06 Triggering glide-snow avalanches with low friction geotextiles

Glover James, Witek Max, Röschmann Nadia

  1. Fachhochschule Graubünden, Institut für Bauen im alpinen Raum (IBAR), Chur, Switzerland

Gliding snow avalanches are a result of continual snow pack creep, leading to full failure and sliding. Gliding and failure occurs along the snow-ground interface on slopes between 25 – 35°. The ensuing gliding-snow avalanches cause damages to infrastructure and life. The principal problem they pose is their unpredictability. Gliding snow packs have a considerable impact on the management of ski areas, transport corridors and spatial planning. For example, the onset of a gliding snowpack above the main ski piste on Schilthorn in Mürren (BE) led to closures lasting several months and considerable business losses. With a warming climate there appear to be increasing reports of gliding snow hazards in alpine regions.

Gliding snow problems are managed through either stabilization or artificially triggering a slide. Triggering sliding is attractive because it has the potential to remove the hazard entirely. This proof of concept research seeks to investigate if low friction geotextiles can be applied to slopes reducing the snow pack ground contact friction to a level that gliding snow avalanches are easily triggered. Or alternatively, the accumulation of a significant gliding-snow pack is not even possible to form. Following the winter, the low friction geotextiles are removed and the land is farmed in the spring and summer months.

Low friction materials such as Polytetrafluoroethylene could provide possible solutions. Still little is known of their performance in low temperature conditions over long periods. The experimental set up involves a series of tilting platforms on which different low friction geotextiles are mounted and a natural snow pack is allowed to accumulate. Tilting the platforms, the friction angle of the geotextiles are gained. Additionally, full-scale field experiments are planned to observe if the low friction geotextiles reduce the basal stability sufficiently to cause early glide-snow avalanche release or prevent snow accumulation.