Comparison of Wave Pressure on the Front Wall of the Caisson Breakwater without and with the Cap of Wave Chamber

Abstract

This study experimentally investigated the change in distribution of wave pressure on the front wall according to the existence of the cap of the wave chamber of the perforated caisson breakwater. In order to obtain reliable experimental data, the measurement of wave pressure for the non-porous caisson corresponding to zero porosity was first carried out and the results were compared with the well-known pressure formula suggested by Goda(1974). The analysis showed that the measured pressure distribution fairly well agreed with the Goda formula, which confirmed the accurate measurement of wave pressure in the present experiment. Then, the experiment was performed for the perforated caisson by varying the front wall porosity as well as the existence of the wave chamber cap. The wave pressure distribution along the porous front wall showed some noticeable difference according to the porosity when there was cap of the wave chamber. In addition, the magnitudes of the total wave force estimated by integration of the measured wave pressure showed marked discrepancy for the case without and with the cap of the wave chamber. In the latter case, in particular, significantly larger wave forces compared to the value based on Takahashi’s formula (Takahashi and Shimosako, 1994) were obtained influenced by the gentle air compression and subsequent burst phenomenon occurred in the wave chamber. Further analysis is required for geneta, the measurement of wave pressure for the non-porous caisson corresponding to zero porosity was first carried out and the results were compared with the well-known pressure formula suggested by Goda(1974). The analysis showed that the measured pressure distribution fairly well agreed with the Goda formula, which confirmed the accurate measurement of wave pressure in the present experiment. Then, the experiment was performed for the perforated caisson by varying the front wall porosity as well as the existence of the wave chamber cap. The wave pressure distribution along the porous front wall showed some noticeable difference according to the porosity when there was cap of the wave chamber. In addition, the magnitudes of the total wave force estimated by integration of the measured wave pressure showed marked discrepancy for the case without and with the cap of the wave chamber. In the latter case, in particular, significantly larger wave forces compared to the value based on Takahashi’s formula (Takahashi and Shimosako, 1994) were obtained influenced by the gentle air compression and subsequent burst phenomenon occurred in the wave chamber. Further analysis is required for gene