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2015 Vol.31, Issue 7 Preview Page
Vertical Load Transfer Mechanism of Bucket Foundation in Sand

사질토 지반에 설치된 버킷기초의 수직 하중전이 특성

Jeong-Seon Park1
,
Duhee Park2*
,
Se-Woong Yoon3
,
Hwa-Sup Jang4
박 정선1
,
박 두희2*
,
윤 세웅3
,
장 화섭4
1Graduate Student, Dept. of Civil and Environmental Engrg., Hanyang Univ.
2Associate Prof., Dept. of Civil and Environmental Engrg., Hanyang Univ.
3Deputy Senior Surveyor, Korea Register, Technical Division, Research Center
4Senior Surveyor, Korea Register, Technical Division, Research Center
1한양대학교 건설환경공학과 박사과정
2한양대학교 건설환경공학과 부교수
3(사)한국선급 기술본부 연구소 선임연구원
4(사)한국선급 기술본부 연구소 책임연구원
*교신저자. *Corresponding Author. 
31 July 2015. pp. 29-39
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Abstract

The vertical load imposed on the bucket foundation is transferred from the soil inside the bucket to the bottom of the foundation, and also to the outer surface of the skirt. For the design of a bucket foundation installed in sand, the vertical load transfer characteristics have to be clearly identified. However, the response of bucket foundations in sand subjected to a vertical load has not been investigated. In this study, we performed two-dimensional axisymmetric finite element analyses and investigated the vertical load transfer mechanism of bucket foundation installed in sand. The end bearing capacity of bucket foundation is shown to be larger than that of the shallow foundation, whereas the frictional resistance is smaller than that for a pile. The end bearing capacity of the bucket foundation is larger than the shallow foundation because the shear stress acting on the skirt pushes down and enlarges the failure surface. The skin friction is smaller than the pile because the settlement induces horizontal movement of the soil below the tip of the foundation and reduces the normal stress acting at the bottom part of the skirt. The calculated bearing capacity of the bucket foundation is larger than the sum of end bearing capacity of shallow foundation and skin friction of pile. This is because the increment of the end bearing capacity is larger than the reduction in the skin friction.

Keywords
Bucket foundation
Vertical load transfer mechanism
End bearing capacity
Skin friction
Finite element analysis

버킷기초에 작용하는 수직하중의 일부는 내부 흙을 통해 저면으로 나머지는 스커트 외주면과 지반 사이로 전달된다. 사질토 지반에 설치된 버킷기초의 설계를 위해서는 수직 하중전이 특성을 명확하게 규명해야 하나 아직 이에 대한 연구가 수행되지 않았다. 본 연구에서는 2차원 축대칭 유한요소해석을 수행하여 사질토 지반에 설치된 버킷기초의 수직하중에 대한 지반의 응답을 계산하였다. 극한 상태에서 버킷기초의 선단지지력은 얕은기초의 지지력보다 크며 주면마찰력은 말뚝의 설계식에 비하여 작은 것으로 나타났다. 선단지지력은 스커트 외주면에 작용하는 전단응력이 파괴면을 아래로 밀어내어 파괴면이 확장되기 때문에 얕은기초에 비하여 큰 것으로 분석되었다. 반면 주면마찰력은 침하가 진행되면서 버킷기초 하부의 흙이 수평방향으로 밀려 이동하면서 스커트에 작용하는 수평응력이 감소하기 때문에 작은 것으로 나타났다. 버킷기초의 극한지지력은 얕은기초의 선단지지력과 주면마찰력 설계식을 합한 값보다 큰 것으로 계산되었다. 이는 주면마찰력은 설계식보다 작지만 크기가 선단지지력에 비하여 매우 작아 지지력에 큰 영향을 미치지 않는 반면 선단지지력은 주면마찰력에 비하여 증가폭이 크기 때문이다.

