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Model Tests for Examination of Overflow Failure Mechanism on River Levee

하천제방의 월류 붕괴 메커니즘 규명을 위한 모형실험

  • Kim, Jin-Man (Geotechnical Engineering Research Institute, Korea Institute of Civil Engineering and Building Technology) ;
  • Park, Min-Cheol (Department of Civil Engineering, Kumoh National Institute of Technology) ;
  • Moon, In-Jong (Geotechnical Engineering Research Institute, Korea Institute of Civil Engineering and Building Technology) ;
  • Jin, Yoon-Hwa (Department of Civil Engineering, Kumoh National Institute of Technology)
  • Received : 2017.01.10
  • Accepted : 2017.03.13
  • Published : 2017.03.30

Abstract

This research conducted the two types of model tests to examine the failure parameters by levee overflow, those were the pilot-scale levee (model height 0.4~0.8 m) and real scale levee (model height 1.0 m). The procedure of levee failure by overflow was succeeded to the following three steps: At first step, the local scouring on levee slope was happened and the overflow velocity was increased slowly. At second step, the enlarged scouring surface and the rapid overflow velocity were succeeded. At last, the levee section was broken totally and the overflow velocity was decreased because of the wide failure surface of levee. The levee failure angle (${\theta}$) was appeared bigger than slope failure angle of Rankine earth pressure. The enlarged levee height (H) made the faster overflow velocity (${\upsilon}$) of the levees, therefore additional tractive force was applied to it, futhermore the failure angle (${\theta}$) and failure surface (A) were enlarged. Because the sand sample for pilot-scale and real scale tests had the same diameter, the critical scouring velocity of each type was also the same, and the scouring properties were governed by variation of overflow velocity.

본 연구에서는 월류에 의한 붕괴 메커니즘의 규명을 위해 모형제방(제방고 0.4~0.8m)과 실물제방(제방고 1.0m)을 대상으로 월류 붕괴실험을 수행하였다. 월류에 의한 제방붕괴는 1단계에서는 월류에 의해 비탈표면에서 세굴이 발생되었으며, 월류의 유속은 완만히 증가되었다. 2단계에서는 붕괴단면이 커지고 유속도 급격히 증가되었다. 3단계에서는 월류에 의해 제방 단면이 완전히 붕괴되고 붕괴면적이 넓어져 유속이 상대적으로 감소되었다. 월류에 의한 제방의 붕괴각(${\theta}$)은 큰 자중, 감소된 전단저항력 및 월류의 흐름에 의한 추가 소류력으로 인해 랭킨토압의 사면붕괴각보다 크게 나타났다. 제방고(H)가 증가될수록 월류에 의한 제방의 월류 유속(${\upsilon}$)이 증가되었으며, 이로 인해 소류력이 추가로 작용되어 제방의 붕괴각(${\theta}$)과 붕괴면적(A)이 함께 증가되었다. 모형실험과 실물실험에 사용된 모래 시료가 동일한 입경크기로 한계세굴유속이 같아 월류 유속변화에 의해 세굴 특성이 지배되는 것으로 나타났다.

Keywords

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