• Title/Summary/Keyword: Submerged breakwater

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Experimental study on transmission and stability of submerged breakwater (잠제의 전달율과 안정성에 관한 실험적 연구)

  • Kim, Yong-Woo;Yoon, Han-Sam;Kim, Hong-Jin;Ryu, Cheong-Ro;Sohn, Byung-Kyu
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • 2003.10a
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    • pp.213-219
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    • 2003
  • As the 2-D hydraulic experimental results for the submerged rubble-mound structure, we have concerned with their stability/function characteristics of structures by the effects of wave force, scour/deposition at the toe and wave transmission ratio at the lee-side sea. And as to investigate the variation characteristics of wave transmission ratio which depended to a geometrical structure of the submerged breakwater profiles, the critical conditions for the depth of submergence and crest width obviously presented. In summary, there results lead us to the conclusions that the wave control capabilities of submerged breakwaters by the variation of the submergence depth is high about 4 time degrees at the efficiency than the that of crest width. The destruction of covering block at the crest generated at the region which located between maximum damage curve, it maximum damage/failure station from the toe of the structure were 0.2L. As the wave transmission coefficient and the slope of the structure increase, the damage/failure ratio and the maximum scour depth at the toe was extended, respectively. When maximum scour depth happened. The destruction of covering block which located at the toe generated at the front slope destruction. Finally, it was found from the results that the optimization of structure may be obtained by the efficiently decision of the submergence depth and crest width in the permissible range of wave transmission ratio.

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Nonlinear Irregular Waves-current Interaction on Flow Fields with Wave Breaking around Permeable Submerged Breakwater (투과성잠제 주변에서 쇄파를 동반한 불규칙파-흐름장의 상호작용)

  • Lee, Kwang-Ho;Bae, Ju-Hyun;An, Sung-Wook;Kim, Do-Sam
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.30 no.2
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    • pp.39-50
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    • 2018
  • In this study, the nonlinear interaction of irregular waves with wave breaking and currents around permeable submerged breakwater was investigated with the aid of olaFlow model which is open source CFD software published under the GPL license. The irregular wave performance of olaFlow applied in this study was verified by comparing and evaluating the target frequency spectrum and the generated frequency spectrum for applicability to irregular waves. Based on the applicability of this numerical model to irregular wave fields, in the coexistence fields of irregular waves and currents, the characteristics of wave height, frequency spectrum, breaking waves, averaged velocity and turbulent kinetic energy around porous submerged breakwater with the respect to the beach type and current direction versus wave propagation were carefully investigated. The numerical results revealed that the shape of wave breaking on the crown of the submerged breakwater and the formation of the mean flow velocity around the structure depend greatly on the current directions and the type of the beach. In addition, it was found that the wave height fluctuation due to the current direction with respect to the wave propagation is closely related to the turbulent kinetic energy.

Analysis on the Reduction Effects of the Gravity Waves and Infra-Gravity Waves of Detached Submerged Breakwater by Field Monitoring (현장관측을 통한 이안소파잠제의 중력파 및 중력외파 저감효과 검토)

  • Jeong, Weon-Mu;Back, Jong-Dai;Choi, Hyukjin;Kim, Sang-Ik
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.30 no.2
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    • pp.51-60
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    • 2018
  • This study was conducted to observe the effects of gravity and infra-gravity wave of detached submerged breakwater in the coast of Yeongnang-dong, Sokcho, as analyzing continuous wave data by performing field observations on the front area (W0) and rear area (W1, W2). Wave transmission coefficient ($K_t$) of submerged breakwater was analyzed in two parts, short-period wave (gravity wave) and infra-gravity wave. The wave energy reduction effect was analyzed and compared with the value of the design. In case of above wave height 2.0 m at the front area (W0) of the submerged breakwater, the short-period wave height at point W1 is reduced by about 65% and the short-period wave height at point W2 is reduced by about 59%. The depth of crest of submerged breakwater conducted in a sea area differs from the design, and the wave energy reduction effect is analyzed to be smaller than the design plan. The infra-gravity waves were amplified to 2.11 and 1.71 at the W1 and W2 points, respectively, and the wave height at W2 point was smaller than that at W1 point.