References
1
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.
2
2.Bransby, F. and Randolph, M. (1999), “The Effect of Embedment Depth on the Undrained Response of Skirted Foundations to Combined Loading”, SOIL AND FOUNDATIONS, Vol.39, No.4, pp.19-33.
3
3.Bransby, M. F. and Randolph, M. F. (1997), “Shallow Foundations Subject to Combined Loadings”, 9th International Conference of the International Association for Computer Methods and Advances in Geomec, 3, pp.1947-1952.
4
4.Bransby, M. F. and Yun, G. J. (2009), “The Undrained Capacity of Skirted Strip Foundations under Combined Loading”, Geotechnique, Vol.59, No.2, pp.115-125.
5
5.Brinkgreve, R. B. J. and Vermeer, P. A. (1999), Plaxis: finite element code for soil and rock analyses: version 7, Balkema.
6
6.Eid, H. T. (2013), “Bearing Capacity and Settlement of Skirted Shallow Foundations on Sand”, International Journal of Geomechanics, Vol.13, No.5, pp.645-652.
7
7.Gourvenec, S. (2008), “Effect of Embedment on the Undrained Capacity of Shallow Foundations under General Loading”, Geotechnique, Vol.58, No.3, pp.177-185.
8
8.Gourvenec, S. and Randolph, M. (2003), “Effect of Strength Non- homogeneity on the Shape of Failure Envelopes for Combined Loading of Strip and Circular Foundations on Clay”, Geotechnique, Vol.53, No.6, pp.575-586.
9
9.Houlsby, G. T., Ibsen, L. B., and Byrne, B. W. (2005), “Suction Caissons for Wind Turbines”, Frontiers in Offshore Geotechnics: ISFOG, Perth, WA, Australia, pp.75-93.
10
10.Hu, Y., Randolph, M., and Watson, P. (1999), “Bearing Response of Skirted Foundation on Nonhomogeneous Soil”, Journal of Geotechnical and Geoenvironmental Engineering, Vol.125, No.11, pp.924-935.
11
11.Hung, L. C. and Kim, S. R. (2012), “Evaluation of Vertical and Horizontal Bearing Capacities of Bucket Foundations in Clay”, Ocean Engineering, Vol.52, pp.75-82.
12
12.Hung, L. C. and Kim, S. R. (2014), “Evaluation of Undrained Bearing Capacities of Bucket Foundations under Combined Loads”, Marine Georesources & Geotechnology, Vol.32, No.1, pp.76-92.
13
13.Itasca (2011), FLAC, Fast Lagrangian analysis of continua, Minneapolis.
14
14.Kim, D., Youn, J., Jee, S., Choi, J., Lee, J., and Kim, D. (2014), “Numerical Studies on Bearing Capacity Factor Nγ and Shape Factor of Strip and Circular Footings in Sand According to Dilatancy Angle”, Journal of the Korean geotechnical Society, Vol.30, No.1, pp.49-63.
15
15.Lee, J. and Salgado, R. (2005), “Estimation of Bearing Capacity of Circular Footings on Sands based on Cone Penetration Test”, Journal of Geotechnical and Geoenvironmental Engineering, Vol. 131, No.4, pp.442-452.
16
16.Loukidis, D. and Salgado, R. (2009), “Bearing Capacity of Strip and Circular Footings in Sand using Finite Elements”, Computers and Geotechnics, Vol.36, No.5, pp.871-879.
17
17.Lyamin, A. V., Salgado, R., Sloan, S. W., and Prezzi, M. (2007), “Two-and Three-dimensional Bearing Capacity of Footings in Sand”, Geotechnique, Vol.57, No.8, pp.647-662.
18
18.Potts, D. M., Zdravkovic, L., and Zdravković, L. (2001), Finite element analysis in geotechnical engineering: application, Thomas Telford.
19
19.Simulia (2010), Abaqus user’s manual, Dassault Systèmes Simulia Corp.
20
20.Yun, G. and Bransby, M. F. (2007), “The Undrained Vertical Bearing Capacity of Skirted Foundations”, SOIL AND FOUNDATIONS, Vol.47, No.3, pp.493-505.
21
21.Zhu, B., Byrne, B. W., and Houlsby, G. T. (2012), “Long-term Lateral Cyclic Response of Suction Caisson Foundations in Sand”, Journal of Geotechnical and Geoenvironmental Engineering, Vol.139, No.1, pp.73-83.
Information
  • Publisher :The Korean Geotechnical Society
  • Publisher(Ko) :한국지반공학회
  • Journal Title :Journal of the Korean Geotechnical Society
  • Journal Title(Ko) :한국지반공학회 논문집
  • Volume : 31
  • No :7
  • Pages :29-39
  • Received Date : 2015-05-06
  • Revised Date : 2014-07-01
  • Accepted Date : 2015-07-02
  • DOI :https://doi.org/10.7843/kgs.2015.31.7.29
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