Mechanics of weak layer snow under cyclic loading studied by FEM
Résumé
The mechanical behavior of snow weak layers is a crucial element in dry snow slab avalanche forecasting. Here, we use Finite Element Method (FEM) modeling to investigate the mechanics of layered snow under cyclic loading at a high acceleration rate with gradually increasing amplitudes of stresses leading to fracture. The provided 2-D model is based on the 'Cast3M' code. It treats the weak layer as an interface with variable constitutive behavior parameters (an approach which was initially developed for rock joints). The applicability of the proposed model is evaluated against the previous cold laboratory snow fracture experiments of Podolskiy et al. (2010) (shaking table tests studying the dynamic response of weak layer snow samples). Results: (i) show that joints with no tensional strength (as used in some previous studies) are not capable of reproducing the experiments; (ii) suggest that the Mohr- Coulomb failure criterion (controlled by tension strength and angle of friction) is sufficient to describe experiments; and (iii) highlight the complexity of strain and stress evolution within snow samples, and especially the significance of tension at the edges of the weak layer. Our simulations demonstrate that the analytical solution, based on Newton's second law (Nakamura et al., 2010; Podolskiy et al., 2010), may underestimate real shear stresses due to inertial effects. Hence, modeling allows refining the experimental data and provides reliable estimates of weak layer mechanical properties.
Domaines
Sciences de l'environnement
Origine : Fichiers produits par l'(les) auteur(s)
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