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Numerical Examinations of Damage Process on the Chuteway Slabs of Spillway under Various Flow Conditions

여수로 방류에 따른 여수로 바닥슬래브의 손상 발생원인 수치모의 검토

  • Yoo, Hyung Ju (Dept. of Civil & Environmental Engineering, Hongik University) ;
  • Shin, Dong-Hoon (Water Energy & Infrastructure Research Center, K-water) ;
  • Kim, Dong Hyun (Dept. of Civil & Environmental Engineering, Hongik University) ;
  • Lee, Seung Oh (Dept. of Civil & Environmental Engineering, Hongik University)
  • 유형주 (홍익대학교 건설환경공학과) ;
  • 신동훈 (K-water연구원 물인프라안전연구소) ;
  • 김동현 (홍익대학교 건설환경공학과) ;
  • 이승오 (홍익대학교 건설환경공학과)
  • Received : 2021.12.06
  • Accepted : 2021.12.21
  • Published : 2021.12.31

Abstract

Recently, as the occurrence frequency of sudden floods due to climate variability increased, the damage of aging chuteway slabs of spillway are on the rise. Accordingly, a wide array of field survey, hydraulic experiment and numerical simulation have been conducted to find the cause of damage on chuteway slabs. However, these studies generally reviewed the flow characteristics and distribution of pressure on chuteway slabs. Therefore the derivation of damage on chuteway slabs was relatively insufficient in the literature. In this study, the cavitation erosion and hydraulic jacking were assumed to be the causes of damage on chuteway slabs, and the phenomena were reproduced using 3D numerical models, FLOW-3D and COMSOL Multiphysics. In addition, the cavitation index was calculated and the von Mises stress by uplift pressure distribution was compared with tensile and bending strength of concrete to evaluate the possibility of cavitation erosion and hydraulic jacking. As a result of numerical simulation on cavitation erosion and hydraulic jacking under various flow conditions with complete opening gate, the cavitation index in the downstream of spillway was less than 0.3, and the von Mises stress on concrete was 4.6 to 5.0 MPa. When von Mises stress was compared with tensile and bending strength of concrete, the fatigue failure caused by continuous pressure fluctuation occurred on chuteway slabs. Therefore, the cavitation erosion and hydraulic jacking caused by high speed flow were one of the main causes of damage to the chuteway slabs in spillway. However, this study has limitations in that the various shape conditions of damage(cavity and crack) and flow conditions were not considered and Fluid-Structure Interaction (FSI) was not simulated. If these limitations are supplemented and reviewed, it is expected to derive more efficient utilization of the maintenance plan on spillway in the future.

최근 기후변동성으로 인하여 집중호우의 발생빈도 및 강우강도 증가로 노후화된 여수로 바닥슬래브 표면에서의 손상이 발생하여 잦은 보수·보강이 필요한 실정이다. 이를 위해 현장조사, 수리모형 실험 및 수치모형 실험을 통하여 여수로 방류에 따른 손상발생 원인 검토에 관한 연구가 많이 진행되어 왔다. 그러나 대부분의 연구는 일반적으로 여수로의 흐름특성 및 압력분포에 대한 검토를 수행하였을 뿐 손상의 근본적인 발생원인 규명에 관한 연구는 미비한 실정이다. 이에 본 연구에서는 여수로 바닥슬래브 손상발생 원인을 도출하기 위해 공동침식 및 수력잭킹(hydraulic jacking)으로 인한 콘크리트 탈락관점에서 3차원 수치모형인 FLOW-3D와 COMSOL Multiphysics를 사용하여 검토하였다. 또한 공동지수를 산정하고 압력분포로 인하여 구조물이 받는 응력과 콘크리트의 인장·굽힘강도를 비교하여 공동침식 및 수력잭킹으로 인한 콘크리트 탈락 발생 가능성을 확인하였다. 수문 완전개도 조건에서 여수로 방류에 따른 공동침식 및 수력잭킹에 대하여 수치모의를 수행한 결과, 여수로 하류부에서 공동지수가 0.3 미만으로 공동침식 발생 가능성을 확인하였고, 공동부 및 균열부에서 압력분포에 따라 콘크리트가 받는 응력은 4.6~5.0 MPa로 콘크리트 인장강도와 굽힘강도와 비교를 통하여 지속적인 압력변동으로 인한 콘크리트의 피로파괴 또는 휨파괴 가능성을 확인하였다. 따라서 여수로 고유속 흐름에 의한 공동 현상 및 수력잭킹이 여수로 바닥슬래브 손상발생의 다양한 원인 중 하나로 판단하였다. 그러나 본 연구는 다양한 형상 조건 및 방류 시나리오를 적용하고 유체-구조물 상호작용(Fluid-Structure Interaction, FSI)모의를 수행하지 못하였다는 한계점이 있다. 이에 향후에는 한계점을 보완하여 검토한다면 보다 효율적이고 효과적인 여수로 유지관리 방안 도출이 가능할 것으로 기대한다.

