Comparative study of design methods for sliding of perforated wall caisson breakwater

국문 초록 (Abstract)

케이슨 방파제를 설계함에 있어서 방파제의 주요 파괴 모드인 활동에 대하여 안전율을 이용하는 결정론적 설계법이 사용되어 왔다. 하지만 구조물에 작용하는 하중과 구조물의 저항력 등에 대한 불확실성을 안전율이라는 간단하지만 경험적인 상수를 대신하기 때문에 활동량에 대한 정량적, 상대적인 평가가 어려워 구조물을 과대 혹은 과소 설계할 가능성을 내포하고 있다. 이러한 설계변수의 불확실성을 확률적 개념으로 고려하여 케이슨의 활동량을 계산하는 성능 설계법이 제안되고 있다. 무공케이슨 방파제의 성능 설계법은 과거 여러 연구자들에 의해 연구가 진행되어 왔으며, 현재 그 틀이 거의 잡혀져 있다 해도 과언이 아니다. 반면, 유공케이슨 방파제의 경우 전면의 유공벽 구조에 의한 파력 감쇄에 따라 구조물의 안정성이 증대되는 효과가 있음에도 불구하고 이와 관련된 연구는 국내∙외적으로 아직 많이 이루어지지 않았다.
본 연구에서는 기존의 무공케이슨 방파제의 성능 설계법 이론을 유공케이슨 방파제에 확장, 적용하여 이론의 적용 가능성 여부를 판단한다. 또한 결정론적 설계법의 결과와 비교 분석하여 합리적인 설계법을 결정 한다. 이는 유공케이슨 방파제의 성능 설계법에 대한 기준을 제시하기 위해 수행되는 기초 연구이다. 따라서 향후 유공케이슨 방파제의 성능 설계에 매우 중요한 지표가 될 것으로 예상된다.

다국어 초록 (Multilingual Abstract)

In the design of a caisson breakwater against sliding, the deterministic design method has been used with consideration of certain margin of safety factor. However, it is difficult to quantitatively and comparatively evaluate the sliding distance using the safety factor because of the uncertainty of the design variables. It may cause the over- or under-design of the structure. Therefore, it is required to develop probabilistic design methods (e.g., performance-based design method) to consider the uncertainties of the design variables by computing the sliding distance of the caisson. The performance-based design method of a solid-wall caisson breakwater has been investigated by many researchers and its framework is almost completed. On the other hand, researches on a perforated-wall caisson breakwater have been scarcely made despite the fact that it has greater structural safety due to decreased impulsive wave force at the perforated-wall.
In this study, the conventional performance-based design method of the solid-wall caisson breakwater has been expanded and applied to the perforated-wall caisson breakwater in order to examine the feasibility of its application. In addition, a comparative analysis is made between the deterministic design method and performance-based design method. It will serve as a basic research to standardize the criteria of the performance-based design method of a perforated-wall caisson breakwater. Moreover, it is expected to be an important and useful tool in designing a stable perforated-wall caisson breakwater in the future.

목차 (Table of Contents)

• ABSTRACT..................................................................................................... i
• LIST OF TABLES ......................................................................................... v
• LIST OF FIGURES ...................................................................................... vi
• LIST OF SYMBOLS..................................................................................... ix
• CHAPTER 1 INTRODUCTION .................................................................. 1
• 1.1 Necessity and background of research ................................................... 1
• 1.2 Research trends ...................................................................................... 3
• 1.3 Research details and methodology......................................................... 7
• CHAPTER 2 THEORITICAL BACKGROUND ..................................... 10
• 2.1 Deterministic design method................................................................ 10
• 2.2 Reliability design method..................................................................... 12
• 2.2.1 Overview of reliability design method.......................................... 12
• 2.2.2 Level III reliability design method................................................ 13
• 2.2.3 Performance-based design method................................................ 14
• CHAPTER 3 DESIGN VARIABLES......................................................... 18
• 3.1 Deepwater wave ................................................................................... 18
• 3.2 Significant wave period........................................................................ 20
• 3.3 Significant wave height at breakwater site........................................... 22
• 3.3.1 Directional spreading function...................................................... 22
• 3.3.2 Frequency spectrum ...................................................................... 24
• 3.3.3 Wave transformation..................................................................... 25
• 3.4 Individual wave.................................................................................... 31
• 3.5 Calculation of wave force acting on solid-wall caisson breakwater .... 33
• 3.6 Calculation of wave force acting on perforated-wall caisson breakwater .................................................................................................................... 37
• 3.7 Doubly-truncated normal distribution.................................................. 42
• 3.8 Uncertainty of design variables............................................................ 48
• 3.9 Time series of wave force .................................................................... 50
• 3.9.1 Time series of wave force acting on solid-wall caisson................ 50
• 3.9.2 Time series of wave force acting on perforated-wall caisson ....... 53
• 3.10 Expected sliding distance................................................................... 58
• 3.11 Exceedance rate.................................................................................. 60
• CHAPTER 4 RESULTS AND ANALYSIS ............................................... 62
• 4.1 Validation of model.............................................................................. 62
• 4.2 Design conditions of caisson breakwater ............................................. 65
• 4.3 Computation results ............................................................................. 68
• 4.4 Comparison and analysis...................................................................... 84
• CHAPTER 5 CONCLUSIONS AND FUTURE STUDY ......................... 92
• 5.1 Conclusions.......................................................................................... 92
• 5.2 Future study.......................................................................................... 95
• References ..................................................................................................... 97
• 초 록............................................................................................................ 101