Weak-layer spatial variability as a possible trigger of slab tensile failure
2013
Gaume, J. | Chambon, Guillaume | Eckert, N. | Naaim, M.
The evaluation of the location of slab tensile failure represents an important concern for the evaluation of the extent of avalanche release zones and hence hazard assessment. In this study, a mechanically-based statistical model of the slab-weak layer system accounting for weak-layer spatial variability, stress redistributions by elasticity of the slab and the slab possible tensile failure is simulated using a stochastic finite element method. Two types of avalanche releases are distinguished in the simulations: (1) full slope releases, for which the entire simulated slope is released and the heterogeneity is not sufficient to trigger a tensile failure within the slab; (2) partial slope releases, for which tensile failure occurs within the slab due to the heterogeneity so that only a part of the slope is released. We present the proportion of these two release types as a function of the different model parameters obtained from finite element simulations. One of the main outcomes is that, for slab tensile strength higher than the average cohesion of the weak layer, all the releases appear to be full-slope, justifying the major influence of topographical and morphological features such as rocks, trees, slope curvature, ridge and heterogeneous snow cover often claimed in the literature.
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