Field Applicability Analysis of Wave Transmission Coefficient Formulas for Submerged Structures (1. A System Composed of Detached Breakwaters and Submerged Breakwaters)

In this study, to evaluate the performance of submerged breakwaters installed in the Yeongrang district in Sokcho and the Bongpyeong district in Uljin, where large-scale coastal maintenance projects were implemented for the first time in Korea, continuous wave observations were conducted in front and behind the submerged breakwaters to calculate the wave transmission coefficient. Furthermore, the field applicability of the empirical formulas by Takayama et al. (1985) and Lee and Bae (2020), which extended the applicability of the former, was reviewed. Using the regression equations of the offshore data in the Yeongrang and Bongpyeong districts, the data were grouped according to wave period and wave height, and the observed values were compared with the results of the formulas for groups similar to the applicable ranges of the formulas. For the Yeongrang submerged breakwater, when the incident wave height exceeded 3 m, the wave transmission coefficient by the Takayama et al. (1985) formula was greater than the observed value, and the opposite was true when it was less than 3 m. For the Bongpyeong submerged breakwater, regardless of the incident wave height, the wave transmission coefficient from the Takayama et al. (1985) formula was consistently larger than the observed values, and the transmission coefficient increased as the wave height decreased. In the results including only data with a relative freeboard of 0.2 to 1.0 and a wave steepness of 0.01 to 0.06, the wave transmission coefficients from the Lee and Bae (2020) formula increased as the relative crest width decreased, exhibiting the same tendency as the hydraulic experiment results.