Journal of the Korean GEO-environmental Society (한국지반환경공학회 논문집)

Korean Geo-Environmental Society (한국지반환경공학회)
권호 표지

A study for Shear Strength Characteristics of Frozen Soils under Various Temperature Conditions and Vertical Confining Pressures

동결온도조건 및 수직구속응력에 따른 동결토의 전단강도 변화에 관한 연구

  • 이준용 (한국건설기술연구원 Geo인프라연구실) ;
  • 최창호 (한국건설기술연구원 Geo인프라연구실)
  • Published : 2012.11.01
⟨ Previous Next ⟩

Abstract

In order to characterize the shear strength of the frozen sand for foundation design in cold region and prediction of adfreeze bond strength, many researchers developed test techniques and carried out many tests to analyze shear strength properties of the frozen sand for half a century. However, many studies for shear strength properties of the frozen sand have been carried out with limited circumstances, even though shear strength of the froze sand can be affected by various influence factors such as soil type, temperature conditions, and magnitude of normal stress. In this study, direct shear test equipment was used to analyze the shear strength characteristics of the frozen sand. Direct shear test equipment was designed for cold weather, and the direct shear tests were carried out inside of large-scaled low temperature chamber. Three soil types-two uniform sands and one well graded soil were used to analyze the shear strength of the frozen sand with three different temperature conditions and three different vertical confining pressures. In this research, a series of direct shear tests for shear strength of the frozen sand have been conducted to demonstrate the efficiency of effectiveness of the test equipment and low temperature chamber. This research also showed that shear strength of the froze sand increased with decreasing temperature condition, but the influence of vertical confining pressure was insignificant to the shear strength of the frozen sand.

동토지반의 기초구조물을 설계하는데 있어 기초의 안정성을 지배하는 설계정수인 동결토의 전단강도 및 동착강도를 측정하기 위하여 지난 50여 년 동안 많은 연구가 수행되어 오고 있다. 하지만, 아직까지 동결토의 전단강도 특성에 관한 많은 연구들은 토사 종류, 수직구속응력, 동결온도조건 등 여러 가지 영향인자 중 제한된 영향인자의 변화를 통해 수행되어 왔다. 동결토는 일반 토질과는 달리 토립자, 물, 공기뿐만 아니라 얼음을 포함한 4상으로 구성되어 있으며, 동토의 역학적인 성질의 변화는 일반적으로 온도, 수직구속응력, 동토의 구성물질에 따라 영향을 받는다. 이와 같은 동결토의 전단강도 특성을 측정하기 위하여 영하 30도의 저온환경에서도 동작이 가능하도록 설계된 동결토 직접전단시험기를 활용하였으며, 동토지역의 저온환경을 모사하기 위하여 대형 냉동챔버 내에 직접전단시험기를 설치하였다. 동결토의 전단강도 특성을 측정하기 위하여 비교적 균질한 입경분포를 지닌 주문진표준사 및 실리카모래와 입도분포가 좋은 화강풍화토를 활용하였다. 각각 세가지 시료에 대하여 전단시험은 세가지 동결온도 조건 및 수직구속응력 조건에서 수행되었으며, 그 결과를 바탕으로 동결온도조건 및 수직구속응력이 동결토의 전단강도에 미치는 영향을 분석하였다. 전반적으로 동결토의 전단강도는 동결온도가 낮아질수록 증가하는 경향을 보였으나, 수직구속응력에 의한 영향은 미미한 것으로 나타났다.