Numerical Analysis on Liquefaction Countermeasure of Seabed under Submerged Breakwater using Concrete Mat Cover (for Regular Waves) (콘크리트매트 피복을 이용한 잠제하 해저지반에서의 액상화 대책공법에 관한 수치해석(규칙파 조건))

  • Lee, Kwang-Ho;Ryu, Heung-Won;Kim, Dong-Wook;Kim, Do-Sam;Kim, Tae-Hyung
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.28 no.6
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    • pp.361-374
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    • 2016
  • When the seabed around and under gravity structures such as submerged breakwater is exposed to a large wave action long period, the excess pore pressure is generated significantly due to pore volume change associated with rearrangement soil grains. This effect leads a seabed liquefaction around and under structures as a result from decrease in the effective stress, and the possibility of structure failure is increased eventually. These facts shown above have been investigated in the previous studies related to regular and irregular waves. This study suggested a concrete mat for preventing the seabed liquefaction near the submerged breakwater. The concrete mat was mainly used as a countermeasure for scouring protection in riverbed. According to installation of the concrete mattress, the time and spatial series of the deformation of submerged breakwater, the pore water pressure, and the pore water pressure ratio in the seabed were investigated. Their results were also compared with those of the seabed unprotected with the concrete mat. The results presented were confirmed that the liquefaction potential of seabed under the concrete mattress is significantly reduced under regular wave field.

The Stability Riprap on Scattered Submerged Breakwater due to Physical Model (난적잠제 상부 사석의 안정에 관한 실험적 연구)

  • Park, Sang-Kil;Kim, Woo-Saeng;Lee, Jae-Sung;Kim, Sung-Hun
    • Journal of Ocean Engineering and Technology
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    • v.24 no.1
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    • pp.106-115
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    • 2010
  • This study described the stability of riprap, which was examined by a two-dimensional physical model of a scattered riprap submarine breakwater. Artificial reef structures made of scattered riprap are used like artificial intertidal zone structures as waterfront seaside structures. To prevent topography change in such an artificial intertidal zone the energy is reduced at the scattered riprap submarine breakwater by intercepting high waves. The breaking waves are converted into flow on the front surface slope of the submarine breakwater, which follows the upper part of the artificial intertidal zone. Because of this phenomenon of resisting water flow, it is very important to calculate the required weight of the riprap to maintain its stability. The results of a physical model can be abstracted as shown below. First, distribute the wave breaking types occurring on the front surface slope of the submarine breakwater and arrange it in relation to the movement of riprap. Second, using the hydraulic phenomenon that occurs at the depth of the scattered riprap submarine breakwater, propose a calculation formula for the velocity distribution showing the influence on the stability of the riprap. Third, propose and compare values, which can be obtained by experiments and calculations for riprap stability on the front surface of the artificial intertidal zone. Fourth, calculate the required weight for riprap stability.

Analysis of Bragg Reflection of Waves due to Rectangular Impermeable Submerged Breakwaters with Two-Dimensional Finite Element Method (2차원 유한요소법을 이용한 불투과성 사각형 수중방파제의 Bragg 반사 해석)

  • Cho, Yong-Sik;Jeong, Woo-Chang
    • Journal of Korea Water Resources Association
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    • v.36 no.3 s.134
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    • pp.447-454
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    • 2003
  • The Bragg reflection of monochromatic waves propagating over a rectangular-typed impermeable submerged breakwaters is numerically investigated by using the finite element method. The reflection coefficients calculated from the present model are compared with those of laboratory measurements and the eigenfunction expansion method. A good agreement is observed. The finite element model is also applied to calculate reflection coefficients according to variations of length and width of submerged breakwater.

