Centrifuge Modelling of Solifluction Processes: Displacement Profiles Associated with One-sided and Two-sided Active Layer Freezing

Two sets of small-scale centrifuge experiments were undertaken to simulate solifluction processes associated with one-sided freezing (with no permafrost) and two-sided freezing (with permafrost) within an active layer 0.8-0.9 m thick at the prototype scale. Models were frozen on the laboratory floor under normal acceleration due to gravity and thawed in the centrifuge under an acceleration of 10 gravities. In the one-sided freezing experiment, ice segregation was concentrated near the surface, whereas in the two-sided model it also caused an ice-rich transition zone to form near the base of the active layer. After repeated freeze-thaw cycles the one-sided experiment revealed concave downslope profiles of movement with shear strain decreasing with depth, whereas in the two-sided experiment, convex downslope profiles indicated the greatest shear strain in the basal part of the active layer. Although smaller surface velocities were measured in the two-sided experiment, higher volumetric velocities developed. The centrifuge experiments showed displacement rates similar to field measurements and analogous to full-scale laboratory experiments. Copyright (C) 2008 John Wiley & Sons, Ltd.