Shear fracture precipitated by strain softening as a mechanism of dry slab avalanche release

McClung, D. M.

doi:10.1029/jb084ib07p03519

Cited by 132 publications

(152 citation statements)

References 7 publications

(7 reference statements)

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“…The local damage in the weak layer develops into a crack which can expand if its size exceeds a critical length or if the load exceeds a critical value. Finally, crack propagation leads to the tensile fracture of the slab and ultimately, avalanche release (McClung, 1979;Schweizer et al, 2003). During the past decade, our understanding of the fracture process in snow has gradually evolved through the development of new theories as well as various field observations and experiments.…”

Section: Introductionmentioning

confidence: 99%

“…van Herwijnen et al, 2010;. On the other hand, theoretical and numerical models, based on fracture mechanics or strength of material approaches, were developed to investigate crack propagation and avalanche release (McClung, 1979;Chiaia et al, 2008;Gaume et al, 2013Gaume et al, , 2014b. While substantial progress has been made, application with regard to avalanche forecasting or hazard mapping is still hindered in part by our lack of understanding of the dynamic phase of crack propagation.…”

Section: Introductionmentioning

confidence: 99%

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Modeling of crack propagation in weak snowpack layers using the discrete element method

Gaume¹,

Herwijnen²,

Chambon

et al. 2015

The Cryosphere

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Abstract. Dry-snow slab avalanches are generally caused by a sequence of fracture processes including (1) failure initiation in a weak snow layer underlying a cohesive slab, (2) crack propagation within the weak layer and (3) tensile fracture through the slab which leads to its detachment. During the past decades, theoretical and experimental work has gradually led to a better understanding of the fracture process in snow involving the collapse of the structure in the weak layer during fracture. This now allows us to better model failure initiation and the onset of crack propagation, i.e., to estimate the critical length required for crack propagation. On the other hand, our understanding of dynamic crack propagation and fracture arrest propensity is still very limited.To shed more light on this issue, we performed numerical propagation saw test (PST) experiments applying the discrete element (DE) method and compared the numerical results with field measurements based on particle tracking. The goal is to investigate the influence of weak layer failure and the mechanical properties of the slab on crack propagation and fracture arrest propensity. Crack propagation speeds and distances before fracture arrest were derived from the DE simulations for different snowpack configurations and mechanical properties. Then, in order to compare the numerical and experimental results, the slab mechanical properties (Young's modulus and strength) which are not measured in the field were derived from density. The simulations nicely reproduced the process of crack propagation observed in field PSTs. Finally, the mechanical processes at play were analyzed in depth which led to suggestions for minimum column length in field PSTs.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Modeling of crack propagation in weak snowpack layers using the discrete element method

Gaume¹,

Herwijnen²,

Chambon

et al. 2015

The Cryosphere

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“…Most avalanche incidents are caused by dry snow slab avalanches which generally result from a sequence of fracture processes including (1) failure initiation in a weak snow layer underlying a cohesive slab, (2) crack propagation within the weak layer, and (3) slab tensile fracture which leads to its detachment [McClung, 1979;Schweizer et al, 2003]. Due to the multiscale variability of the quantities involved in avalanche release and the complex microstructure of snow, accurate prediction of location and timing of snow avalanches is so far not possible.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of slope stability with respect to snowpack spatial variability

Gaume¹,

Schweizer²,

Herwijnen³

et al. 2014

JGR Earth Surface

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The evaluation of avalanche release conditions constitutes a great challenge for risk assessment in mountainous areas. The spatial variability of snowpack properties has an important impact on snow slope stability and thus on avalanche formation, since it strongly influences failure initiation and crack propagation in weak snow layers. Hence, the determination of the link between these spatial variations and slope stability is very important, in particular, for avalanche public forecasting. In this study, a statistical-mechanical model of the slab-weak layer (WL) system relying on stochastic finite element simulations is used to investigate snowpack stability and avalanche release probability for spontaneously releasing avalanches. This model accounts, in particular, for the spatial variations of WL shear strength and stress redistribution by elasticity of the slab. We show how avalanche release probability can be computed from release depth distributions, which allows us to study the influence of WL spatial variations and slab properties on slope stability. The importance of smoothing effects by slab elasticity is verified and the crucial impact of spatial variation characteristics on the so-called knock-down effect on slope stability is revisited using this model. Finally, critical length values are computed from the simulations as a function of the various model parameters and are compared to field data obtained with propagation saw tests.

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“…The model thus provides no answers when studying the failure at the scale of snow particle aggregates. More comprehensive approaches must be employed for this type of investigation, such as, for example, McClung [1979McClung [ , 1981 or Louchet [2001]. The advantages of the present model with respect to comprehensive approaches are its simplicity, its requirement of field measurable input only (except for the elastic modulus, which can be estimated from density however) and its precise statements that can be tested in field experiments.…”

mentioning

confidence: 99%

Solitary fracture waves in metastable snow stratifications

Heierli¹

2005

J. Geophys. Res.

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[1] Fracture processes in layered snow have many implications on avalanche hazard and mountain safety. This paper is a contribution for a better understanding of fracture dynamics in a stratified medium with a collapsible layer in terms of a simple analytical model involving only field measurable parameters. For this purpose a simple three-layer snow stratification is considered to consist of a compact basal layer, a collapsible weak layer, and a homogenous top layer. It is shown analytically that the fracture of the weak layer can occur in the form of a localized disturbance zone propagating a collapse with constant velocity and wavelength. Simple analytical expressions describing the disturbance are obtained. The results are in good agreement with observations in the terrain. The presented fracture process is relevant to the release of dry snow slab avalanches and to the propagation of firn quakes and whumpfs but may also apply to other stratified media with appropriate properties.

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Shear fracture precipitated by strain softening as a mechanism of dry slab avalanche release

Cited by 132 publications

References 7 publications

Modeling of crack propagation in weak snowpack layers using the discrete element method

Modeling of crack propagation in weak snowpack layers using the discrete element method

Evaluation of slope stability with respect to snowpack spatial variability

Solitary fracture waves in metastable snow stratifications

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