Journal of Korean Society of Disaster and Security (한국방재안전학회논문집)

Korean Society of Disaster & Security (한국방재안전학회)
권호 표지
DOI QR코드

DOI QR Code

Performance Factors for Delaying Slope Failure through Hydraulic Experiments of Dam Overtopping

댐 월류 수리실험을 통한 사면붕괴지연 성능인자 도출

  • Sung Woo, Lee (Department of Civil Engineering, Sungkyunkwan University) ;
  • Dong Hyun Kim (Department of Civil and Environmental Engineering, Hongik University) ;
  • Seung Oh Lee (Department of Civil and Environmental Engineering, Hongik University)
  • 이성우 (성균관대학교 건설환경공학과) ;
  • 김동현 (홍익대학교 건설환경공학과) ;
  • 이승오 (홍익대학교 건설환경공학과)
  • Received : 2024.06.07
  • Accepted : 2024.06.17
  • Published : 2024.06.30
Download PDF
⟨ Previous Next ⟩

Abstract

Most reservoirs in South Korea are earthen dams, mainly because they are cost-effective and easy to construct. However, earthen dams are highly vulnerable to seepage and overtopping, making them prone to sudden failure during excessive flooding. Such sudden failures can lead to a rapid increase in flood discharge, causing significant damage to downstream rivers and inhabited areas. This study investigates the effect of riprap placement on the slopes of earthen dams in delaying dam failure. Delaying the failure time is crucial as it allows more time for evacuation, significantly reducing potential casualties, which is essential from a disaster response perspective. Hydraulic experiments were conducted in a straight channel, using two different sizes of riprap for protection. Unlike previous studies, these experiments were performed under unsteady flow conditions to reflect the impact of rising water levels inside the dam. The target dam for the study was a cofferdam installed in a diversion tunnel. Experimental results indicated that the presence of riprap protection effectively prevented slope failure under the tested conditions. Without riprap protection, increasing the size of the riprap delayed the failure time. This delay can reduce peak discharge, mitigating damage downstream of the dam. Furthermore, these findings can serve as critical reference material for establishing emergency action plans (EAP) for reservoir failure.

국내 저수지의 대부분 흙댐으로 되어있다. 흙댐은 건설비용이 저렴하고, 용이한 시공성을 가지고 있기 때문이다. 그러나 흙댐은 침투나 월류에 매우 취약하기 때문에, 과도한 홍수량이 발생하였을 경우 급격한 붕괴 가능성이 매우 높다. 급격한 붕괴는 급격한 홍수량 증가로 이어져, 하류 하천 또는 민가에 매우 큰 피해를 발생시킬 가능성이 있다. 이에 본 연구에서는 흙댐 사면에 포설한 사석의 흙댐 붕괴 지연효과에 대해 실험연구를 수행하였다. 붕괴시간이 지연되면, 대피시간을 확보하여 인명 피해를 크게 줄일 수 있기 때문에 재난 대응 관점에서 큰 의미가 있다고 판단된다. 수리실험은 직선형 개수로에서 수행하였으며, 보호공 사석의 크기를 2가지로 결정하였다. 기존 선행 실험과는 달리 실험을 부정류로 수행하였으며 이를 통해 댐 내부의 수위 상승 변화 효과를 반영하였다. 대상댐은 도수터널에 설치된 가물막이 댐으로 결정하였다. 실험결과 수행한 실험조건에서 사석보호공이 있는 경우 사면의 붕괴를 방지할 수 있었고, 사석보호공이 없는 경우 사석의 입경 증가에 따라 붕괴 시간 지연 효과가 있는 것으로 나타났다. 이는 첨두 유출량 감소로 댐 하류부의 피해를 감소시키는 효과가 있을 것으로 판단된다. 또한 저수지 붕괴에 대한 비상대처계획(EAP) 수립 시 주요 참고자료로 활용될 수 있을 것이다.

Keywords

References

  1. Chinnarasri, C., T. Tingsanchali, S. Weesakul, and S. Wongwises. (2003). Flow Patterns and Damage of Dike Overtopping. International Journal of Sediment Research. 18(4): 301-309. 
  2. Coleman, S. E., D. P. Andrews, and M. G. Webby. (2002). Overtopping Breaching of Noncohesive Homogeneous Embankments. Journal of Hydraulic Engineering. 128(9): 829-838. 
  3. Cristofano, E. A. (1965). Method of Computing Erosion Rate for Failure of Earthfill Dams. U.S. Bureau of Reclamation, Denver, CO, USA. 1-14. 
  4. Froehlich, D. C. (1995). Embankment Dam Breach Parameters Revisited. Proceedings of the 1st International Conference on Water Resources Engineering, ASCE, New York. 887-891. 
  5. Han, Geon-Yeon. (1986). Forecasting Model for the Floodwave Propagation Resulting from Fill Dam-Break. Doctoral Dissertation. Yonsei University Graduate School. 
  6. Joo, Yo Han, Chang-geon Yeo, and Seung Oh Lee. (2013). Retardation Effect on the Breach of the Earth Filled Embankment Using the Stiffener During Overtopping. KSCE Journal of Civil and Environmental Engineering Research. 33(4): 1377-1387. 
  7. Khan, D. and Z. Ahmad. (2011). Stabilization of Angular-Shaped Riprap under Overtopping Flows. World Academy of Science, Engineering and Technology. 59: 1153-1157. 
  8. Kim, Jin Hong. (2001). Analysis on Embankment Failure due to Overflow. Chung-Ang Journal of Environmental Science, Institute of Environmental Science and Construction Chung-Ang University. 12(2): 97-107. 
  9. Korea Standards Association. (2001). Test Method for Soil Compaction Using a Rammer (KS F 2312). Seoul: KSA. 
  10. Lee, Dal-Won and Jae-Jin Noh. (2012). Behavior of Failure of Agricultural Reservoir Embankment due to Overtopping. CNU Journal of Agricultural Science. 39(3): 427-439. 
  11. Lee, Sang Tae and Jong Tae Lee. (2001). An Experimental Study on the Collapse Phase of a River Leeves (I) - Effects of the Geometric Characteristics of Cross Section. Journal of Korea Water Resources Association. 34(2): 141-154. 
  12. MacDonald, T. C. and J. Langridge-Monopolis. (1984). Breaching Charateristics of Dam Failures. Journal of Hydraulic Engineering. 110(5): 567-586. 
  13. Ministry of Agriculture, Food and Rural Affairs. (2008). Statistical Yearbook of Land and Water Development for Agriculture. Uiwang: KRC. 
  14. National Emergency Management Agency. (2002) Typhoon Rusa Site Damage Investigation Report. Ulsan: NEMA. 
  15. Thornton, C. I., S. R. Abt, C. Clopper, B. N. Scholl, and A. L. Cox. (2012). Rock Stability Testing in Overtopping Flow - 2012. Hydraulics Laboratory Technical Report No. 2012-1. Engineering Research Center, Colorado State University, Fort Collins, CO, USA. 15p. 
  16. Von Thun, J. L. and D. R. Gillette. (1990). Guidance on Breach Parameters. Unpublished Internal Document. U.S. Bureau of Reclamation, Denver, CO, USA. 17p.