월파저감 호안구조물에 대한 성능평가 및 월파량 예측식 적용성 검토

다국어 초록 (Multilingual Abstract)

In this study, the mean wave overtopping characteristics of vertical-type and return-type crown walls installed on rubble-mound breakwaters armored with tetrapods were experimentally investigated, and the applicability and limitations of the mean overtopping formula proposed in EurOtop (2018) were evaluated. The original reduction coefficient in the EurOtop formulation was derived primarily from experiments with irregularly placed tetrapods; however, the present results demonstrate that under the double-layered, regularly placed conditions commonly adopted in Korea, the formula consistently underestimates mean overtopping rates. To improve the predictive accuracy of mean overtopping, four types of reduction coefficients—fixed, exponential, inverse, and linear—were proposed and optimized using the Levenberg–Marquardt (LM) algorithm. Comparative analyses of both vertical and return-type crown walls revealed that the inverse-type reduction coefficient performed best overall. The inverse-type coefficient produced the smallest error values in terms of RMSE, SI, and SD, while achieving a Nash–Sutcliffe Efficiency (NSE) exceeding 0.93, indicating substantially higher predictive reliability compared with the other coefficient forms. Scatter-plot analyses of predicted and measured overtopping rates also showed that the inverse-type model yielded the least under- and overestimation across both low- and high-overtopping conditions. Similar trends were observed for the return-type crown wall, implying that a single reduction coefficient in the existing EurOtop formula is insufficient to capture the influence of crown-wall geometry on overtopping behavior. The inverse-type reduction coefficient proposed in this study effectively reflects the nonlinear dependence of overtopping reduction on wave steepness and structural configuration, offering a more realistic and reliable approach for evaluating overtopping discharge in Korean coastal and port structures. The findings of this study are expected to supplement the limitations of the existing EurOtop formulation and serve as essential reference data for establishing overtopping prediction frameworks tailored to domestic coastal conditions.

목차 (Table of Contents)

• List of Tables· iii
• List of Figures iv
• ABSTRACT v
• 1. 서 론· 1
• 1.1 연구 배경 1
• 1.2 월파량 예측에 관한 기존 연구 동향 4
• 1.3 연구 목적 4
• 1.4 연구의 구성 5
• Reference 7
• 2. 수리모형실험· 9
• 2.1 실험시설 개요· 9
• 2.2 목표파랑의 조파제어 및 계측 시스템 11
• 2.3 상사 및 모형축척의 결정 12
• 2.4 실험대상 구조물의 설정 및 모형 제작 14
• 2.5 월파량 계측 방법 16
• Reference· 17
• 3. 기존 평균 월파량 경험식 고찰 18
• 3.1 평균 월파량 예측 18
• 3.2 조도 저감계수에 대한 기존 연구· 21
• Reference· 27
• 4. 평균 월파량 실험조건 및 결과 29
• 4.1 무차원 변수와 월파량과의 상관관계· 29
• 4.2 입·반사 분리 30
• 4.2.1 Goda 방법· 30
• 4.2.2 Mansard and Funke 방법 33
• 4.3 파랑 및 여유마루 조건· 38
• 4.4 각 단면별 평균월파량 계측결과 40
• 4.4.1 직립식 상치구조물 40
• 4.4.2 반파형 상치구조물 45
• Reference· 51
• 5. 월파 저감계수의 산정 52
• 5.1 EurOtop 2018 매뉴얼의 적용성 검토· 52
• 5.2 Levenberg-Marquardt (LM) 알고리즘의 적용· 54
• 5.3 월파량 저감계수의 제안 56
• 5.3.1 고정 월파저감계수 적용 57
• 5.3.2 지수형 월파저감계수 적용· 60
• 5.3.3 역함수형 월파저감계수 적용 63
• 5.3.4 선형 근사형 월파저감계수 적용 66
• 5.3.5 최종 월파저감계수 적용 68
• Reference· 70
• 6. 결론 71
• 6.1 직립식 및 반파형 상치구조물의 월파특성 비교 71
• 6.2 EurOtop 2018 경험식의 적용성 평가와 한계 71
• 6.3 월파저감계수 형태별 비교 및 최종 계수 선정· 72
• 6.4 향후 연구 과제 73
• 초록· 74