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

Harris, Charles, Kern-Luetschg, Martina, Murton, Julian, Font, Marianne, Davies, Michael and Smith, Fraser (2008) Solifluction processes on permafrost and non-permafrost slopes: results of a large-scale laboratory simulation. Permafrost and Periglacial Processes, 19 (4). pp. 359-378. ISSN 1045-6740

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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, Universit 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.

Item Type: Article
Schools and Departments: School of Global Studies > Geography
Depositing User: Julian Murton
Date Deposited: 06 Feb 2012 15:22
Last Modified: 10 Jul 2013 08:45
URI: http://sro.sussex.ac.uk/id/eprint/11954
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