Experimental study on the wave reflection of partially perforated wall caissons with single and double chambers

Laboratory benchmark tests for wave reflection through partially perforated wall caisson structures with single and double chambers were conducted in a wave flume. Reflection coefficients were calculated and the configuration of the structure had a varying chamber width, number of slits, and porosity of the vertical wall including front and middle wall. In the single chambered model case, reflection coefficients were smaller when the porosity of the front wall was smaller within the porosity range of this study (20-60%) while the effect of the number of slits was small. In the double chambered model case, when the middle wall porosity was smaller than the front wall porosity, the reflection coefficients dropped significantly compared to the opposite cases. Especially, the reflection coefficients were reduced drastically when the middle wall porosity was 20%. This study shows that, if the total chamber widths are same, a double chambered model when the middle wall porosity is lower than the front wall show a better performance in terms of reducing wave reflection than a single chambered model does. However, the reflection coefficient reduction in double chamber cases was not improved when the front wall porosity was lower than the middle wall porosity.