Journal of the Korean Geotechnical Society (한국지반공학회논문집)

Korean Geotechnical Society (한국지반공학회)
권호 표지
DOI QR코드

DOI QR Code

Field Installation Test of the Circular Steel Cofferdam Using Suction Pressure

석션압을 이용한 원형강관 가물막이 현장설치 실험

  • Kim, Jae-Hyun (Dept. of Civil Engrg., The College of Art, Culture and Engrg., Kangwon National Univ.) ;
  • Xin, Zhen-Hua (Dept. of Infrastructure Safety Research, Korea Institute of Civil Engrg. and Building Technology) ;
  • Lee, Ju-Hyung (Dept. of Infrastructure Safety Research, Korea Institute of Civil Engrg. and Building Technology)
  • 김재현 (강원대학교 문화.예술공과대학 건축토목환경공학부 토목공학전공) ;
  • 신진화 (한국건설기술연구원 인프라안전연구본부) ;
  • 이주형 (한국건설기술연구원 인프라안전연구본부)
  • Received : 2020.04.14
  • Accepted : 2020.09.09
  • Published : 2020.10.31
Download PDF
⟨ Previous Next ⟩

Abstract

With increasing demand for offshore structures, the demand for temporary structures to help the offshore construction work has increased. A cofferdam is a temporary barrier to stop the inflow of water in the construction site and allows working in the dry condition when the construction is done within the water. However, it is a major cause of construction delays and increased costs because additional works are required to block the water inflow. Recently, in order to overcome the limitations of the conventional cofferdam methods and to increase economic efficiency, a large-diameter steel cofferdam method has been proposed which can be installed quickly in the seabed by using the suction pressure. In this circular steel cofferdam method, the top side of the cofferdam including the top-lid is always exposed above the sea level in order to use it as a water barrier, unlike the conventional suction bucket foundation. After installation, the top-lid of the cofferdam is removed and the water filled inside the cofferdam is discharged to make the interior dry condition. In this study, the circular steel cofferdam with a 5 m inner diameter was fabricated and the installation tests were conducted at the Saemaguem test site. During the experiment, variation of suction pressure, leakage between connections, structure deformation, and inclination of the steel cofferdam were measured and post-analyzed. This study verified the new circular steel cofferdam method and confirmed that the suction installation method can be successfully used for various purposes on offshore structures.

해상(또는 수상) 구조물 시공수요가 증가됨에 따라 해양구조물 시공을 용이하게 하는 임시구조물 수요가 증가하고 있다. 가물막이(cofferdam)는 임시구조물로 해상 작업 시 외부로부터 물을 막아 육상과 동일한 작업환경을 제공한다. 하지만, 물 유입을 차단하기 위한 별도의 시공공정이 필요하기 때문에 공사지연과 건설비 증가의 주원인이 되고 있다. 최근 재래식 가물막이의 문제점을 해결하고 경제성을 높이기 위해 석션압(suction pressure)을 이용해 신속하고 경제적으로 시공이 가능한 대구경 원형강관 가물막이 공법이 제안되었다. 본 공법은 원형강관 가물막이 상부가 수면위로 노출된 상태에서 석션압을 이용해 해저면에 관입되고, 시공 후 내부의 물을 외부로 배출하여 강관자체를 가물막이로 활용한다. 본 연구에서는 원형강관 가물막이 공법을 검증하기 위해 직경 5m인 원형강관 가물막이를 제작하고 새만금 지역에서 실증실험을 실시하였다. 실험 중 원형 강관에 작용하는 석션압, 연결부 누수유무, 수직도(경사도), 구조체의 변형을 각각 계측하였으며 실험결과를 분석하였다. 본 연구를 통해 석션압을 이용한 원형강관 가물막이 공법을 검증하였으며, 석션 설치공법이 다양한 해양 구조물 시공에 활용 될 수 있음을 확인하였다.

