as possible from viewpoint of water affinity and landscape.When there is a limit to expansion of seawalls to front sea area, vertical block masonry seawalls are sometime employed. Although authors compared the overtopping characteristics of two types of block masonry seawalls with those of vertical seawall, the shore slope is limited in 1/30. This study carries out a series of hydraulic model experiment with 1/10 shore slope and the overtopping characteristics were compared with the results of different beach slope. Results of experiment show the reduction of wave overtopping was improved when a lid was attached to the top of the seawall with the diamond-shaped opening. As the shore slope gradient increased, the reflection rate in front of the seawall decreased and the overtopping discharge increased. We proposed empirical formulas and figures which enable to estimate overtopping and wave runup for block masonry seawall with different slopes.