Keywords

References

  1. Bardet, J. P. (1997), Experimental Soil Mechanics, Prentice Hall, Inc., Upper Saddle River, New Jersey, pp. 421-442.
  2. Bowles, J. E. (1996), Foundation Analysis and Design 5th ed., McGraw-Hill, New York, pp. 472-533.
  3. Bragg, R. A. and Andersland, O. B.(1981), Strain Rate Temperature and Simple Size Effects on Compressions and Tensile Properties of Frozen Sand, Engineering Geology, Vol. 18, No. 1-4, pp. 35-46. https://doi.org/10.1016/0013-7952(81)90044-2
  4. Choi, C. and Ko, S.(2011), A Study for Predicting Adfreeze Bond Strength from Shear Strength of Frozen Sand, Journal of Korean Geotechnical Society, Vol. 27, No. 10, pp. 13-23. https://doi.org/10.7843/kgs.2011.27.10.013
  5. Christ, M., Kim, Y. C., and Park, K. B.(2009), Shear Strength of Frozen Sand, 2009 Conference Co-Hosted by KISTEC & KGES, pp. 394-399.
  6. Cutbertson-Black, R.(2001), The Interaction between a Flighted Steel Pipe Pile and Frozen Sand, Master's Thesis, University of Monitoba, Monitoba, Canada, pp. 34-56.
  7. Fang, H-U.(1991), Foundation Engineering Handbook, Van Nortrand Reinhold, New York, pp. 735-749.
  8. Fitzsimons, S. J., McManus, L. J., Sirota, P., and Lorrain, R. D.(2001), Direct Shear Tests of Materials from a Cold Glacier: Implications for Landform Development, Quaternary International, Vol. 86, No. 1, pp. 129-137. https://doi.org/10.1016/S1040-6182(01)00055-6
  9. Freitag, D. R. and McFadden, T.(1997), Introduction to Cold Regions Engineering, ASCE Press, New York. pp. 291-301.
  10. Ko, S. and Choi, C. (2011), Experimental Study on Adfreeze Bond Strength Bewteen Frozen Sand and Aluminum with Varying Freezing Temperature and Vertical Confining Pressure, Journal of Korean Geotechnical Society, Vol. 27, No. 9, pp. 67-76. https://doi.org/10.7843/kgs.2011.27.9.067
  11. KSF 2343(2007), Standard Test Method for Direct Shear Test of Soils Under Consolidated Drained Conditions, Korean Standards Association, pp. 1-5.
  12. Ladanyi, B. and Johnston, G. H.(1974), Behavior of Circular Footings and Plate Anchors Embedded in Permafrost, Canadian Geotechnical Journal, Vol. 11, No. 4, pp. 531-553. https://doi.org/10.1139/t74-057
  13. Ladanyi, B. and Theriault, A.(1990), A Study of Some Factors Affecting the Adfreeze Bond of Piles in Permafrost, Proc. of Geotechnical Engineering Congress GSP 27 ASCE, Vol. 1, pp. 213-224.
  14. Linell, K. A. and Lobacz, E. F.(1980), Design and Construction of Foundations in Areas of Deep Seasonal Frost and Permafrost, Special Report of Cold Regions Research Engineering Laboratory, U.S. Army, pp. 80-134.
  15. Moosavi, M. and Bawden, W. F.(2003), Shear Strength of Portland Cement Groud, Cement and Concrete Composite, Vol. 25, No. 1, pp. 729-735. https://doi.org/10.1016/S0958-9465(02)00101-4
  16. Phukan, A.(1985), Frozen Ground Engineering, Practice-Hall, New Jersey, pp. 190-199.
  17. Sanger, F. J.(1969), Foundations of Structures in Cold Regions, U.S. Army Cold Regions Research and Engineering Laboratory Monography III-C4, pp. 91.
  18. U. S. Army and Air Force(1983), Arctic and Subarctic Construction Foundation for Structures, Department of The Army and The Air Force, pp. 92-109.
  19. Weaver, J. S. and Morgenstern, N. R.(1981), Pile Design in Permafrost, Canadian Geotechnical Journal, Vol. 18, No. 3, pp. 357-370. https://doi.org/10.1139/t81-043
  20. Yasufuku, N. and Springman, S. M., Areson, L. U. and Ramhold, T.(2003), Stress-dilatancy Behavior of Frozen Sand in Direct Shear, Proc. of the Eighth International Conference on Permafrost, Zurich, Switzerland, pp. 1253-1258.
  21. Zhu, Y., Zhang, J., and Shen, Z.(1988), Uniaxial Compressive Strength of Frozen Medium Sand under Constant Deformation Rates, 5th International Symposium on Ground Freezing, Johnes & Holden(eds), Balkema, Rotterdam, pp. 225-232.