Healing of snow surface-to-surface contacts by isothermal sintering

Podolskiy, Evgeny A.; Barbero, Monica; Barpi, Fabrizio; Chambon, Guillaume; Brunetto, Mauro Borri; Pallara, Oronzo Vito; Frigo, Barbara; Chiaia, Bernardino; Naaïm, Mohamed

doi:10.5194/tc-8-1651-2014

Cited by 20 publications

(19 citation statements)

References 25 publications

(51 reference statements)

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“…However, these PST experiments were performed on a nonpersistent WL consisting of precipitation particles and measurements made on the flat were performed 1 day before the experiments made on slopes (Gauthier, 2007). This indicates that the trend with slope angle may be influenced by the burial time of the WL since sintering and settlement effects can strongly affect snowpack properties within 1 day, especially with the layer of precipitation particles which was tested (Szabo and Schneebeli, 2007;van Herwijnen and Miller, 2013;Podolskiy et al, 2014). Furthermore, Heierli et al (2008) assumed snow cover properties independent of slope angle, which is somewhat questionable since snowpack properties can also change with slope angle, thus obscuring the true slope angle influence.…”

Section: Comparison With the Anticrack Modelmentioning

confidence: 96%

Snow fracture in relation to slab avalanche release: critical state for the onset of crack propagation

Gaume

Herwijnen²,

Chambon

et al. 2017

The Cryosphere

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Abstract. The failure of a weak snow layer buried below cohesive slab layers is a necessary, but insufficient, condition for the release of a dry-snow slab avalanche. The size of the crack in the weak layer must also exceed a critical length to propagate across a slope. In contrast to pioneering shear-based approaches, recent developments account for weak layer collapse and allow for better explaining typical observations of remote triggering from low-angle terrain. However, these new models predict a critical length for crack propagation that is almost independent of slope angle, a rather surprising and counterintuitive result. Based on discrete element simulations we propose a new analytical expression for the critical crack length. This new model reconciles past approaches by considering for the first time the complex interplay between slab elasticity and the mechanical behavior of the weak layer including its structural collapse. The crack begins to propagate when the stress induced by slab loading and deformation at the crack tip exceeds the limit given by the failure envelope of the weak layer. The model can reproduce crack propagation on low-angle terrain and the decrease in critical length with increasing slope angle as modeled in numerical experiments. The good agreement of our new model with extensive field data and the ease of implementation in the snow cover model SNOWPACK opens a promising prospect for improving avalanche forecasting.

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Section: Comparison With the Anticrack Modelmentioning

confidence: 96%

Snow fracture in relation to slab avalanche release: critical state for the onset of crack propagation

Gaume

Herwijnen²,

Chambon

et al. 2017

The Cryosphere

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“…However, for the experiments, the critical length generally increases with increasing density due to the settlement which induces an increase of Young's modulus and a strengthening of the WL (Zeidler and Jamieson, 2006a, b;Szabo and Schneebeli, 2007;Podolskiy et al, 2014). In contrast, for case #1, a decrease in slab thickness and slope angle induces a decrease in the crack propagation speed (Fig.…”

Section: Crack Propagation Speedmentioning

confidence: 96%

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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“…So the effect of using different initial conditions in the simulation remains to be addressed in the future. Furthermore, the time-dependence of the sintering force and the strength as observed in Szabo and Schneebeli [2007] and Podolskiy et al [2014] as well as densification effects are not accounted for in our model, but might affect the persistency and the strength of the granules. To further constrain the parameters of the model, the visco-elastic properties of the granules and the strength of the bonds needs to be known.…”

Section: Discussionmentioning

confidence: 99%

“…Our model simpler but also more straightforward to apply to snow. Its model parameters, namely the tensile strength and the sintering force, can be evaluated from laboratory experiments such as tension [Hagenmuller et al, 2014;Sigrist, 2006] and sintering [Podolskiy et al, 2014;Szabo and Schneebeli, 2007] tests.…”

Section: Methodsmentioning

confidence: 99%