Concrete Armor Blocks
Newly developed 100t wave dissipating blocks (Kd number 10) were used to extend the U-breakwater in N-port, designed as a sloping top breakwater covered with wave dissipating blocks (STBWB), The stability of the blocks was certificated by hydraulic experiment. However, breakage of caisson wall was caused by Typhoon 19 in 2014. After the disaster, we conducted hydraulic experiments and showed following results. 1) Upper wave dissipating blocks of the STBWB easily tremble and collide with the top of the caisson front wall. 2) Because the wave dissipating blocks were large, even trembling of the blocks caused a large collision force.