Describing Snow Instability by Failure Initiation, Crack Propagation, and Slab Tensile Support

Reuter, Benjamin; Schweizer, Jürg

doi:10.1029/2018gl078069

Cited by 49 publications

(47 citation statements)

References 47 publications

(67 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…properties including snow density, elastic modulus, specific fracture energy or weak layer strength (e.g. Reuter et al, 2018).…”

Section: Data Acquisitionmentioning

confidence: 99%

“…when the load is applied during short time scales (<1 s), failure initiation and crack propagation have been established as relevant processes of avalanche release (Haegeli and Schweizer, 2015). Both processes were shown to be relevant for snow instability (Gaume and Reuter, 2017) and modeled from field measurements of the vertical layering (Reuter and Schweizer, 2018). New advances, in particular to model the dynamics rather than only the onset of crack propagation, require a description of the material behavior in the failure zone.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Shear failure of weak snow layers in the first hours after burial

Reuter

Calonne

Adams

2019

Preprint

Self Cite

View full text Add to dashboard Cite

Abstract. In a dry stratified snowcover slab avalanches release following failure in a weak layer below the slab. Typically, such weak layers consist either of persistent grain types or precipitation particles. Experience suggests that non-persistent instabilities often crest during or towards the end of a storm – probably because weak layers of precipitation particles strengthen rapidly. Studies so far have mainly focused on persistent grain types providing only sparse data to describe non-persistent weak layer failure. To understand differences between persistent and non-persistent weak layers we measured fracture mechanical properties relevant for avalanche release in a temporal series of laboratory tests. At defined lag times we tested small layered samples containing a weak layer of surface hoar, facets or decomposing fragmented particles in shear. Highspeed frames from the failure zone and image correlation analysis confirm that weak layers concentrate the shear strain. Failure consistently occurred after 20–30 % of strain energy was dissipated – despite shear strain rates as high 10−2 s−1. Our results of shear modulus and shear fracture toughness compare well with published data. The values for surface hoar and decomposing fragmented particles increased due to sintering. In the first hours after burial both weak layers had similarly low values, indicating they are equally fragile. Only for surface hoar and decomposing fragmented particles could we calibrate a formulation which allows for estimating the shear modulus from SMP signals.

show abstract

“…properties including snow density, elastic modulus, specific fracture energy or weak layer strength (e.g. Reuter et al, 2018).…”

Section: Data Acquisitionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Shear failure of weak snow layers in the first hours after burial

Reuter

Calonne

Adams

2019

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

“…This normal collapse has been proven to have an important effect on the bending and fracture of the slab (Gaume et al, ). The conditions under which this collapse occurs, as well as its relation to failure and strain softening, remain open issues (Reuter & Schweizer, ).…”

Section: Introductionmentioning

confidence: 99%

Snow Failure Modes Under Mixed Loading

Mede

Chambon

Hagenmuller

et al. 2018

Geophysical Research Letters

View full text Add to dashboard Cite

The mechanical response of snow to mixed‐mode shear and normal loading is the key ingredient for snow avalanche modeling and strongly depends on microstructural characteristics. A discrete element numerical model was developed, which enables the simulation of large‐strain response of snow samples directly described by their full microstructure obtained through X‐ray microtomography. The model offers new insights into the failure mechanism as well as postfailure response of snow in mixed‐mode loading. Three distinct failure modes are identified, depending on the value of applied normal stress. Above a certain threshold normal stress, the failure is characterized by a structural collapse that decomposes the snow sample into a set of cohesionless grains. It is shown that the collapse is a dynamic process, which, once initiated, develops independently of shearing. This behavior was consistently observed for different snow types, including faceted crystals typically composing weak layers.

show abstract

“…et al 2017is not a direct fracture mechanics material property, this work is among the first to directly link stability indices (which are based on the strength of materials) and fracture mechanics. Similar efforts were made by Chiaia et al (2008), who consider shear failure only, and Reuter et al (2015), who correlate a new stability index based on finite element analyses with a model for critical lengths for mixedmode crack propagation given by Heierli (2008).…”

Section: Introductionmentioning

confidence: 91%

Modeling snow slab avalanches caused by weak-layer failure – Part 2: Coupled mixed-mode criterion for skier-triggered anticracks

Rosendahl

Weißgraeber

2020

The Cryosphere

View full text Add to dashboard Cite

Abstract. Using the analytical model presented in Part 1 of this two-part paper, a new conceptual understanding of anticrack nucleation in weak layers is proposed. To obtain a sufficient condition for onset of failure, two necessary conditions must be satisfied simultaneously: (i) the weak layer must be overloaded in terms of stress and (ii) the initiating crack must release enough energy for the formation of new surfaces. This so-called coupled criterion was proposed by Leguillon (2002). No assumptions on initial defects within the weak layer are needed. Instead, the failure criterion provides both critical loading and the size of initiating cracks. It only requires the fundamental material properties strength and fracture toughness as inputs. Crack initiation and subsequent propagation are covered by a single criterion containing both a strength-of-materials and a fracture mechanics condition. Analyses of skier-loaded snowpacks show the impact of slab thickness and slope angle on critical loading and crack initiation length. In the limit cases of very thick slabs and very steep slopes, we obtain natural avalanche release. A discussion of different mixed-mode stress and energy criteria reveals that a wrong choice of mixed-mode hypotheses can yield unphysical results. The effect of material parameters such as density and compliance on weak-layer collapse is illustrated. The framework presented in this two-part series harnesses the efficiency of closed-form solutions to provide fast and physically sound predictions of critical snowpack loads using a new conceptual understanding of mixed-mode weak-layer failure. It emphasized the importance of both stress and energy in avalanche release.

show abstract

Describing Snow Instability by Failure Initiation, Crack Propagation, and Slab Tensile Support

Cited by 49 publications

References 47 publications

Shear failure of weak snow layers in the first hours after burial

Shear failure of weak snow layers in the first hours after burial

Snow Failure Modes Under Mixed Loading

Modeling snow slab avalanches caused by weak-layer failure – Part 2: Coupled mixed-mode criterion for skier-triggered anticracks

Contact Info

Product

Resources

About