Study on the reflection, transmission and wave energy dissipation characteristics of perforated hollow pile breakwaters

Abstract

To protect the mangrove forests along the coastal areas of Mekong Delta, the research group on coastal and river bank protection of Hydraulic Construction Institute has created perforated hollow pile breakwaters to reduce wave energy. Perforated hollow pile breakwaters (PHPB) were made by vertical perforated piles, they were installed in the ground and stabilized by the inner stones. This paper presents the results of study on reflection, wave energy dissipation and transmission characteristics of PHPB on physical model. The results show that the ratio of d/H varied from 0.7 to 0.93, the transmission coefficient (Kt) increased from 0.45 to 0.6 and the reflection coefficient (Kr) decreased from 0.55 to 0.47. At the d/H was 0.75, wave energy dissipation was maximum as 70% and Kt approximated 0.5 with Kr from 0.5 to 0.52. Thus, the authors suggested that the top elevation of structures should be chosen as 1.33 times of design sea water level when applying these structures for coastal protection projects.