Journal of the Korean Geotechnical Society (한국지반공학회논문집)

Korean Geotechnical Society (한국지반공학회)
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Evaluation of the Moment Bearing Capacity of Offshore Bucket Platforms in Sand

사질토 지반에 설치된 해상 버켓작업대의 모멘트 지지력 산정

  • ;
  • 구교영 (서울대학교 건설환경공학부) ;
  • 김성렬 (서울대학교 건설환경공학부)
  • Received : 2019.11.08
  • Accepted : 2019.11.18
  • Published : 2019.12.31
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Abstract

The bucket platform is a new structure suitable for construction of offshore bridge foundations and providing the temporary support for equipments and labour. The platform can be subjected to moment loading due to the eccentric loading or the horizontal load by wave and wind. Therefore, a three dimensional finite element analysis was performed to evaluate the moment bearing capacity of the bucket platform, varying soil density, the diameter and embedment depth of the bucket. The numerical modeling was verified and compared with the moment-rotation curve from a field loading test. The uniform sandy ground was assumed and the moment load was applied at the top plate of the platform, increasing bucket rotation. The moment-rotation relations were analyzed to determine the moment capacity, which was influenced by the embedment depth and diameter of the bucket. Finally, a preliminary design equation was suggested to estimate the moment bearing capacity.

버켓작업대는 새롭게 개발되는 해상 구조물로서 교량기초 등의 시공을 위한 장비 및 인력의 임시 작업공간을 제공하는데 이용된다. 버켓작업대는 작업하중의 편심, 파도 및 바람의 수평하중 등에 의해 모멘트 하중이 작용한다. 그러므로, 본 연구에서는 3차원 유한요소 수치해석을 수행하여 버켓작업대의 모멘트 지지력을 산정하였다. 우선, 버켓에 대한 현장실험 결과와 비교하여 수치모델링의 적용성을 분석하였다. 그리고, 흙의 밀도, 버켓의 직경과 지중 근입깊이 등 다양한 조건에 대한 변수연구를 수행하였다. 지반조건은 균질한 사질토 조건을 적용하였으며 모멘트 하중은 지지대 상판의 중앙지점 회전각을 증가시켜면서 재하하였다. 모멘트-회전 해석결과로부터 모멘트 지지력을 산정한 결과 지지력이 버켓의 직경과 근입깊이에 영향을 받는 것으로 나타났다. 최종적으로 해석결과를 종합하여 버켓작업대의 예비설계를 위한 모멘트 지지력 예측식을 제안하였다.

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References

  1. Achmus, M., Akdag, C. T., and Thieken, K. (2013), "Load-Bearing Behavior of Suction Bucket Foundations in Sand", Applied Ocean Research, Vol.43, pp.157-165. https://doi.org/10.1016/j.apor.2013.09.001
  2. Byrne, B. W. (2000), Investigations of Suction Caissons in Dense Sand, Ph.D. Thesis, University of Oxford, Oxford, U.K.
  3. Byrne, B. W. and Houlsby, G. T. (1999), "Drained Behaviour of Suction Caisson Foundations on Very Dense Sand", Proc. of the Annual Offshore Technology Conference, Houston, Texas, 1, pp. 765-782.
  4. Byrne, B. W. and Houlsby, G. T. (2003), "Foundations for Offshore Wind Turbines", Philosophical Transactions of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences, A362(1813), pp.2909-2930. https://doi.org/10.1098/rsta.2003.1286
  5. EAU (2004), Recommendations of the Committee for Waterfront Structures, Harbours and Waterways, Ernst and Sohn, a Wiley company, Berlin, pp.12-13.
  6. El-Reedy, M. A. (2012), Offshore structures: Design, Construction and Maintenance. Gulf Professional Publishing, Waltham, pp.234.
  7. Ghaseminejad, V., Rowshanzamir, M. A., and Barari, A. (2018), "Predicting the Drained Capacity of Skirted Foundations under Uniaxial Loads", Proc. of GeoShanghai International Conference, Springer, Singapore, pp.718-725.
  8. Graham, J., Pinkney, R. B., Lew, K. V., and Trainor, P. G. S. (1982), "Curve-Fitting and Laboratory Data", Canadian Geotechnical Journal, Vol.19, No.2, pp.201-205. https://doi.org/10.1139/t82-023
  9. Houlsby, G. T. and Byrne, B. W. (2004), "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.
  10. Houlsby, G. T., Kelly, R. B., Huxtable, J., and Byrne, B. W. (2005), "Field Trials of Suction Caissons in Sand for Offshore Wind Turbine Foundations", Geotechnique, Vol.56, No.1.
  11. Ibsen, L. B., Barari, A., and Larsen, K. A. (2014), "Adaptive Plasticity Model for Bucket Foundations", Journal of Engineering Mechanics, Vol.140, No.2, pp.361-373. https://doi.org/10.1061/(asce)em.1943-7889.0000633
  12. Ibsen, L. B., Barari, A., and Larsen, K. A. (2015), "Effect of Embedment on the Plastic Behavior of Bucket Foundations", Journal of Waterway, Port, Coastal, and Ocean Engineering, Vol.141, No.6, 06015005. https://doi.org/10.1061/(ASCE)WW.1943-5460.0000284
  13. Janbu, N. (1963), "Soil Compressibility as Determined by Oedometer and Triaxial Tests", Proc. of European Conference on Soil Mechanics and Foundation Engineering, Wiesbaden, Germany, Vol.1, pp. 19-25.
  14. 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
  15. Mansur, C. I. and Kaufman, R. I. (1956), "Pile Tests, Low-Sill Structures, Old River, La.", Journal of the Soil Mechanics and Foundations Division, Vol.82, No.4, pp.1-33.
  16. Simulia, D. S. (2010), Abaqus. User's Manual. Dassault systems Simulia corp, providence, RI.
  17. Tran, N. X., Hung., L.C., and Kim, S. R. (2017), "Evaluation of Horizontal and Moment Bearing Capacities of Tripod Bucket Foundations in Sand", Ocean Engineering, Vol.140, pp.209-221. https://doi.org/10.1016/j.oceaneng.2017.05.012
  18. Vicent, S. and Kim, S.R. (2018), "Evaluation of the Vertical Bearing Capacity of Offshore Bucket Platforms in Sand", Korean Geotechnical Society, Fall Conference 2018.
  19. Villalobos, F. A. (2006), Model Testing of Foundations for Offshore Wind Turbines, Ph.D. Thesis, University of Oxford.
  20. Villalobos, F. (2007), "Installation of Suction Caissons in Sand", Proc. of the 6th Chilean Conf. of Geotechnics (Congreso Chileno de Geotecnia).
  21. Villalobos, F. A., Byrne, B. W., and Houlsby, G. T. (2009), "An Experimental Study of the Drained Capacity of Suction Caisson Foundations under Monotonic Loading for Offshore Applications" Soils and foundations, Vol.49. No.3, pp.477-488. https://doi.org/10.3208/sandf.49.477