Year: 2016
Type: conference-paper
Abstract: Our understanding of dry-snow slab avalanche release improved over the last decade -\nnot the least by consistently following a fracture mechanical approach. Whether we consider artificial triggering\nor natural release, slab avalanches result from a sequence of fracture processes including (i) failure\ninitiation in a weak layer underlying a cohesive snow slab, (ii) the onset of crack propagation, (iii) dynamic\ncrack propagation through the weak layer across the slope, and (iv) tensile failure – equivalent to\ncrack arrest, followed by sliding of the slab. While failure initiation is best understood in terms of applied\nstress and strength, crack propagation is best understood in terms of stress intensity and fracture toughness.\nThe typical anisotropic microstructure of persistent weak layers favors failure in shear rather than\ncompression under mixed-mode loading - though the failure type at the micro-scale is largely unknown\ndue the complex stress state in the ice matrix. The fracture mechanical approach has also changed our\nview on the spatially variable nature of the snow cover. Spatial variations of weak layer as well as slab\nproperties may control avalanche formation, since disorder is fundamental for the fracture process. For\nexample, failures will initiate from locally weaker spots, and fractures may arrest due to locally stronger\nareas. Whereas we still lack a comprehensive model linking damage at the micro-scale to avalanche size,\nrecent modelling approaches have demonstrated - by assuming realistic failure behavior of the weak\nlayer including its collapse and resulting mixed stress states in the slab layers - that not only failure initiation,\nbut also crack propagation depends on slope angle. We present a modern synthesis of avalanche\nrelease.
Language: English
Subfield: Management, Monitoring, Policy and Law
Field: Environmental Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2616485961