Numerical Investigation of Freezing and Thawing Process in Buried Chilled Gas Pipeline

Hosung Shin; Heungrock Park

doi:10.7843/kgs.2016.32.6.17

All Issue

2016 Vol.32, Issue 6 Preview Page Next Page

Numerical Investigation of Freezing and Thawing Process in Buried Chilled Gas Pipeline 매설 냉각가스관의 동결-융해에 대한 수치해석 연구

30 June 2016. pp. 17-26

PDF XML

Abstract

Characteristic behaviors of geo-structure during freezing and thawing process have to be understood based on fundamental knowledge on phase change in porous soil and interaction between soil and structure. Inversion analysis using published one-dimensional soil freezing tests was conducted to suggest a mechanical model to consider an effect of the ice saturation on Young’s modulus. Silty soil was more sensitive to temperature than weathered granite soil and sand, and weathered granite soil was more affected by initial water saturation in stiffness decrease than silty soil. Numerical simulations on chilled gas pipeline showed that shielding effect from surrounding frozen zone around the pipe decreases impact from external load onto the pipe. And a pipe installed in sand backfill showed more heaving due to relatively low stiffness of sand during freezing than that of surrounding in-situ weather granite soil. However, it had more stable stress condition due to effective stress redistribution from external load.

Keywords

Frozen soil

THM coupling

Chilled gas pipeline

지반의 동결-융해 과정에 의한 지반구조물의 거동 특성을 이해하기 위해서는 동결에 의한 지반의 상변화와 구조물과의 상호작용에 대한 연구가 필요하다. 본 연구에서는 기존의 동상 팽창 실험결과에 대한 역해석을 수행하여 얼음포화도에 따란 탄성계수 모델식을 제시하였다. 실트지반은 화강풍화토와 모래지반에 비하여 탄성계수가 얼음포화도에 대하여 매우 민감하고, 화강풍화토는 실트에 비하여 초기 포화도가 탄성계수에 미치는 영향이 큰 것으로 나타났다. 매설 냉각가스관에 대한 수치해석은 가스관 주변의 연중 동결 영역이 외부 동결하중에 대하여 shield 역할을 하여 추가적인 외력의 영향은 상대적으로 작은 것으로 나타났다. 그리고 모래로 치환된 지반에 설치된 가스관은 주변 원지반(화강풍화토)과 치환 모래의 상대적인 탄성계수의 차이로 히빙량이 크게 나타나지만, 외부하중을 효과적으로 재분배하여 안정적인 응력상태에 도달함을 알 수 있다.

References

1.Andersland, O. B. and Ladanyi, B. (2004), Frozen Ground Engineering, John wiley & Sons.

2.Jaky, J. (1944), “The Coefficient of Earth Pressure at Rest”, J. for Society of Hungarian Architects and Engineers, 78 (22), 355-358.

3.Jamiolkowski, M., Lancellotta, R., LoPresti, D.C.F., and Pallara, O. (1994), “Stiffness of Toyoura Sand at Small and Intermediate Strain”, Proceeding of the 13th International Conference on Soil Mechanics and Foundation Engineering, 1, 169-172.

4.Kang, J.M., Kim, H.S., Hong, S.S., and Kim, Y.S. (2009a), “A Fundamental Study on behavior of Pipeline during Ground Freezing in Vladivostok Site, Russia”, Korean Geo-Environmental conference, pp.254-257.

5.Kang, J.M. and Kim, H.S. (2009b), “An Study on Efficiency and Application of Thermal Siphon in the Permafrost”, International Symposium on Urban Geotechnics, pp.963-966.

6.Klar, A., Soga, K., and Ng, M.Y.A., (2010), “Coupled Deformation- flow Analysis for Methane Hydrate Extraction”, Geotechnique, Vol.60, No.10, pp.765-776.

7.Michalowski, R.L. (2005), “Coefficient of Earth Pressure at Rest”, J. Geotech. Geoenviron. Eng., Vol.131, No.11, pp.1429-1433

8.Penner, E. (1967), “Heaving Pressure in Soils during Unidirectional Freezing”, Canadian Geotechnical Journal, Vol.4, No.4, pp.398-408

9.Qian, J., Yu, Q., Guo, L., and Hu, J. (2013), “Experimental Study on Convection Characteristics of Crushed-rock Layer”, Can Geotech J., Vol.50, No.8, pp.834-840.

10.Santamarina, J.C. and Fratta, D. (2005), Discrete Signals and Inverse Problems, Wiley, New York.

11.Shin, E.C. and Park, J.J. (2003), “An Experimental Study on Frost Heaving Pressure Characteristics of Frozen Soils”, Journal of Korean Geotechnical Society, Vol.19, No.2, pp.65-74.

12.Shin, H., Kim, J.M., Lee, J., and Lee, S.R. (2012), “Mechanical Constitutive Model for Frozen Soil”, Journal of Korean Geotechnical Society, Vol.28, No.5, pp.85-94.

13.Uchida, S., Soga, K., and Yamamoto, K. (2012), “Critical State Soil Constitutive Model for Methane Hydrate Soil”, J. Geophys. Res., 117, B03209, doi:10.1029/2011JB008661

14.Yao, X., Qi, J., and Yu, F. (2014), “Study on Lateral Earth Pressure Coefficient at Rest for Frozen Soils”, Journal of Offshore Mechanics and Arctic Engineering, 136, DOI: 10.1115/1.4025546

15.Yoo, C. and Shin, B.N. (2011), “Effect of Cyclic Freezing-Thawing on Compressive Strength of Decomposed Granite Soils”, Journal of Korean Geosynthetic Society, Vol.10, No.4, pp.11-20.

Information

Publisher :The Korean Geotechnical Society
Publisher(Ko) :한국지반공학회
Journal Title :Journal of the Korean Geotechnical Society
Journal Title(Ko) :한국지반공학회 논문집
Volume : 32
No :6
Pages :17-26
Received Date : 2016-04-07
Revised Date : 2016-05-22
Accepted Date : 2016-05-25
DOI :https://doi.org/10.7843/kgs.2016.32.6.17

Journal of the Korean Geotechnical Society ISSN:1229-2427(Print) 2288-646X(Online) 한국지반공학회 논문집

All Issue