Please note, due to essential maintenance online transactions will not be possible between 02:30 and 04:00 BST, on Tuesday 17th September 2019 (22:30-00:00 EDT, 17 Sep, 2019). We apologise for any inconvenience.
To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure email@example.com
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Snow slab avalanches primarily release by propagation of shear fractures within thin weak layers under thicker slabs. The weak layer is typically on the order of 1 mm thick and fails in mode II. In some cases, the weak layer is thicker and there may be a need to consider slope-normal deformation as part of the energy condition prior to rapid propagation. In this paper, field measurements from shear fracture initiation and high-speed films are combined to consider the effects of slope-normal deformation on bending of the slab prior to propagation and its relation to the propagation condition. Slab bending is modelled using two limiting cases: (1) a uniformly loaded beam supported by a deforming weak layer, analogous to a Winkler foundation, and (2) a uniformly loaded unsupported cantilevered beam. The experimental and analytical results suggest that slab bending prior to fracture initiation is small or negligible. Two previous approaches to modelling slab avalanche initiation involving slab bending are discussed. Both models proposed strong slab-bending effects prior to initiation, which conflicts with our results. Our field observations and modelling both show that strong bending is a dynamic effect following slope-parallel weak-layer fracture initiation.
A thin-blade snow hardness gauge was developed that measures penetration resistance over a length scale (on the order of 10–100 grain contacts) relevant to the fracture of slab avalanches. A thin blade was chosen to measure the ruptures of bonds and grain structures and minimize the effects of snow compaction during penetration. The apparatus consists of a 10 cm wide, 0.6 mm thick stainless-steel blade attached to a digital push–pull gauge. Blade penetration measurements are easy to conduct in the field and laboratory and required no post-processing or subjective interpretation. Measurements were conducted in snow pits to test the effects of penetration rate, blade orientation and blade width. The blade hardness index, defined as the maximum force of penetration, is a highly repeatable measure across observers compared to the hand hardness test. The blade hardness index was a better variable than the density for correlating with tensile strength measurements in a cold laboratory and with a cohesive strength measure in the field. As strength is one of the most important parameters in the fracture mechanics of slab avalanches, the strong correlation between thin-blade penetration and strength should benefit future slope stability evaluations using this gauge.
Email your librarian or administrator to recommend adding this to your organisation's collection.