Keywords

Acknowledgement

본 연구는 K-water연구원 연구과제 『K-water형 댐시설 유지관리 전략 개발 연구』에 대한 자문의 일부로 수행되었습니다.

References

  1. Bureau of Reclamation (2007). Uplift and Crack Flow Resulting from High Velocity Discharges over Open Offset Joints. Report DSO-07-07. Denver Co. Washington, D.C.: United States Bureau of Reclamation.
  2. Falvey, H. T. (1983). Prevention of Cavitation on Chutes and Spillways. In Frontiers in Hydraulic Engineering. ASCE. pp. 432-437.
  3. Flow Science. (2011). Flow3D User Manual. Santa Fe: NM.
  4. Graham, J. R., Creegan, P. J., Hamilton, W. S., Hendrickson, J. G., Kaden, R. A., McDonald, J. E., and Schrader, E. K. (1987). Erosion of Concrete in Hydraulic Structures. ACI Materials Journal. 84(2): 136-156.
  5. Jeon, T. M., Kim, H. I., Park, H. S., and Baek, U. I. (2006). Design of Emergency Spillway Using Hydraulic and Numerical Model-ImHa Multipurpose Dam. Proceedings of the Korea Water Resources Association Conference. pp. 1726-1731.
  6. Kim, D. G., Park, S. J., Lee, Y. S., and Hwang, J. H. (2008). Spillway Design by Using Numerical Model Experiment - Case Study of AnDong Multipurpose Dam. Proceedings of the Korea Water Resources Association Conference. pp. 1604-1608.
  7. Kim, J. S. (2007). Comparison of Hydraulic Experiment and Numerical Model on Spillway. Water for Future. 40(4): 74-81.
  8. Kim, S. H. and Kim, J. S. (2013). Effect of Chungju Dam Operation for Flood Control in the Upper Han River. Journal of the Korean Society of Civil Engineers. 33(2): 537-548. https://doi.org/10.12652/Ksce.2013.33.2.537
  9. Li, S., Cain, S., Wosnik, M., Miller, C., Kocahan, H., and Wyckoff, R. (2011). Numerical Modeling of Probable Maximum Flood Flowing through a System of Spillways. Journal of Hydraulic Engineering. 137(1): 66-74. https://doi.org/10.1061/(asce)hy.1943-7900.0000279
  10. Pettersson, K. (2012). Design of Aerators for Prevention of Cavitation-The Holjes Dam. TRITA LWR Degree Project.
  11. Shin, D. H., Jung, W. S., Yoo, H. J., and Lee, S. O. (2021). Damages of Chuteway Slabs of Spillway by Water Release. In Proceedings of the Korea Water Resources Association Conference. Korea Water Resources Association. 64-64.
  12. Vanoni, V. A. (Ed.). (2006). Sedimentation Engineering. American Society of Civil Engineers.
  13. Wahl, T. L., Frizell, K. W., and Falvey, H. T. (2019). Uplift Pressures Below Spillway Chute Slabs at Unvented Open Offset Joints. Journal of Hydraulic Engineering. 145(11): 04019039. https://doi.org/10.1061/(asce)hy.1943-7900.0001637
  14. Yoo, H. J., Shin, D. h., and Lee, S. O. (2021). Examinations of Damage Mechanism on the Chuteway Slabs of Spillway under Various Flow Conditions. In Proceedings of the Korea Water Resources Association Conference. Korea Water Resources Association. 251-251.