Journal of the Korean Geotechnical Society (한국지반공학회논문집)

Korean Geotechnical Society (한국지반공학회)
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Assessment of Surface Boundary Conditions for Predicting Ground Temperature Distribution

지중온도 변화 예측을 위한 지표면 경계조건 검토

  • Jang, Changkyu (Graduate Student, Univ. of Science and Technology) ;
  • Choi, Changho (Geotechnical Eng. Research Division, SOC Research Institute, Korea Institute of Construction and Technology) ;
  • Lee, Chulho (Geotechnical Eng. Research Division, SOC Research Institute, Korea Institute of Construction and Technology) ;
  • Lee, Jangguen (Geotechnical Eng. Research Division, SOC Research Institute, Korea Institute of Construction and Technology)
  • 장창규 (과학기술연합대학원대학교) ;
  • 최창호 (한국건설기술연구원 SOC성능연구소 Geo-인프라연구실) ;
  • 이철호 (한국건설기술연구원 SOC성능연구소 Geo-인프라연구실) ;
  • 이장근 (한국건설기술연구원 SOC성능연구소 Geo-인프라연구실)
  • Received : 2013.07.30
  • Accepted : 2013.08.19
  • Published : 2013.08.31
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Abstract

Soil freezing is a phenomenon arising due to temperature difference between atmosphere and ground, and physical properties of soils vary upon the phase change of soil void from liquid to solid (ice). A heat-transfer mechanism for this case can be explained by the conduction in soil layers and the convection on ground surface. Accordingly, the evaluation of proper thermal properties of soils and the convective condition of ground surface is an important task for understanding freezing phenomenon. To describe convection on ground surface, simplified coefficient methods can be applied to deal with various conditions, such as atmospheric temperature, surface vegetation conditions, and soil constituents. In this study, two methods such as n-factor and convection coefficient for the convective ground surface boundary were applied within a commercial numerical program (TEMP/W) for modeling soil freezing phenomenon. Furthermore, the numerical results were compared to laboratory testing results. In the series of the comparison results, the convection coefficient is more appropriate than n-factor method to model the convective boundary condition.

지반의 동결현상은 일반적으로 대기와 지반의 온도차이로 발생하는 열흐름에 의해, 지반에 존재하는 물이 동결되어 지반의 물리적 성질이 변하는 현상을 일컫는다. 동결현상 해석에 필요한 지중온도 변화는 크게 대기와 지반의 경계층에서 발생하는 열유동과 지중 내에서 흙을 구성하는 성분들의 열전도 현상으로 설명할 수 있다. 따라서 지표면의 경계조건과 지반의 열적 특성은 동결지반 온도분포 해석에 중요한 인자들이다. 지표면 경계조건은 대기온도, 지표의 식생상태, 토질조건을 포함한 간편상수법들이 제시되어 있다. 대기온도 변화에 따른 지표의 열전달을 설명하는 대표적인 열물성 값은 지표면에서의 n-factor와 대류 열전달계수이다. 본 연구에서는 대기와 지반의 경계층을 해석하는데 필요한 지표면 n-factor와 대류 열전달계수의 적용성을 분석하고자 실내실험을 수행 하였다. 실내실험 결과를 토대로 상용 수치해석 프로그램인 TEMP/W를 이용하여 각각의 경계층 조건에 따른 지중온도 변화를 해석하고 실내실험을 통해 측정된 온도 데이터와 비교하였다. 결론적으로 n-factor보다 지표면 대류 열전달계수를 적용한 수치 해석 모델이 실내실험 결과와 유사하였다.

Keywords

References

  1. Andersland, O. B. and Ladanyi, B. (2004), Frozen Ground Engineering Second Edition, ASCE, John Wiley & Sons. Inc, pp.58-61.
  2. Carlson, H. (1952), "Calculation of depth of thaw in frozen ground", In: Frost Action in Soils: A Symposium. U.S. National Research Council, Highway Research Board, Washington, DC, pp.192-223.
  3. Chen, S. X. (2008), "Thermal conductivity of sands", Institute of Rock and Soil Mechanics, Vol.44, No.10, pp.1241-1246.
  4. Cote, J. and Konrad, J. M. (2005), "A Generalized Thermal Conductivity Model for Soils and Construction Materials", Canadian Geotechnical Journal, Vol.42, No.2, pp.443-458. https://doi.org/10.1139/t04-106
  5. Farouki, O. T. (1986), Thermal properties of Soils, Series on Rock and Soil Mechanics Vol.11, Trans Tech Publications, Clausthal-Zellerfeld, Germany, pp.91-116.
  6. Freitag, D. R. and McFadden, T. (1997), Introduction to cold regions engineering, New York: ASCE Press, pp.47-78.
  7. Hassan, I. (1978), Energy exchange at atmosphere - Earth interface, UMI Number:EC52376 , pp.1-8.
  8. Johansen, O. (1977), Thermal Conductivity of Soils, Ph.D. dissertation, Trondheim, Norway (U. S. Army Cold Regions Research and Engineering Laboratory (CRREL) Draft Translation637, Hanover, N.H., 1977, pp.248-253.
  9. Kade, A., Romanovsky, V. E., and Walker, D. A. (2006), "The N-factor of Nonsorted Circles Along a Climate Gradient in Arctic Alaska", Wiley Inter Science, Vol.17, pp.279-289.
  10. Karunaratne, K. C. and Burn, C. R. (2003), "Freezing n-factors in discontinuous permafrost terrain, Takhini River, Yukon Territory, Canada", In: Proceedings of the 8th International Conference on Permafrost, Zurich: University of Zurich-Irchel, pp.519-524.
  11. Kersten, M. S. (1949), Laboratory Research for the Determination of the Thermal properties of Soils, ACFEL Technical Report 23, pp.153-182.
  12. Klene, A. E., Nelson, F. E., and Shiklomanov, N. I. (2001), "The N-factor in natural landscapes: variability of air and soil-surface temperatures, Kuparuk river basin, Alaska", Antarctic and Alpine Research, Vol.33, No.2, pp.140-148. https://doi.org/10.2307/1552214
  13. Lu, S., Ren, T., Gong, Y., and Horton, R. (2007), "An improved model for predicting soil thermal conductivity from water content at room temperature", SSSAJ, Vol.71, No.1, pp.8-14. https://doi.org/10.2136/sssaj2006.0041
  14. Osterkamp, T. E. and Burn, C. R. (2003), Permafrost, in Encyclopedia of Atmospheric Sciences, edited by J. R. Holton, pp. 1717-1729.
  15. Oh, M. Y. (2012), An Experimental study on the Creep Behavior of Frozen Soils, Dankook Univ., Seoul, pp.7-34.
  16. Smith, M. W. and Riseborough, D. W. (1996), "Permafrost monitoring and detection of climate change", Permafrost and periglacial processes, Vol.7, Issue 4, pp.301-309. https://doi.org/10.1002/(SICI)1099-1530(199610)7:4<301::AID-PPP231>3.0.CO;2-R
  17. Taylor, A. E. (1995), "Field measurements of n-factors for natural forest areas, Mackenzie Valley, Northwest Territories", Geological Survey of Canada, Current Research, 1995-B, pp.89-98.

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