| Popis: |
The hydrodynamic performance of vertical and sloped plane, rectangular serrated, and triangular serrated seawalls were investigated experimentally in terms of wave reflection coefficient, kr, relative wave run-up, Rup/Hi, and relative wave run-down, Rdown/Hi, using physical model studies. Regular waves of wide rang of heights, and periods were used. Tests were carried out for different inclinations of seawall (i.e. ), relative dissipater blocks spacing (s/w =1.0, 2.0, 3.0), and a constant water depth of 0.4 m. It was observed that the rectangular serrated seawall was superior to the triangular serrated and plane seawall in reducing the hydrodynamic parameters mentioned above. As well it was found that the relative spacing of dissipater blocks, s/w, wave steepness, Hi/Li, and the relative water depth, d/Li were better influencing parameters compared to the surf similarity parameter (Iribarren N0), in predicting the wave hydrodynamic parameters. Both rectangular and triangular serrated seawalls gives a good results for all hydrodynamic parameters when, s/w=2.0 compared to s/w equal to1.0 and 3.0. A total performance evaluation was done in terms of a single parameter called hydrodynamic performance parameter, and it was found that for s/w=2.0, both rectangular and triangular serrations reduces this parameter by about 37% and 28% respectively compared with the plane seawall. The worst results for performance parameter were observed when , while the optimum values occur when, s/w equal to (2.21-2.27), and (2.34-2.41) for the rectangular and triangular serrated seawalls respectively. Simple predictive equations were developed for estimating the wave reflection coefficients, relative run-up, and relative run-down by using non-linear regression analysis by SPSS.16 (SPSS Inc, 2006) software. |
