• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2013년도 춘계학술대회 논문집
• /
• pp.91-96
• /
• 2013

In this paper, vibration response of gravity-type caisson breakwater is analyzed to suggest the direction for structural health monitoring (SHM) on harbor caisson structure. To achieve the objective, the following approaches are implemented. Firstly, vibration analysis methods are selected to examine the dynamic characteristics of the lab-scale caisson in the frequency and the modal domain. Secondly, vibration tests on the lab-scale caisson breakwater which is installed in 2-D wave tank were performed under several water level conditions. Thirdly, vibration response of the lab-scale caisson were analyzed in the frequency and modal domain. Finally, the direction of SHM for gravity-type caisson breakwater was suggested.

• 한국해안·해양공학회논문집
• /
• 제21권3호
• /
• pp.209-215
• /
• 2009

케이슨식 방파제의 신뢰성해석 시 파고와 조위의 확률변동성을 고려하기 위한 하중면 이용방법을 제안하였다. 케이슨식 방파제 전면에 전달되는 수평파력과 양력을 전면조위와 파고의 일차함수로 추정하였으며 추정한 하중면을 일계신뢰도법을 이용한 신뢰성 해석에 적용하였다. 수치해석에서 하중면을 이용한 케이슨식 방파제의 활동 및 전도 파괴확률을 산정하였으며 몬테카를로 모사법의 결과와 비교하였다.

• 한국해안·해양공학회논문집
• /
• 제29권6호
• /
• pp.286-304
• /
• 2017

본 연구에서는 어항 등과 같은 소규모 항에서 적용 가능한 격자블록결속에 의한 신형식의 원형유공케이슨을 제안하고, 이러한 방파제의 수리특성을 수치적으로 검토하였다. 본 연구에서 적용한 수치해석 코드는 최근들어 다양한 분야에서 공학적 문제해결을 위해 그 사용예가 급증하고 있는 공중사용허가서(오픈소스 기반) 라이선스 기반의 OpenFOAM(Open Field Operation and Manipulation)에 조파모듈, 투과층 해석모듈, 및 반사파 제어기능 등을 추가한 OLAFOAM을 적용하였다. 본 연구는 먼저, 1) 규칙파 하 3차원슬리트케이슨 방파제에서 파의 파압변동에 대해 기존의 실험 결과와 비교 검토하고, 2) 불규칙파를 조파하여 목표한 파의 재현과 주파수스펙트럼을 비교 검토하여 OLAFOAM의 타당성을 검증하였다. 이로부터 슬리트케이슨과 유사한 원형유공케이슨이 설치된 일정수심의 3차원수치파동수조에 불규칙파를 조파하여 유수실 폭과 유의파고 및 유의주기의 변화에 따른 원형유공케이슨 방파제에서 월파량, 반사율, 파압분포 및 그들의 상호연관성을 면밀히 검토 분석하였다. 이로부터 파압분포는 불투과연직벽체에 대한 Goda 식의 결과보다 매우 작은 결과를 나타내었으며, 반사율은 기존의 슬리트케이슨에서 반사율의 변동범위 내에 존재하는 것을 알 수 있었다.

• 한국해양공학회지
• /
• 제26권1호
• /
• pp.34-40
• /
• 2012

This paper presents an experimental modal analysis of a caisson-type breakwater to produce basic information for the structural health assessment of a caisson structure. To achieve the objective, the following approaches are implemented. First, modal analysis methods are selected to examine the modal characteristics of a caisson structure. Second, experimental modal analyses are performed using finite element analyses and lab-scale model tests. Third, damage scenarios that include several damage levels in a foundation-structure interface are designed. Finally, the effects of damage on the modal characteristics are analyzed for the purpose of utilizing them for damage identification.

• 산업기술연구
• /
• 제31권B호
• /
• pp.81-90
• /
• 2011

Centrifuge modeling and numerical analysis on works of breakwater construction were performed to investigate the behavior of caisson type of breakwater and foundation treated with the method of DCM (Deep Cement Mixing) under the condition of wave action in field. In centrifuge modeling, construction sequence of breakwater caisson such as preparation of ground, treatment of DCM, installation of rubble mound, placement of breakwater caisson and lateral loading on the breakwater due to wave action were reconstructed. Lateral movement of model breakwater and ground reaction in the vertical direction were monitored during test. Stress concentration ratio between the untreated ground and the treated ground with DCM was evaluated from measurement of vertical stresses on each ground. Numerical analysis with the software of PLAXIS was carried to compare with Results of centrifuge model test. It was found that stability of model breakwater was maintained during stage of construction and the compared results about stress concentration ratio were in relatively good agreements.

