To investigate the reflection, transmission characteristics and energy dissipation of porous-piled structures, a series of physical experiments were conducted in this research. The results indicated that the reflection coefficient of double-row structure while 2S/L (S is the structure gap spacing, L is an incident wave length) = 1 or 2 has a peak, also the peak value is larger when porous coefficient is smaller. This phenomenon is quite similar to the Bragg effect. Besides, the reflection coefficient and energy dissipation decreasing (transmission coefficient increasing) while porous coefficient of the structure increasing.
All structures in the coastal zone have one thing in common: they must be able to withstand the forces caused by wave attack. Generally, breakwater can be divided into many types, in which the rubble-mound breakwaters and the monolithic breakwaters are the most important twos. Next to that, there are a few special types for some special purposes because of the complex coast bathymetry or environmental protection consideration. Recently, a severe damage to a coastal structure due to a storm surge happened in Hua-Lien coast, where is a steep slope foreshore in Taiwan east coast. Although the investigation into the damage is still go on and many protection approaches are concerned. However, the most important of this problem is that the steepness of sea bottom in front of the sea defence makes the engineering very difficult. In order to overcome this kind of difficulty, the special types of breakwaters would be concerned. In the following, we will concern some special type of breakwaters: Firstly, submerged breakwaters are mainly built of rubble stones. They reduce the wave energy passing to the onshore zone while causing breaking of large waves only. Early research considered the dynamic interaction between the wave and the breakwater.
