Journal of Korean Society of Coastal and Ocean Engineers (한국해안·해양공학회논문집)

Korean Society of Coastal and Ocean Engineers (한국해안·해양공학회)
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Numerical Analysis of the Beach Stabilization Effect of an Asymmetric Ripple Mat

왜도 된 연흔모양 매트의 해빈 안정화 효과 수치해석

  • Cho, Yong Jun (Department of Civil Engineering, University of Seoul)
  • 조용준 (서울시립대학교 토목공학과)
  • Received : 2019.05.24
  • Accepted : 2019.07.10
  • Published : 2019.08.31
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Abstract

Even though the scale of hard structures for beach stabilization should carefully be determined such that these structures do not interrupt the great yearly circulation process of beach sediment in which the self-healing ability of natural beach takes places, massive hard structures such as the submerged breakwater of wide-width are frequently deployed as the beach stabilization measures. On this rationale, asymmetric ripple mat by Irie et al. (1994) can be the alternatives for beach stabilization due to its small scale to replace the preferred submerged breaker of wide-width. The effectiveness of asymmetric ripple mat is determined by how effectively the vortices enforced at the contraction part of flow area over the mat traps the sediment moving toward the offshore by the run-down. In order to verify this hypothesis, we carry out the numerical simulations based on the Navier-Stokes equation and the physically-based morphology model. Numerical results show that the asymmetric ripple mat effectively capture the sediment by forced vortex enforced at the apex of asymmetric ripple mat, and bring these trapped sediments back to the beach, which has been regarded to be the driving mechanism of beach stabilization effect of asymmetric ripple mat.

해빈 안정화를 위해 거치되는 강성 구조물의 규모는 해빈의 자기 치유 능력이 구현되는 해빈 대순환 과정이 훼손되지 않는 범위에서 결정되어야 하나 최근 지나치게 대형화 되어 광폭 잠제도 빈번하게 차용되고 있는 실정이다. 이러한 시각에 기초하면 Irie et al.(1994)가 제안한 왜도 된 연흔모양 매트는 규모가 크지 않다는 점에서 현재 선호되는 광폭잠제의 대안이 될 수 있을 것으로 판단된다. 전술한 왜도 된 연흔모양 매트의 해빈 안정화 효과는 매트의 유수 단면 축소부에서 강제되는 와류가 run-down 시 외해방향으로 이송되는 표사를 얼마나 효과적으로 포획할 수 있느냐에 따라 결정되는 것으로 추정된다. 본 논문에서는 이러한 가설을 확인하기 위해 수치모의를 수행하였다. 수치모형은 Navier-Stokes 식과 물리기반 지형모형으로 구성하였으며, 모의 결과 왜도 된 연흔모양 매트 정점부에서 강제된 와류에 의해 포획된 표사가 해안 방향으로 이송되는 등 왜도 된 연흔모양 매트의 해빈 안정화 효과를 구성하는 주요 기작과 해빈 안정화 효과를 확인할 수 있었다.

Keywords

References

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