Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Assessing snow instability in skier-triggered snow slab avalanches by combining failure initiation and crack propagation
AbstractDry-snow slab avalanches start with a local failure in a weak snowpack layer buried below cohesive snow slab layers. If the size of the failed zone exceeds a critical size, rapid crack propagation occurs possibly followed by slab release if the slope is steep enough. The probability of skier-triggering a slab avalanche is generally characterized by classical stability indices that do not account for crack propagation. In this study, we propose a new model to evaluate the conditions for the onset of crack propagation in skier-triggered slab avalanches. For a given weak layer, the critical crack length characterizing crack propagation propensity was compared to the size of the area where the skier-induced stress exceeds the shear strength of the weak layer. The ratio between both length scales yields a stability criterion combining the processes of failure initiation and crack propagation. The critical crack length was calculated from a recently developed model based on numerical simulations. The skier-induced stress was computed from analytical solutions and finite element simulations to account for slab layering. A detailed sensitivity analysis was performed for simplified snow profiles to characterize the influence of snowpack properties and slab layering on crack propagation propensity. Finally, we applied our approach to manually observed snow profiles and compared our new criterion to Rutschblock scores.
HighlightsEvaluation of snow instability in skier-triggered snow slab avalanches by combining failure initiation and crack propagation.At the depth of the weak layer, the skier crack length refers to the area where the shear stress exceeds the shear strength.Our new model compares the skier crack length to the critical crack length for the onset of crack propagation.Failure initiation is more likely in shear than in compression, even on flat terrain.Failure initiation propensity decreases with increasing weak layer depth but crack propagation propensity is almost constant.Hard basal layers favor failure initiation and crack propagation due to higher stresses at the depth of the weak layer.Skier crack lengths and critical crack lengths, computed for manually observed snow profiles, correlated well with RB scores.
Assessing snow instability in skier-triggered snow slab avalanches by combining failure initiation and crack propagation
AbstractDry-snow slab avalanches start with a local failure in a weak snowpack layer buried below cohesive snow slab layers. If the size of the failed zone exceeds a critical size, rapid crack propagation occurs possibly followed by slab release if the slope is steep enough. The probability of skier-triggering a slab avalanche is generally characterized by classical stability indices that do not account for crack propagation. In this study, we propose a new model to evaluate the conditions for the onset of crack propagation in skier-triggered slab avalanches. For a given weak layer, the critical crack length characterizing crack propagation propensity was compared to the size of the area where the skier-induced stress exceeds the shear strength of the weak layer. The ratio between both length scales yields a stability criterion combining the processes of failure initiation and crack propagation. The critical crack length was calculated from a recently developed model based on numerical simulations. The skier-induced stress was computed from analytical solutions and finite element simulations to account for slab layering. A detailed sensitivity analysis was performed for simplified snow profiles to characterize the influence of snowpack properties and slab layering on crack propagation propensity. Finally, we applied our approach to manually observed snow profiles and compared our new criterion to Rutschblock scores.
HighlightsEvaluation of snow instability in skier-triggered snow slab avalanches by combining failure initiation and crack propagation.At the depth of the weak layer, the skier crack length refers to the area where the shear stress exceeds the shear strength.Our new model compares the skier crack length to the critical crack length for the onset of crack propagation.Failure initiation is more likely in shear than in compression, even on flat terrain.Failure initiation propensity decreases with increasing weak layer depth but crack propagation propensity is almost constant.Hard basal layers favor failure initiation and crack propagation due to higher stresses at the depth of the weak layer.Skier crack lengths and critical crack lengths, computed for manually observed snow profiles, correlated well with RB scores.
Assessing snow instability in skier-triggered snow slab avalanches by combining failure initiation and crack propagation
Gaume, Johan (Autor:in) / Reuter, Benjamin (Autor:in)
Cold Regions, Science and Technology ; 144 ; 6-15
29.05.2017
10 pages
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
| British Library Conference Proceedings | 2004
Snow cover properties for skier triggering of avalanches
| British Library Conference Proceedings | 2001