Journal of the Korean GEO-environmental Society (한국지반환경공학회 논문집)

Korean Geo-Environmental Society (한국지반환경공학회)
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Estimation of Overflow-Induced Pressure and Velocity on a Mound-Type Sea Dike

월류 시 마운드형태 방조제에 작용하는 압력과 유속 산정

  • Received : 2014.09.10
  • Accepted : 2015.01.19
  • Published : 2015.03.01
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Abstract

Wave overflow can cause a failure of sea dike structure. Based on the results of the field surveys on mound-type sea dike, the failure of vicinity of crown and the scouring of toe at the landward was revealed as the most representative failure example. One of the main factors related to this failure pattern is overflow-induced pressure and velocity. Thus, in this study the analytical equations which can determine the pressure and the velocity induced by overflow in sea dike were proposed and verified. To accomplish this, assumed that the flow is quasi-steady and irrotational, and concentric circular streamlines around the vicinity of crown and toe of the sea dike. Flow was assumed as critical state and Bernoulli equation was used to develop the equations that can determine the pressure and velocity at the vicinity of crown and toe of the sea dike. Using these equations, the pressure and the velocity were calculated in condition of various overflow depths and radiuses of circular streamline. Based on the calculation results, while a negative pressure was occurred at the vicinity of crown, a significant amount of positive pressure occurred at the toe. The existence of flow-induced shear stresses was also confirmed. In addition, the limitation of the proposed equations was discussed.

해일에 의한 바닷물의 월류는 방조제 구조물에 피해를 유발시킨다. 지금까지 발생된 마운드 형태 방조제의 파괴 유형 조사 결과, 육지 쪽 마루부 파손과 선단부의 세굴이 대표적인 파괴 사례로 지목되었다. 이와 같은 파괴를 유발하는 가장 큰 원인은 월류에 의해 발생된 압력과 유속이다. 본 연구에서는 에너지 관점에서 마운드 형태 방조제에서 압력과 유속을 산정할 수 있는 이론해를 제안하고 검증하였다. 이를 위해 방조제 마루부와 선단부에 흐름을 유사정적비회전류로 보고 동심원유선이 형성된다고 가정하였다. 한계흐름조건과 베르누이정리를 이용하여 방조제 마루부와 배면 선단부에서의 작용하는 압력 및 유속 산정식을 유도하였다. 이들 식을 이용하여 동심원유선 및 월류고를 가정하여 마루부와 선단부에서 압력과 유속을 산정하였다. 그 결과 마루부에서는 부의 압력이 선단부에서는 양의 압력이 각각 크게 작용하는 것으로 나타났으며 유속에 의한 전단응력도 작용하는 것을 확인하였다. 또한 제안된 이론해의 적용 한계에 대한 고찰도 이루어졌다.

Keywords

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