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Modelling of cryogenic processes in permafrost and seasonally frozen soils

Thomas, Hywel Rhys, Cleall, Peter John, Li, Y., Harris, C. and Kern-Luetschg, M. 2009. Modelling of cryogenic processes in permafrost and seasonally frozen soils. Géotechnique 59 (3) , pp. 173-184. 10.1680/geot.2009.59.3.173

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Abstract

This paper investigates the thermo-hydro-mechanical (THM) behaviour of soils subjected to seasonal temperature variations in both permafrost and seasonally frozen conditions. Numerical modelling of soil freezing and ice segregation processes is presented, and compared against small-scale physical modelling experiments. The coupled THM model presented, which is solved by way of a transient finite element approach, considers a number of processes, including conduction, convection, phase change, the movement of moisture due to cryogenic suctions, and the development of ice lenses. Two seasonal freezing scenarios are considered: (a) for soils with no permafrost, where freezing is from the surface downward (one-sided freezing); and (b) for soils underlain by permafrost, where large thermal gradients in the uppermost permafrost layer can cause active layer freezing in two directions, from the permafrost table upwards and from the ground surface downwards (two-sided freezing). In the case of one-sided freezing, ice lens formation occurs as the freezing front advances downwards from the surface, and is limited by water supply. However, during two-sided freezing, ice segregation takes place in a closed system, with ice lenses accumulating at the base of the active layer and near the ground surface, leaving an intervening ice-poor zone. Numerical modelling is able to represent the development of both the thermal field and ice segregation observed in the physical models. The significance of this contrasting ground ice distribution is considered in the context of thaw-related slow mass movement processes (solifluction).

Item Type: Article
Date Type: Publication
Status: Published
Schools: Advanced Research Computing @ Cardiff (ARCCA)
Engineering
Subjects: Q Science > QA Mathematics > QA75 Electronic computers. Computer science
T Technology > TA Engineering (General). Civil engineering (General)
Uncontrolled Keywords: ground freezing; deformation; numerical modelling; temperature effects
Additional Information: Pdf uploaded in accordance with publisher's policy at http://www.sherpa.ac.uk/romeo/issn/0016-8505/ (accessed 24/04/2014).
Publisher: ICE
ISSN: 0016-8505
Date of First Compliant Deposit: 30 March 2016
Last Modified: 04 Jun 2017 02:04
URI: http://orca.cf.ac.uk/id/eprint/8408

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