Item: Using High-Speed Video to Better Understand Extended Column Tests
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Title: Using High-Speed Video to Better Understand Extended Column Tests
Proceedings: Proceedings, 2012 International Snow Science Workshop, Anchorage, Alaska
Authors:
- Karl W. Birkeland [ USDA Forest Service National Avalanche Center, Bozeman, Montana, USA ]
- Alec van Herwijnen [ WSL Swiss Federal Institute for Snow and Avalanche Research SLF , Davos, Switzerland ]
Date: 2012
Abstract: Extended Column Tests (ECTs) have become increasingly popular for assessing snowpack stability. However, we still do not fully understand what happens to the block and the underlying weak layer during the test. Such work has been done for the Propagation Saw Test (PST), but not for the ECT. In order to better understand and interpret ECT results, we analyzed high-speed video (240 frames/second) of propagating ECTs using particle tracking. Our results show several things: 1) fractures initiate in an area of the weak layer directly under the shovel at the free edge of the block, 2) at the resolution of our measurements we do not see signs of progressive damage accumulation in the weak layer during tapping, but rather a single rapid collapse when fracture is initiated, 3) tapping on one side of the ECT does not affect the far side of the ECT, and 4) measured fracture speeds are similar to previously reported values, including those measured using the PST. From a practical perspective, our results suggest that the ECT is indeed measuring the propensity of a crack to propagate at the small scale of the ECT block, giving us greater confidence that we are capturing a critically important property of snow stability in our tests.
Object ID: issw-2012-098-103.pdf
Language of Article: English
Presenter(s): unknown
Keywords: extended column test, propagation saw test, snowpack stability test,
Page Number(s): 98-103
Subjects: snowpack stability Extended Column Test (ECT) propagation saw test
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