Fracture propagation propensity in relation to snow slab avalanche release: Validating the Propagation Saw Test

Gauthier, David A.; Jamieson, Bruce

doi:10.1029/2008gl034245

Cited by 29 publications

(36 citation statements)

References 14 publications

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“…In other words, the false instability ratio for the PST in our results was 0% (Table 2). Gauthier and Jamieson (2008) report a false instability ratio of 5% for the 57 tests they conducted on stable slopes. Looking at ECT results reveals that the fracture propagated across the extended column completely in three cases, for a false instability ratio of about 9% (Table 2).…”

Section: Resultsmentioning

confidence: 97%

The Extended Column Test: Test effectiveness, spatial variability, and comparison with the Propagation Saw Test

Simenhois

Birkeland

2009

Cold Regions Science and Technology

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The Extended Column Test (ECT) is a new stability test that aims to assess the fracture propagation potential across a 90 cm wide isolated column. Initial results with a dataset consisting of over 300 tests collected by one observer demonstrated the ECT's effectiveness for differentiating between stable and unstable slopes. Further, we have received positive feedback on the test from a world-wide network of observers. This paper: 1) presents new recording standards for the test, 2) uses the SnowPilot dataset to further assess the effectiveness of the test by analyzing over 300 tests performed by several observers in different snow climates, 3) looks at the spatial variability of ECT results from several test grids, and 4) compares side-by-side results between the ECT and the Propagation Saw Test on stable and unstable slopes. Our results indicate that the ECT is an effective stability test, with a false stability ratio generally less than other standard snow stability tests. Results are sometimes quite spatially uniform, though occasionally slopes may exhibit variable ECT results. In comparison to the PST, our data suggest the ECT has a lower false stability rate, but a higher false instability rate. No test is perfect and all tests must be used in conjunction with additional data, but our results show the ECT is valuable additional tool for assessing snow stability.

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Section: Resultsmentioning

confidence: 97%

The Extended Column Test: Test effectiveness, spatial variability, and comparison with the Propagation Saw Test

Simenhois

Birkeland

2009

Cold Regions Science and Technology

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“…Our laboratory experiments are related to failure initiation as we study the development of the initial crack needed for fracture propagation. To study fracture propagation field tests with large samples are needed, such as the propagation saw test developed by Gauthier and Jamieson [2008] and Sigrist and Schweizer [2007].…”

Section: Discussionmentioning

confidence: 99%

Failure of a layer of buried surface hoar

Reiweger¹,

Schweizer²

2010

Geophysical Research Letters

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[1] In order to study the formation of the initial failure leading to dry-snow slab avalanche release, we performed loading experiments in a cold laboratory with natural samples including a layer of buried surface hoar. The experimental setup was such that the layered snow samples were loaded continuously for various tilt (slope) angles; loading rates varied between 1 and 20 Pa s −1 . The stress at fracture decreased with increasing loading rate and increasing slope angle, i.e., increasing shear component of the load. The latter result means that the layer was stronger in compression than in shear which is attributed to the particularly anisotropic nature of layers of buried surface hoar. Particle image velocimetry revealed that almost 90% of the sample's global deformation was concentrated in the weak layer. For avalanche release our results imply that the shear component of deformation is of particular importance for failure initiation.

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“…PST experiments to study propagating cracks have confirmed deformation of the slab to substantially contribute to the mechanical energy consumed by crack extension (van Herwijnen et al, 2010). Further, Gauthier and Jamieson (2008b) have shown that the critical crack length together with the fracture result are related to slope instability. In particular, cracks propagating to the end of the column after saw cut lengths less than 50 % of the column length were clear indicators of high crack propagation propensity.…”

Section: Introductionmentioning

confidence: 98%

A process-based approach to estimate point snow instability

Reuter¹,

Schweizer²,

Herwijnen³

2015

The Cryosphere

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Abstract. Snow instability data provide information about the mechanical state of the snow cover and are essential for forecasting snow avalanches. So far, direct observations of instability (recent avalanches, shooting cracks or whumpf sounds) are complemented with field tests such as the rutschblock test, since no measurement method for instability exists. We propose a new approach based on snow mechanical properties derived from the snow micropenetrometer that takes into account the two essential processes during dry-snow avalanche release: failure initiation and crack propagation. To estimate the propensity of failure initiation we define a stress-based failure criterion, whereas the propensity of crack propagation is described by the critical cut length as obtained with a propagation saw test. The input parameters include layer thickness, snow density, effective elastic modulus, strength and specific fracture energy of the weak layer -all derived from the penetration-force signal acquired with the snow micro-penetrometer. Both instability measures were validated with independent field data and correlated well with results from field tests. Comparisons with observed signs of instability clearly indicated that a snowpack is only prone to avalanche if the two separate conditions for failure initiation and crack propagation are fulfilled. To our knowledge, this is the first time that an objective method for estimating snow instability has been proposed. The approach can either be used directly based on field measurements with the snow micro-penetrometer, or be implemented in numerical snow cover models. With an objective measure of instability at hand, the problem of spatial variations of instability and its causes can now be tackled.

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Fracture propagation propensity in relation to snow slab avalanche release: Validating the Propagation Saw Test

Cited by 29 publications

References 14 publications

The Extended Column Test: Test effectiveness, spatial variability, and comparison with the Propagation Saw Test

The Extended Column Test: Test effectiveness, spatial variability, and comparison with the Propagation Saw Test

Failure of a layer of buried surface hoar

A process-based approach to estimate point snow instability

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