Thaw-Consolidation Effects on the Stability of Alpine Talus Slopes in Permafrost


C. Bommer, Department of Civil Engineering, University of Applied Sciences Rapperswil HSR, Oberseestrasse 10, 8640 Rapperswil, Switzerland. E-mail:


The relative contributions of thaw consolidation and slope-parallel seepage to the generation of overall porewater pressure and resultant potential changes in slope stability are determined in two case studies of thawing soils. The first study concerns experimental slopes of frozen silt inclined at 12° and 24° that thawed during scaled centrifuge modelling reported by Harris et al. (2008). The second study concerns a natural slope near Pontresina, eastern Swiss Alps, of coarse-grained talus inclined at 37° and overlying fine-grained soil that contains the permafrost table. In both cases, seepage parallel to the slope was found to contribute much more to the excess porewater pressures in the thawing soils than did thaw consolidation. This suggests that the effects of thaw consolidation on the stability of alpine talus slopes in mountain permafrost may have only minor significance. Copyright © 2012 John Wiley & Sons, Ltd.