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Solifluction processes on permafrost and non-permafrost slopes: results of a large-scale laboratory simulation

Abstract : We present results of full-scale physical modelling of solifluction in two thermally defined environments: (a) seasonal frost penetration but no permafrost, and (b) a seasonally thawed active layer above cold permafrost. Modelling was undertaken at the Laboratoire M2C, Université de Caen-Basse Normandie, Centre National de la Recherche Scientifique, France. Two geometrically similar slope models were constructed using natural frost-susceptible test soil. In Model 1 water was supplied via a basal sand layer during freezing. In Model 2 the basal sand layer contained refrigerated copper tubing that maintained a permafrost table. Soil freezing was from the top down in Model 1 (one-sided freezing) but from the top down and bottom up (two-sided freezing) in Model 2. Thawing occurred from the top down as a result of positive air temperatures. Ice segregation in Model 1 decreased with depth, but in Model 2, simulated rainfall led to summer frost heave associated with ice segregation at the permafrost table, and subsequent two-sided freezing increased basal ice contents further. Thaw consolidation in Model 1 decreased with depth, but in Model 2 was greatest in the ice-rich basal layer. Soil shear strain occurred during thaw consolidation and was accompanied by raised pore water pressures. Displacement profiles showed decreasing movement rates with depth in Model 1 (one-sided freezing) but plug-like displacements of the active layer over a shearing basal zone in Model 2 (two-sided active layer freezing). Volumetric transport rates were approximately 2.8 times higher for a given rate of surface movement in the permafrost model compared with the non-permafrost model. Copyright © 2008 John Wiley & Sons, Ltd.
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https://hal.archives-ouvertes.fr/hal-00358737
Contributor : Valérie Casado-Malaizé Connect in order to contact the contributor
Submitted on : Wednesday, February 4, 2009 - 11:44:14 AM
Last modification on : Tuesday, October 19, 2021 - 11:33:56 PM

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C. Harris, M. Kem-Luetschg, J. Murton, Marianne Font, M. E. Davies, et al.. Solifluction processes on permafrost and non-permafrost slopes: results of a large-scale laboratory simulation. Permafrost and Periglacial Processes, 2008, 19 (4), pp.359-378. ⟨10.1002/ppp.630⟩. ⟨hal-00358737⟩

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