• 한국해양공학회지
• /
• 제19권1호
• /
• pp.26-32
• /
• 2005

Recent earthquakes, measuring over a magnitude of 5.0, on the eastern coast of Korea, have aroused interest in earthquake analyses and the seismic design of caisson-type breakwaters. Most earthquake analysis methods, such as equivalent static analysis, response spectrum analysis, nonlinear analysis, and capacity analysis, are deterministic and have been used for seismic design and performance evaluation of coastal structures. However, deterministic methods are difficult for reflecting on one of the most important characteristics of earthquakes, i.e. the uncertainty of earthquakes. This paper presents results of probabilistic seismic hazard assessment(PSHA) of an actual caisson-type breakwater, considering uncertainties of earthquake occurrences and soil properties. First, the seismic vulnerability of a structure and the seismic hazard of the site are evaluated, using earthquake sets and a seismic hazard map; then, the seismic risk of the structure is assessed.

• 한국해안·해양공학회논문집
• /
• 제25권1호
• /
• pp.1-10
• /
• 2013

이 연구에서는 대형 항만시설물인 방파제 케이슨에 대한 진동특성 분석을 위한 충격진동시험 적용 결과를 분석하고, 그 결과를 유체-구조물-지반 상호작용을 고려한 수치해석 결과와 비교하여 수치해석 모델의 적용 가능성을 검토하였다. 천단고를 높이기 이전의 오륙도 방파제에 대한 실험결과와 최근 천단고를 높인 이후의 방파제에 대한 실험결과와 비교하여 천단고를 높임으로써 고유주파수가 1.7-4.3% 감소되었음을 알 수 있었고, 수치해석 결과에서도 고유주파수가 감소되는 것으로 분석되어 진동시험 및 수치해석의 합리성을 검증할 수 있었다.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2009년도 세계 도시지반공학 심포지엄
• /
• pp.1258-1270
• /
• 2009

Recently, the earthquakes activities are more of frequency occurred in the country. In case of nomal or large magnitude earthquakes, which cause a rising number of life loss or widespread loss of property. It must be considered how to cope with the situperty of dpmage in the country ty account of ay earthquake. Consequently, the public works have currently ensured against a lot of risk about seismism not only on large scale structures but also relatively small structures. Therefore, in this study, in order to make the seismic stability safe, it has been evaluated by the seismic performance for caisson-type breakwater. The seismic response analyses have conducted on the caisson-type breaker under long-period, short-period and artificial seismic wave. The liquefaction potential of the foundation, which is caisson-type, is also estimated by using the simplified assessment method. Finally, the result of the numerical analysis by PENTAGON 2D finite element method(FEM) program are presented for 3 cases with time-history seismic analysis under the seismic load.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2010년도 춘계 학술발표회
• /
• pp.1473-1478
• /
• 2010

For the cassion type of breakwater under the condition of large wave loads, stability about lateral movement of breakwater was investigated by performing centrifuge model experiments. Prototype of breakwater was modelled by scaling down to centrifuge model and the soft ground reinforced with grouting was also reconstructed in the centrifuge model experiments. Sandy ground beneath breakwater was prepared with a soil sampled in field so that identical value of internal friction angle could be obtained. Centrifuge model experiments were carried out to reconstruct the construction sequence in field. Lateral static wave load was applied to the model caisson after the final stage of construction sequence was rebuilt and the measured lateral movement of caisson was compared with allowable value by the code to assess the stability about lateral movement of the breakwater.

• 한국해양공학회지
• /
• 제24권1호
• /
• pp.90-98
• /
• 2010

In this paper, vibration-based structural health monitoring methods that are suitable for caisson-type structures are examined by an experimental evaluation. To achieve the objective, four approaches are implemented. First, vibration-based structural health monitoring methods are selected to monitor the structural condition of caisson-type breakwaters. Second, a lab-scaled caisson structure is constructed to verify the selected monitoring methods. Third, the vibration characteristics are numerically analyzed using an FE model due to the change in the rubble mound condition. Finally, experimental vibration tests of the lab-scaled caisson structure are performed to monitor the vibration responses due to changes in rubble mound conditions and the performances of the selected methods are examined from the monitoring results.