• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2017년도 학술발표회
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• pp.329-329
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• 2017

In this study attempted to evaluate the stability of the protection methods by examining hydraulic characteristics of the area around the point in which marine cable protector is installed such as surf zone occurrence point of shore-end submarine cables suitable for coastal marine environmental conditions, flow rate t the tope of the protector and maximum wave height, and to provide basic data for the selection of the optimal protection method. In performing hydraulic model experiments, the topography of submarine cable installation location was reproduced in 2-D sectional channel, and models appropriate for experimental scale and similitude law were produced and installed for each condition of submarine cables and protectors. Since the topography and submarine cable protectors were reproduced and installed in 2-D sectional channel, the exact reproduction of surf and transformation in shallow water zone was possible, and thus the physical properties could be clearly analyzed. For stability review, an experiment to examine the stability was conducted using a wave maker with 50-year frequency design waves as target, and wave height and cycles were applied based on the approximate lowest low water level(Approx. L.L.W), which is the most dangerous in submarine cable protection methods. As for experimental time, typhoon passing time in summer (about 3 hours) was applied, and wave patterns and deviation ratio of the submarine cable protector were investigated after making irregular waves corresponding to design waves. In addition, current meter and wave height meter were installed at the installation location of the submarine cable protector, and the flow rates and wave height at the top of the protector were measured and analyzed to review hydraulic properties.

• 한국해양공학회지
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• 제23권1호
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• pp.96-103
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• 2009

In 2006, Jeju Island in South Korea experienced a crisis, no electricity for three hours anywhere in the entire island. This incident was caused by a domino effect that occurred after one of the submarine power cables connecting the island to Haenam, a coastal city on the mainland, was damaged by an external load, probably from a ship anchor or a steel pile being used in marine farming. This study presents a collision analysis of a new submarine power cable protector called arch type reinforced concrete. For the analysis, a dynamic finite element program, ANSYS AUTODYN, was used to examine the displacement and stress of the submarine power cable protector using different material models (RHT concrete model, Mohr.Coulomb concrete model). In addition, two reinforcing bar spacings, 75 mm and 150 mm, were considered. From the analyses, the effects of the parameters (concrete model and spacing) on the results (displacement and stress) were analyzed, and the relations between the damage and parameters were found.

• 한국전산구조공학회논문집
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• 제24권6호
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• pp.609-616
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• 2011

콘크리트와 철근의 재료모델 그리고 스톡앵커의 낙하거리 변화에 따른 아치형 해저 케이블 보호구조물의 충돌특성을 분석하였다. 콘크리트의 재료모델로는 plastic kinematic모델과 Johnson-Holmquist Concrete모델이, 철근의 재료모델은 선형탄성모델과 plastic kinematic모델이 고려되었다. 스톡앵커의 무게는 2ton이며 낙하거리는 3, 5, 8.83m로 선정되었다. 충돌해석을 위해 유한요소해석 프로그램 ANSYS가 사용되었고, 해석시간 단축을 위해 낙하거리를 초기속도로 변화하는 기법을 사용하였다. 낙하거리 변화에 따른 재료모델의 민감성을 분석한 결과, 콘크리트의 충돌응답은 콘크리트모델에 민감하고 철근의 충돌응답은 일차적으로 철근모델에 이차적으로 콘크리트모델에 민감함을 알 수 있었다.

• 한국해양공학회지
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• 제30권2호
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• pp.109-116
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• 2016

A flexible concrete mattress (FCM) is a structural system for protecting submarine power or communication cables under various load types. To evaluate its of protection performance, a numerical analysis of an FCM under an anchor collision was performed. The explicit dynamics of the finite element analysis program ANSYS were used for the collision analysis. The influences of the steel reinforcement modeling and collision angle of the anchor on the collision behavior of the FCM were estimated. The FCM damage was evaluated based on the results of the numerical analysis considering the numerical modeling and collision environment.

• 한국해양공학회지
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• 제29권1호
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• pp.70-77
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• 2015

The purpose of this study was to provide fundamental data for an anchor collision simulation of an FCM (flexible concrete mattress). Numerical material models (elastic-perfectly plastic model, Drucker-Prager model, and RHT concrete model) were compared. ANSYS Explicit Dynamics was used for collision analyses. An FE model was used for the anchor, FCM, andreinforcement bars. The results showed that the behavior of the FCM was verydifferent that those ofthe material models. In particular, the effect of the pressure dependent strength was most noticeable among the properties of concrete.

• Smart Structures and Systems
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• 제15권2호
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• pp.299-314
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• 2015

Submersed rock-berm structures are frequently used for protection of underwater lifelines such as pipelines and power cables. During the service life, the rock-berm structure can experience several accidental loads such as anchor collision. The consequences can be severe with a certain level of frequency; hence, the structural responses should be carefully understood for implementing a proper structural health monitoring method. However, no study has been made to quantify the structural responses because it is hard to deal with the individual behavior of each rock. Therefore, this study presents a collision analysis of the submersed rock-berm structure using a finite element software package by facilitating the smoothed-particle hydrodynamics (SPH) method. The analysis results were compared with those obtained from the Lagrange method. Moreover, two types of anchors (stock anchor and stockless anchor), three collision points and two different drop velocities (terminal velocity of each anchor and 5 m/s) were selected to investigate the changes in the responses. Finally, the effect of these parameters (analysis method, anchor type, collision point and drop velocity) on the analysis results was studied. Accordingly, the effectiveness of the SPH method is verified, a safe rock-berm height (over 1 m) is proposed, and a gauge point (0.5 m above the seabed) is suggested for a structural health monitoring implementation.