A grain-size driven transition in the deformation mechanism in slow snow compression

Sundu, Kavitha; Ottersberg, Rafael; Jaggi, Matthias; Löwe, Henning

doi:10.1016/j.actamat.2023.119359

Cited by 3 publications

(3 citation statements)

References 52 publications

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“…This is attributed to the ability to relax strain incompatibilities at ice/air interfaces. The residual mismatch between the measured and the simulated viscosity tends to demonstrate that other mechanisms occurring, for example, at bonds need to be accounted for, such as, role of non‐basal contributions with hardening (Duval et al., 1983a; Suquet et al., 2012), superplasticity (Alley, 1987; Goldsby & Kohlstedt, 2001; Raj & Ashby, 1971; Sundu et al., 2024), but also ductile failure (Capelli et al., 2020; Kirchner et al., 2001).…”

Section: Discussionmentioning

confidence: 99%

“…However, the geometrical microstructure alone appears insufficient to describe the diverse creep rates observed on different snow types (Calonne et al., 2020; Fourteau et al., 2022). Besides, the driving deformation mechanism at the microscale, either inter‐crystalline deformation (e.g., grain boundary sliding) or intra‐crystalline deformation, remains a matter of debate because of a lack of experimental evidence (Meyssonnier et al., 2009a; Sundu et al., 2024; Theile et al., 2011).…”

Section: Introductionmentioning

confidence: 99%

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Role of Ice Mechanics on Snow Viscoplasticity

Védrine,

Hagenmuller,

Gélébart

et al. 2024

Geophysical Research Letters

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The porous structure of snow becomes denser with time under gravity, primarily due to the creep of its ice matrix with viscoplasticity. Despite investigation of this behavior at the macroscopic scale, the driving microscopic mechanisms are still not well understood. Thanks to high‐performance computing and dedicated solvers, we modeled snow elasto‐viscoplasticity with 3D images of its microstructure and different mechanical models of ice. The comparison of our numerical experiments to oedometric compression tests measured by tomography showed that ice in snow rather behaves as a heterogeneous set of ice crystals than as homogeneous polycrystalline ice. Similarly to dense ice, the basal slip system contributed at most, in the simulations, to the total snow deformation. However, in the model, the deformation accommodation between crystals was permitted by the pore space and did not require any prismatic and pyramidal slips, whereas the latter are pre‐requisite for the simulation of dense ice.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Role of Ice Mechanics on Snow Viscoplasticity

Védrine,

Hagenmuller,

Gélébart

et al. 2024

Geophysical Research Letters

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“…In addition, changes in snow cover intensity are strongly influenced by factors such as the degree of binding between snow particles, temperature, and crystal size [60]. Sundu et al (2024) repeatedly compressed snow blocks through load relaxation cycles, considering different types and relative densities of snow samples, as well as changes in geometric grain size, and revealed for the first time that the apparent change in the stress index in snow is driven by (geometric) grain size [61]. Ishiguro (2017) considered the influence caused by different contact surfaces when the snow block was compressed by loads and sequentially selected cylindrical, square, and rectangular cross-sectional pressure vessels to carry out the snow block compression experiment [62].…”

Section: Snow Failure In Compressionmentioning

confidence: 99%

Antarctic Snow Failure Mechanics: Analysis, Simulations, and Applications

Xiao,

Li,

Matin Nazar

et al. 2024

Materials

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Snow failure is the process by which the stability of snow or snow-covered slopes is destroyed, resulting in the collapse or release of snow. Heavy snowfall, low temperatures, and volatile weather typically cause consequences in Antarctica, which can occur at different scales, from small, localized collapses to massive avalanches, and result in significant risk to human activities and infrastructures. Understanding snow damage is critical to assessing potential hazards associated with snow-covered terrain and implementing effective risk mitigation strategies. This review discusses the theoretical models and numerical simulation methods commonly used in Antarctic snow failure research. We focus on the various theoretical models proposed in the literature, including the fiber bundle model (FBM), discrete element model (DEM), cellular automata (CA) model, and continuous cavity-expansion penetration (CCEP) model. In addition, we overview some methods to acquire the three-dimensional solid models and the related advantages and disadvantages. Then, we discuss some critical numerical techniques used to simulate the snow failure process, such as the finite element method (FEM) and three-dimensional (3D) material point method (MPM), highlighting their features in capturing the complex behavior of snow failure. Eventually, different case studies and the experimental validation of these models and simulation methods in the context of Antarctic snow failure are presented, as well as the application of snow failure research to facility construction. This review provides a comprehensive analysis of snow properties, essential numerical simulation methods, and related applications to enhance our understanding of Antarctic snow failure, which offer valuable resources for designing and managing potential infrastructure in Antarctica.

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Microstructure-based simulations of the viscous densification of snow and firn

Fourteau,

Freitag,

Malinen

et al. 2024

The Cryosphere

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Abstract. Accurate models for the viscous densification of snow (understood here as a density below 550 kg m−3) and firn (a density above 550 kg m−3) under mechanical stress are of primary importance for various applications, including avalanche prediction and the interpretation of ice cores. Formulations of snow and firn compaction in models are still largely empirical instead of using microstructures from micro-computed tomography to numerically compute the mechanical behavior directly from the physics at the microscale. The main difficulty of the latter approach is the choice of the correct rheology/constitutive law governing the deformation of the ice matrix, which is still controversially discussed. Being aware of these uncertainties, we conducted a first systematic attempt of microstructure-based modeling of snow and firn compaction. We employed the finite element suite Elmer FEM using snow and firn microstructures from different sites in the Alps and Antarctica to explore which ice rheologies are able to reproduce observations. We thereby extended the ParStokes solver in Elmer FEM to facilitate parallel computing of transverse isotropic material laws for monocrystalline ice. We found that firn densification can be reasonably well simulated across different sites assuming a polycrystalline rheology (Glen's law) that is traditionally used in glacier or ice sheet modeling. In contrast, for snow, the observations are in contradiction with this rheology. To further comprehend this finding, we conducted a sensitivity study on different ice rheologies. None of the material models is able to explain the observed high compactive viscosity of depth hoar compared to rounded grains having the same density. While, on one hand, our results re-emphasize the limitations of our current mechanical understanding of the ice in snow, they constitute, on the other hand, a confirmation of the common picture of firn as a foam of polycrystalline ice through microstructure-based simulations.

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A grain-size driven transition in the deformation mechanism in slow snow compression

Cited by 3 publications

References 52 publications

Role of Ice Mechanics on Snow Viscoplasticity

Role of Ice Mechanics on Snow Viscoplasticity

Antarctic Snow Failure Mechanics: Analysis, Simulations, and Applications

Microstructure-based simulations of the viscous densification of snow and firn

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