STABILITY EXPERIMENT ON HOLLOW CUBE BLOCK AGAINST IRREGULAR WAVES IN ARTIFICIAL REEF

The hollow cube block with permeable frames in all directions does not prevent along shore currents and has an advantage for reducing wave setup compared with flat type armor blocks. This study clarified the stability of the hollow cube blocks against irregular waves in artificial reef by conducting hydraulic model experiment. In addition, the damage pattern was examined and notes on design and construction were presented. Results of experiment showed that the stability of the hollow cube blocks decrease as the wave period becomes long. In the case of the same wave period, it was found that the stability increases by widening the setback width Lm of the hollow cube blocks. Furthermore, the damage expands easily when waves with specific period and wave height act in case of enlarging Lm. Therefore, it is necessary to set appropriate Lm by paying attention to local wave conditions. Since the hollow cube blocks on the shore side end may overturn, the installation of the armor blocks at the shore side edge of hollow cube blocks on the rubble mound is effective as overturning countermeasures.