Numerical Simulation of One-Dimensional Madsen-Sørensen Extended Boussinesq Equations Using Crowhurst-Zhenquan Scheme (Crowhurst-Zhenquan 방법을 이용한 1차원 Madsen-Sørensen 확장형 Boussinesq 방정식의 수치 시뮬레이션)

  • Kang, Sangmuk;Park, Jinsoo;Jang, Taek Soo
    • Journal of Ocean Engineering and Technology
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    • v.31 no.5
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    • pp.346-351
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    • 2017
  • The aim of this paper is to apply the Crowhurst-Zhenquan scheme to one-dimensional Madsen-Sørensen extended Boussinesq equations. In order to verify the application of the aforementioned scheme, the propagation of solitary waves was simulated for two different cases of submarine topography; e.g., a plane beach and submerged breakwater. The simulated results are compared to the results of recent studies and show favorable agreement. The behavior of progressive waves is also investigated.

Submerged Membrane Breakwaters I: A Rahmen Type System Composed of Horizontal and Vertical Membranes (수중 유연막 방파제 I : 수평-수직 유연막으로 구성된 라멘형 시스템)

  • 기성태
    • Journal of Ocean Engineering and Technology
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    • v.16 no.5
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    • pp.7-14
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    • 2002
  • in the present paper, the hydrodynamics properties of a Rahmen type flexible porous breakwater interacting with obliquely or normally incident small amplitude waves are numerically investigated. This system is composed of dual vertical porous membranes hinged at th side edges of a submerged horizontal membrane. The dual vertical membranes are extended downward and hinged at seabed. The effects of permeability, Rahmen type membrane breakwater geometry pre-tensions on membranes, relative dimensionless wave number, and incident Wave headings are thoroughly examined.

Brags Reflection due to Multi-arrayed Semi-circular Submerged Breakwater (반원형 형상 다열 수중방파제에 의한Bragg반사)

  • 전찬후;황종길;조용식
    • Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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    • 2003.08a
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    • pp.249-253
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    • 2003
  • 심해로부터 해안으로 전파해오는 파랑은 해저지형 또는 구조물 등의 영향을 받아 반사, 쇄파 등과 같은 변형을 겪게 되며, 이와 같은 파랑은 연안침식 및 해안구조물의 안전과 설계에 영향을 미친다. 수중방파제(submerged breakwater)는 입사하는 파랑에너지를 대규모로 감소시켜 연안침식을 방지할 뿐만 아니라 방파제를 수중에 건설함으로써 해역환경의 개선을 가능하게 한다. 또한, Bragg반사를 이용하여 수중방파제를 건설할 경우, 연안의 불필요한 침식 및 퇴적현상을 최소화할 수 있을 뿐만 아니라 입사파에 의해 발생하는 해안구조물의 손상을 사전에 방지 할 수 있다. 아울러, 항만의 정온도를 향상시키는데 효과적으로 이용할 수 있다. (중략)

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Analysis of Multi-directional Random Waves Propagating over Multi Arrayed Impermeable Submerged Breakwater (다열 불투과성 수중방파제를 통과하는 다방향 불규칙파랑의 해석)

  • Jung, Jae-Sang;Kang, Kyu-Young;Cho, Yong-Sik
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.19 no.1
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    • pp.29-37
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    • 2007
  • In this study, transmission and reflection of multi-directional random waves propagating over impermeable submerged breakwaters are calculated by using eigenfunction expansion method. A series of mutiderectional random waves is generated by using the Bretschneider-Mitsuyasu frequency and Mitsuyasu type directional spectrum. Strong reflection is occurred at the Bragg reflection condition of the peak frequency. If the row of breakwaters is fixed at 3 and the relative height of breakwater is fixed at 0.6, more than 25% of incident wave energy is reflected to offshore. It is also found that the reflection of directionally spreading random waves increases as the maximum spreading parameter $s_{max}$ increases.