An Experimental Study on the Stability of Filter Units on Rubble Mound Breakwater

S-type Filter Unit (FU) is a stone-filled filter net which is tied with a constraining rope from top to bottom from inside. Firstly, “Single-FU” experiments are performed using various FUs on a fixed rubble mound breakwater to study how the volume ratio of filter net to filling stones and the constraint degree of an S-type FU can affect its stability, and to investigate the optimum FU structure. Some S-type FUs could control their displacements effectively during the wave attack. Secondly, “Multiple-FU” experiment is conducted using the optimum FUs on rubble mound breakwater to assess the stability number of the FUs.