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An Experimental Study to Evaluate the Subsidence Stability of Riprap Protection without Filters

필터 없는 사석보호공의 유사이탈로 인한 침하 안정성 평가를 위한 실험 연구

  • Ji, Un (Dept. of Civil and Environmental. Engrg., Myongji Univ.) ;
  • Yeo, Woon-Kwang (Dept. of Civil and Environmental. Engrg., Myongji Univ.) ;
  • Lee, Won-Min (Dept. of Civil and Environmental. Engrg., Myongji Univ.)
  • 지운 (명지대학교 토목환경공학과) ;
  • 여운광 (명지대학교 토목환경공학과) ;
  • 이원민 (명지대학교 토목환경공학과)
  • Published : 2008.04.30

Abstract

Many countermeasures for local scour at bridge piers constructed on the river and sea have been developed and researched to protect piers against local scour. The most commonly employed method is riprap protection, which is sometimes required the filter installation between riprap and base layers. However, the construction of stone filters are really hard to perform in the field, require the high cost, or sometimes are impossible. The experimental modeling is conducted to analyze the riprap failure modes and the stability of riprap protection without filters based on the different approach velocity and riprap layer thickness conditions. Also, the stability index to evaluate the performance of riprap protection is developed using the experimental results. The cover and thickness of the riprap layer play a very important role in the stability and thicker riprap layers can prevent a total disintegration of the riprap layer effectively, especially due to winnowing failure.

하천이나 해상에 건설된 교량의 교각에서 발생하는 세굴은 구조물의 안전에 있어서 매우 중요하며 이러한 세굴을 막기 위해 여러 세굴보호공법들의 개발 및 연구가 수행되고 있으며, 현재 현장에서 가장 많이 적용되는 방법으로 사석보호공이 있다. 이러한 사석보호공의 경우 사석과 하상 입자 크기에 따라 그 비율이 기준 이상이 될 경우 사석 층과 하상 사이에 필터 층을 시공해야 하지만 현장여건에 따라 필터시공부분에 막대한 공사비용을 추가하거나 필터 시공이 불가능한 경우도 있다. 본 연구는 수리모형실험을 통해 필터 없는 사석보호공의 붕괴 형태를 분석하고, 세굴을 방지하기 위해 설치하는 사석 세굴보호공이 필터 설치가 반드시 필요한 조건이지만 필터 층 없이 설치될 경우, 포설 두께 및 접근 유속에 따른 침하 안정성을 평가하기 위한 것이다. 실험 결과는 정량적인 분석과 정성적인 분석을 통해 최종적으로 필터 없는 사석 보호공의 안정성 평가 지표를 개발하는데 활용되었다. 접근유속이 증가하거나 사석보호공의 포설두께가 감소할수록 최종침하량은 증가하는 양상을 보였으며, 모든 실험조건에서 경미한 유사이탈은 최종침하량에 도달할 때까지 발생하였다.

Keywords

References

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