Keywords

References

  1. The American Society of Mechanical Engineers (ASME), "Guidelines for Pressure Boundary Bloted Flange Joint Assembly", ASME PCC-1-2010, NY, USA.
  2. Cotter, O. (2010), "Installation of Suction Caisson Foundations for Offshore Renewable Energy Structures", PhD thesis, Oxford University, UK.
  3. Erbrich, C.T. and Tjelta, T.I. (1999), "Installation of Bucket Foundations and Suction Caissons in Sand-geotechnical Performance", Offshore Technology Conference, Houston, USA, paper OTC 10990.
  4. Houlsby, G.T. and Byrne, B.W. (2005), "Design Procedures for Installation of Suction Caissons in Sand", Proceedings of the Institution of Civil Engineers, Geotechnical Engineering, Vol.158, No.3, pp.135-144.
  5. Iskander, M., El-Gharbawy, S., and Olson, R. (2002), "Performance of Suction Caissons in Sand and Clay", Canadian Geotechnical Journal, Vol.39, No.3, pp.576-584. https://doi.org/10.1139/t02-030
  6. Korea Agency for Insfrastructure Technology Advancement (KAIA) (2015), "Development of a Large-diameter Steel Pipe Cofferdam Method for the Offshore Bridge", R&D planning research Report (in Korean).
  7. Kim, J.H., Lee, S.T., and Kim, D.S. (2018), "Evaluation of Soil Disturbance Due to Bucket Installation in Sand", Journal of the Korean Geotechnical Society, Vol.34, No.11, pp.21-31. (in Korean) https://doi.org/10.7843/KGS.2018.34.11.21
  8. Kim, J.S. (2019), "Numerical Investigation on Structural Behavior of a Lid with Stiffeners for Suction-installed Cofferdams", Journal of Korean Society of Hazard Mitigation, Vol.20, No.10, pp.7-17 (in Korean).
  9. Kim, J.S., Jeong, Y.J., and Park, M.S. (2019), "Estimation on External Forces Applied to Suction Caisson Using Seepage Analysis", Journal of the Korean Society of Civil Engineers, Vol.39, No.2, pp.317-325 (in Korean). https://doi.org/10.12652/KSCE.2019.39.2.0317
  10. Larsen, K.A., Ibsen, L.B., and Barari, A. (2013), "Modified Expression for the Failure Criterion of Bucket Foundations Subjected to Combined Loading", Canadian Geotechnical Journal, Vol.50, No.12, pp.1250-1259. https://doi.org/10.1139/cgj-2012-0308
  11. Ministry of Land, Infrastructure and Transport (MOLIT) (2016), "Design Standard of Steel Structural Members (Allowable Stress Design)", KDS 14 30 05 (in Korean).
  12. Ministry of Land, Infrastructure and Transport (MOLIT) (2016), "Design Standard of Steel Bridge (Allowable Stress Design)", KDS 24 14 30 (in Korean).
  13. Park, H.Y., Oh, M.H., Kim, S.W., Han, T.H., and Baek, S.J. (2019), "Model Tests on Verticality Correction using Individual Length Control Method for Lifting Cable during Suction Pile Penetration", Journal of Korean Society of Hazard Mitigation, Vol. 19, No.5, pp.217-223 (in Korean).
  14. Park, H.Y., Oh, M.H., and Kang, H. (2020), "Effect of Lifting Cables Tension on Verticality Correction of Suction Pile during Ground Penetration", Journal of Coastal Disaster Prevention, Vol. 7, No.2, pp.63-72 (in Korean). https://doi.org/10.20481/kscdp.2020.7.2.63
  15. Senpere, D. and Auvergne, G.A. (1982), "Suction Anchor Piles - A Proven Alternative to Driving or Drilling", Offshore Technology Conference, Houston, USA, Paper OTC 4206.
  16. Song, J.U., Lee, J.S., Park, M.C., Byun, Y.H., and Yu, J.D. (2018), "Laboratory Experiments for Evaluating Dynamic Response of Small-scaled Circular Steel Pipe", Journal of the Korean Geotechnical Society, Vol.34, No.11, pp.81-92 (in Korean). https://doi.org/10.7843/KGS.2018.34.11.81
  17. Tjelta, T.I. (1995), "Geotechnical Experience from the Installation of the Europipe Jacket with Bucket Foundations", Offshore Technology Conference, Houston, USA, Paper OTC 7795.
  18. Tjelta, T.I., Guttormsen, T.R., and Hermstad, J. (1986), "Large-scale Penetration Test at a Deepwater Site", Offshore Technology Conference, Houston, USA, Paper OTC 5103.
  19. Tran, M.N. and Randolph, M.F. (2008), "Variation of Suction Pressure during Caisson Installation in Sand", Geotechnique, Vol.58, No.1, pp.1-11. https://doi.org/10.1680/geot.2008.58.1.1
  20. Vicent, S., Tran, V.A., and Kim, S.R. (2017), "Numerical Investigation on Seepage Stability in Offshore Bucket Cut-off Walls", Journal of the Korean Geotechnical Society, Vol.33, No.11, pp.73-82 (in Korean). https://doi.org/10.7843/kgs.2017.33.11.73
  21. Vicent, S., Tran, V.A., and Kim, S.R. (2018), "Numerical Investigation on Seepage Discharge Inside a Cylindrical Cut-off wall", Journal of the Korean Geotechnical Society, Vol.34, No.10, pp.51-60 (in Korean). https://doi.org/10.7843/KGS.2018.34.10.51
  22. Yu, J.D., Park, M.C., Lee, J.S., and Kim, D.H. (2019), "Small-scaled Laboratory Experiments for Dynamic Stability Monitoring of Large Circular Steel Pipe Cofferdam of Marine Bridge Foundation", Journal of the Korean Geotechnical Society, Vol.35, No.12, pp. 123-134 (in Korean).