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| Titel |
The influence of edge effects on crack propagation in snow stability tests |
| VerfasserIn |
E. H. Bair, R. Simenhois, A. van Herwijnen, K. Birkeland |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1994-0416
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| Digitales Dokument |
URL |
| Erschienen |
In: The Cryosphere ; 8, no. 4 ; Nr. 8, no. 4 (2014-08-05), S.1407-1418 |
| Datensatznummer |
250116256
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| Publikation (Nr.) |
 copernicus.org/tc-8-1407-2014.pdf |
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| Zusammenfassung |
| The Extended Column Test (ECT) and the Propagation Saw Test (PST)
are two commonly used tests to assess the likelihood of crack propagation in
a snowpack. Guidelines suggest beams with lengths of around 1 m, yet little is
known about how test length affects propagation. Thus, we performed 163 ECTs
and PSTs 1.0–10.0 m long. On days with full crack propagation in 1.0–1.5 m
tests, we then made videos of tests 2.0–10.0 m long. We inserted markers
for particle tracking to measure collapse amplitude, propagation speed, and
wavelength. We also used a finite element (FE) model to simulate the strain
energy release rate at fixed crack lengths. We find that (1) the proportion
of tests with full propagation decreased with test length; (2) collapse was
greater at the ends of the beams than in the centers; (3) collapse amplitude
was independent of beam length and did not reach a constant value; (4)
collapse wavelengths in the longer tests were around 3 m, two times greater than
what is predicted by the anticrack model. We also confirmed the prediction
that centered PSTs had double the critical length of edge PSTs. Based on our
results, we conclude that cracks propagated more frequently in the shorter
tests because of increased stress concentration from the far edge. The FE
model suggests this edge effect occurs for PSTs of up to 2 m long or a crack to
beam length ratio ≥ 0.20. Our results suggest that ECT and PST length
guidelines may need to be revisited. |
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