Numerical simulation of microstructural damage and tensile strength of snow

Hagenmuller, Pascal; Theile, T.; Schneebeli, Martin

doi:10.1002/2013gl058078

Cited by 46 publications

(49 citation statements)

References 23 publications

(24 reference statements)

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“…In the future, the micro-structure of the WL could be derived from microtomographic images (Hagenmuller et al, 2014) in order to perform more realistic simulations. In addition, whereas we applied our model for cases for which the bending of the slab is important, our approach could still be used for cases with thinner weak layers and thus much lower height of bending.…”

Section: Discussionmentioning

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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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: Discussionmentioning

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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“…While grain rearrangements cannot be considered without the use of mesh adaptation techniques, the deformation of the ice skeleton is explicitly taken into account, which is of primary importance as long as the topology of the ice skeleton is preserved. In the last decade, many studies addressed in details the case of elasticity (Schneebeli, 2004;Pieritz et al, 2004;Srivastava et al, 2010;Köchle and Schneebeli, 2014;Wautier et al, 2015;Srivastava et al, 2016), possibly up to a brittle failure (Hagenmuller et al, 2014), whereas more complex types of constitutive behavior were hardly ever considered. To the best of our knowledge, no general viscoplastic constitutive equation for snow can be found in the literature.…”

Section: Introductionmentioning

confidence: 99%

Numerical homogenization of the viscoplastic behavior of snow based on X-ray tomography images

2017

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Abstract. While the homogenization of snow elastic properties has been widely reported in the literature, homogeneous rate-dependent behavior responsible for the densification of the snowpack has hardly ever been upscaled from snow microstructure. We therefore adapt homogenization techniques developed within the framework of elasticity to the study of snow viscoplastic behavior. Based on the definition of kinematically uniform boundary conditions, homogenization problems are applied to 3-D images obtained from X-ray tomography, and the mechanical response of snow samples is explored for several densities. We propose an original postprocessing approach in terms of viscous dissipated powers in order to formulate snow macroscopic behavior. Then, we show that Abouaf models are able to capture snow viscoplastic behavior and we formulate a homogenized constitutive equation based on a density parametrization. Eventually, we demonstrate the ability of the proposed models to account for the macroscopic mechanical response of snow for classical laboratory tests.

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“…In contrast, in this study, density appears to be a very good indicator of the resistance of snow under compression, with only a little scatter attributable to the snow type. In other microstructure-based models, a similar strong dependence on density was also observed for thermal conductivity (Calonne et al, 2011), tensile strength (Hagenmuller et al, 2014c) or the Young's modulus (Kochle and Schneebeli, 2014). The main difference between the microstructure-based simulations and direct experimental measurements is the size of the volume tested.…”

Section: Influence Of Density and Microstructure On The Mechanical Bementioning

confidence: 53%

“…2.3.2), the strain interval for the elastic phase is overestimated. In real snow, irreversible damage starts to occur for smaller strains of about 10 −4 (Hagenmuller et al, 2014c).…”

Section: Elastic Phasementioning

confidence: 99%

“…With micro-computed tomography (µCT), it is now possible to obtain a 3-D image of the microstructure at resolutions down to a few microns (Brzoska et al, 1999;Coléou et al, 2001;Schneebeli and Sokratov, 2004). The images obtained can be used as direct input for mechanical simulations (Schneebeli, 2004;Srivastava et al, 2010;Hagenmuller et al, 2014c;Chandel et al, 2014). These µCT-based mechanical models nevertheless tend to be computationally extremely expensive, especially when the microstructure is meshed with finite elements (FE) of similar sizes and no degree of freedom is blocked.…”

Section: Introductionmentioning

confidence: 99%

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Microstructure-based modeling of snow mechanics: a discrete element approach

2015

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Abstract. Rapid and large deformations of snow are mainly controlled by grain rearrangements, which occur through the failure of cohesive bonds and the creation of new contacts. We exploit a granular description of snow to develop a discrete element model based on the full 3-D microstructure captured by microtomography. The model assumes that snow is composed of rigid grains interacting through localized contacts accounting for cohesion and friction. The geometry of the grains and of the intergranular bonding system are explicitly defined from microtomographic data using geometrical criteria based on curvature and contiguity. Single grains are represented as rigid clumps of spheres. The model is applied to different snow samples subjected to confined compression tests. A detailed sensitivity analysis shows that artifacts introduced by the modeling approach and the influence of numerical parameters are limited compared to variations due to the geometry of the microstructure. The model shows that the compression behavior of snow is mainly controlled by the density of the samples, but that deviations from a pure density parameterization are not insignificant during the first phase of deformation. In particular, the model correctly predicts that, for a given density, faceted crystals are less resistant to compression than rounded grains or decomposed snow. For larger compression strains, no clear differences between snow types are observed.

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Numerical simulation of microstructural damage and tensile strength of snow

Cited by 46 publications

References 23 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

Numerical homogenization of the viscoplastic behavior of snow based on X-ray tomography images

Microstructure-based modeling of snow mechanics: a discrete element approach

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