Determination of failure envelope for faceted snow through numerical simulations

Chandel, Chaman; Srivastava, P. K.; Mahajan, Puneet

doi:10.1016/j.coldregions.2015.04.009

Cited by 14 publications

(8 citation statements)

References 36 publications

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“…We recall the main characteristics of the three key components. On the basis of laboratory experiments (Reiweger et al, 2015) and simulations based on Xray computed tomography (Hagenmuller et al, 2015;Chandel et al, 2015;Srivastava et al, 2017), the yield surface is defined in the space of the p-q invariants of the stress tensor as follows:…”

Section: Finite-strain Elastoplastic Modelmentioning

confidence: 99%

The mechanical origin of snow avalanche dynamics and flow regime transitions

Sovilla²,

Jiang

et al. 2020

The Cryosphere

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Abstract. Snow avalanches cause fatalities and economic damage. Key to their mitigation is the understanding of snow avalanche dynamics. This study investigates the dynamic behavior of snow avalanches, using the material point method (MPM) and an elastoplastic constitutive law for porous cohesive materials. By virtue of the hybrid Eulerian–Lagrangian nature of the MPM, we can handle processes involving large deformations, collisions and fractures. Meanwhile, the elastoplastic model enables us to capture the mixed-mode failure of snow, including tensile, shear and compressive failure. Using the proposed numerical approach, distinct behaviors of snow avalanches, from fluid-like to solid-like, are examined with varied snow mechanical properties. In particular, four flow regimes reported from real observations are identified, namely, cold dense, warm shear, warm plug and sliding slab regimes. Moreover, notable surges and roll waves are observed peculiarly for flows in transition from cold dense to warm shear regimes. Each of the flow regimes shows unique flow characteristics in terms of the evolution of the avalanche front, the free-surface shape, and the vertical velocity profile. We further explore the influence of slope geometry on the behavior of snow avalanches, including the effect of slope angle and path length on the maximum flow velocity, the runout angle and the deposit height. Unified trends are obtained between the normalized maximum flow velocity and the scaled runout angle as well as the scaled deposit height, reflecting analogous rules with different geometry conditions of the slope. It is found that the maximum flow velocity is mainly controlled by the friction between the bed and the flow, the geometry of the slope, and the snow properties. We reveal the crucial effect of both flow and deposition behaviors on the runout angle. Furthermore, our MPM modeling is calibrated and tested with simulations of real snow avalanches. The evolution of the avalanche front position and velocity from the MPM modeling shows reasonable agreement with the measurement data from the literature. The MPM approach serves as a novel and promising tool to offer systematic and quantitative analysis for mitigation of gravitational hazards like snow avalanches.

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Section: Finite-strain Elastoplastic Modelmentioning

confidence: 99%

The mechanical origin of snow avalanche dynamics and flow regime transitions

Sovilla²,

Jiang

et al. 2020

The Cryosphere

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“…Under this model, failure is predicted to occur only for slope angles larger than the angle of internal friction, typically above . More recently, the possible compressive failure of snow reported in laboratory experiments [ 5 , 25 , 35 ] was accounted for by including a compressive cap in the classical MC model leading to the so-called Mohr–Coulomb-Cap (MCC) model [ 25 ]. Despite a better understanding of snow mixed-mode failure, its micromechanical features (localized or diffuse failure [ 22 ]) are still not fully understood.…”

Section: Introductionmentioning

confidence: 99%

Numerical investigation of the mixed-mode failure of snow

Mulak

Gaume

2019

Comp. Part. Mech.

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The failure of a weak snow layer underlying a cohesive slab is the primary step in the release process of a dry snow slab avalanche. The complex and heterogeneous microstructure of snow limits our understanding of failure initiation inside the weak layer, especially under mixed-mode shear–compression loading. Further complication arises from the dependence of snow strength on the loading rate induced by the balance between bond breaking and bond formation (sintering) during the failure process. Here, we use the discrete element method to investigate the influence of mixed-mode loading and fast sintering on the failure of a weak layer generated using cohesive ballistic deposition. Both fast and slow loading simulations resulted in a mixed-mode failure envelope in good agreement with laboratory experiments. We show that the number of broken bonds at failure and the weak layer strength significantly decreases with increasing loading angle, regardless of the loading rate. While the influence of loading rate appears negligible in shear-dominant loading (for loading angles above ), simulations suggest a significant increase in the weak layer strength at low loading angles and low loading rates, characteristic of natural avalanches, due to the presence of an active sintering mechanism.

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“…However, for large values of σ , snow can exhibit compressive failures leading to a decrease of the shear strength with increasing σ . Furthermore, Chandel et al () described weak layers for which the shear strength always decreases with increasing σ . These discrepancies reveal the strong variability of weak snow layers, such that there is probably no unique failure criterion describing all types of weak layers.…”

Section: Discussionmentioning

confidence: 99%

“…However, Reiweger et al (2015) and Chandel et al (2015) showed that the shear strength of weak snow layers may also decrease for larger values of (closed failure envelope). Hence, the dependence with slope angle was also tested for two other simple failure criteria represented in Figure 4 (inset), one in which the shear strength p is independent of the normal stress and one for which p decreases with increasing :…”

Section: Condition For the Onset Of Crack Propagationmentioning

confidence: 99%

“…A dry-snow slab avalanche originates due to the initiation of a failure in a weak snow layer buried below a cohesive slab, followed by the onset of rapid crack propagation within the weak layer (McClung, 1979;Schweizer et al, 2003;Schweizer, Reuter, van Herwijnen, Richter, & Gaume, 2016). Our understanding of failure initiation has greatly improved over the last decade, in particular, thanks to laboratory and field experiments on snow failure (Chandel et al, 2015;Reiweger & Schweizer, 2010). Recently, Reiweger et al (2015) characterized the failure envelope of different types of weak layers under mixed-mode loading.…”

Section: Introductionmentioning

confidence: 99%

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Stress Concentrations in Weak Snowpack Layers and Conditions for Slab Avalanche Release

Gaume

Chambon

Herwijnen³

et al. 2018

Geophysical Research Letters

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Dry‐snow slab avalanches release due to the formation of a crack in a weak layer buried below cohesive snow slabs, followed by rapid crack propagation. The onset of rapid crack propagation occurs if stresses at the crack tip in the weak layer overcome its strength. In this study, we use the finite element method to evaluate the maximum shear stress τmax induced by a preexisting crack in a weak snow layer allowing for the bending of the overlaying slab. It is shown that τmax increases with increasing crack length, slab thickness, slab density, weak layer elastic modulus, and slope angle. In contrast, τmax decreases with increasing elastic modulus of the slab. Assuming a realistic failure envelope, we computed the critical crack length ac for the onset of crack propagation. The model allows for remote triggering from flat (or low angle) terrain. Yet it shows that the critical crack length decreases with increasing slope angle.

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Determination of failure envelope for faceted snow through numerical simulations

Cited by 14 publications

References 36 publications

The mechanical origin of snow avalanche dynamics and flow regime transitions

The mechanical origin of snow avalanche dynamics and flow regime transitions

Numerical investigation of the mixed-mode failure of snow

Stress Concentrations in Weak Snowpack Layers and Conditions for Slab Avalanche Release

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