Item: What Do Longer Tests Tell Us About Fracture and Stability?
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Title: What Do Longer Tests Tell Us About Fracture and Stability?
Proceedings: International Snow Science Workshop 2014 Proceedings, Banff, Canada
Authors:
- Edward H. Bair [ Earth Research Institute, University of California, Santa Barbara, CA, USA ]
- Ron Simenhois [ Southeast Alaska Avalanche Center, Juneau, AK, USA ]
- Alec van Herwijnen [ WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland ]
- Karl Birkeland [ US Forest Service National Avalanche Center, Bozeman, MT, USA ]
Date: 2014-09-29
Abstract: Extended Column Tests (ECT) and Propagation Saw Tests (PST) are used to assess crack propagation; that is, the likelihood of a crack self-propagating. Yet, we present findings that show that full crack propagation to the end of the beam depends on beam length. The practical question is: are beams about 1 m long optimal for assessing stability? Finite element modeling shows that the so called "far edge attraction" becomes insignificant for beams longer than 2 m. In other words, full crack propagation becomes independent of beam length when beams ≥ 2 m are used. To test the accuracy of 2 m tests for stability evaluation, we collected data on 135 side-by-side standard length ECTPs (full propagation) followed by 2 m ECTs. We only focused on ECTPs because we assumed 2 m ECTs would not propagate if standard length tests did not. These tests were preceded by an a priori stability assessment to reduce circularity or stability ratings based on test results. Our results show that the proportion of tests in agreement, i.e. ECTP and 2 m ECTP, increase with decreasing stability. We conclude that an ECTP followed by a 2 m ECTP is a clear red flag. The interpretation of an ECTP followed by a 2 m ECTN/X (no propagation) is not clear. The main finding for practitioners is that a 2 m ECT can be used to give additional information about slope stability following an ECTP.
Object ID: ISSW14_paper_O7.03.pdf
Language of Article: English
Presenter(s):
Keywords: stability tests, Extended Column Test, Propagation Saw Test, fracture.
Page Number(s): 185-190
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