Journal of the Korean Geotechnical Society (한국지반공학회논문집)

Korean Geotechnical Society (한국지반공학회)
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Case History Evaluation of Axial Behavior of Micropiles

소구경말뚝의 축방향 거동에 대한 사례 연구

  • Jeon Sang-Soo (Korea Highway & Transportation Technology, Korea Highway Corporation)
  • Published : 2004.09.01
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Abstract

This paper examines the results of full-scale field tests on micropiles and side resistance is evaluated with respect to axial displacements and soil properties. Both cohesive and cohesionless soils are included in this evaluation. For all practical purposes, the developed load-displacement relationship and the geotechnical soil properties for each micropile and soil type can be used to represent the available data well through normalized average values and empirical correlations. There is a significant difference in load-carrying capacity between micropiles and drilled shafts that results primarily from the micropile pressure-grouting installation effects on the state of stress in the ground. The results show that micropiles can have a significant increase of capacity over larger-diameter drilled shafts at shallower depths with D/B < 100 or so. In cohesive soils, the typical increase is on the order of 1.5 with values as high as 2.5. For cohesionless soils, the typical increases are in the range of 1.5 to 2.5 with values as high as 6.

본 논문은 소구경말뚝의 현장시험결과를 조사하고 축방향 변위와 흙의 성질과의 상관관계에 따른 말뚝의 주변마찰력을 산정하기 위하여 종합적으로 검토하였다. 점착력과 비점착력의 성질을 가진 흙에 대하여 조사를 하였다. 현장적용 목적에 부합한 소구경말뚝의 하중-변위관계와 지반공학적 흙의 특성 그리고 흙의 종류에 대한 연구가 정규화평균값과 경험관계식을 통하여 이루어졌다. 대구경말뚝과 압력-그라우팅 설치 효과로 인한 소구경말뚝의 하중전이로 인한 지지력은 현저한 차이가 있었다. 특히 말뚝 근입깊이(D)와 말뚝 직경(B)의 비가 100보다 작은 얕은 깊이에서는 소구경말뚝이 대구경말뚝에 비해 현저하게 뛰어난 지지력을 가지고 있음을 알 수 있었으며 점착력이 있는 흙에서는 약 1.5에서 최고 2.5배정도 비점착력인 흙에서는 약 1.5에서 2.5배 그리고 최고 6배의 지지력을 갖고 있음을 알 수 있다.

Keywords

References

  1. Bruce, D. A. (1987), 'Rehabilitation of Main Repair Facility, Coney Island', Preliminary Report, Nicholson Construction, Pittsburgh
  2. Bruce, D. A. (1988), 'Aspects of Minipiling Practice in the US', Ground Engineering, Vol.21, No.8, pp.20-33
  3. Bruce, D. A. (1989), 'Aspects of Minipiling Practice in the US', Ground Engineering, Vol.22, No.1, pp.35-39
  4. Bruce, D. A. (1990), 'Pin Pile Performance: Post Grouted Piles at Augusta', GA. Technical Note B-5022, Nicholson Construction, Pittsburgh
  5. Bruce, D. A. and Juran, I. (1997), 'Drilled and Grouted Micropiles: State-of-Practice Review', FHWA-RD-96-016, McLean, July
  6. Bruce, D. A. and Yeung, C. K.A (1984), 'Review of Minipiling, with Particular Regard to Hong Kong Applications', J. Hong Kong Institution of Engineers, pp.31-54
  7. Bruce, D. A., Hall, C. H. and Triplett, R. E. (1992), 'Structural Underpinning by Pinpiles', Proceedings of the 17th Deep Foundations Institute Annual Meeting, New Orleans, pp.49-78
  8. Bruce, D. A., Ingle, J. D. and Jones, M. R. (1985), 'Recent Examples of Underpinning Using Mini- piles', Proceedings of the 2nd International Conference on Structural Faults and Repairs, London, pp.13-28
  9. Chen, J.-R. (1998), 'Case History Evaluation of Axial Behavior of Augered-Cast-In-Place Piles and Pressure-Injected Footing', MS Thesis, Cornell University, Ithaca
  10. Chen, Y.-J. and Kulhawy, F. H. (1994), 'Case History Evaluation of Behavior of Drilled Shafts Under Axial & Lateral Loading', Report TR-104601, Electric Power Research Institute, Palo Alto
  11. Davisson, M. T. (1972), 'High Capacity Piles. Proceedings of Lecture Series on Innovations in Foundation Construction', ASCE Illinois Section, Chicago
  12. Hirany, A. and Kulhawy, F. H. (1988), 'Conduct and Interpretation of Load Tests on Drilled Shaft Foundations: Detailed Guidelines', Report EL-5915 (1), EPRI, Palo Alto
  13. Hirany, A. and Kulhawy, F. H. (1989), 'Interpretation of Load Tests on Drilled Shafts-Part 1: Axial Compression', Foundation Engineering: Current Principles & Practices (GSP 22), Ed. FH Kulhawy, ASCE, New York, pp.1132-1149
  14. Ichimura, Y. and Oshita, T. (2000), 'Applicability of Statnamic Load Test for Micropile', Proceedings of the 3rd International Workshop on Micropiles, Ube, Japan
  15. Jeon, S. S. (2004), 'Interpretation of Load Test on Minipiles', Proceedings of the Institution of Civil Engineers-Geotechnical Engineering, Vol.157, No.2, pp.85-90 https://doi.org/10.1680/geng.2004.157.2.85
  16. Jones, D. A. and Turner, M. J. (1980), 'Load Tests on Post-grouted Micropiles in London Clay', Ground Engineering, Vol.13, No.6, pp.47-53
  17. Koreck, H. W. (1978), 'Small Diameter Bored Injection Piles', Ground Engineering, Vol.11, No.4, pp.14-29
  18. Kulhawy, F. H. (1991), Drilled Shaft Foundations. Chap. 14 in Foundation Eng. Handbook (2/E), Ed. H.-Y. Fang, Van Nostrand Reinhold, New York, pp.537-552
  19. Kulhawy, F. H. and Mayne, P. W. (1990), 'Manual on Estimating Soil Properties for Foundation Design', Report EL-6800, EPRI, Palo Alto
  20. Lizzi, F. (1982) Static Restoration of Monuments, Sagep Publishers, Genoa
  21. Singh, S. and Heine, E. I. (1984), Upgrading Existing Footings with Micro-Piles. Proceedings of International Conference on Case Histories in Geotechnical Eng (3), St. Louis, pp.1373-1383