Snow Cornice Development and Failure Monitoring
Notice bibliographique
Résumé
Snow cornices are significant winter alpine and snow avalanche hazards. A cornice is a leeward growing mass of snow overhanging from a ridge or sharp break in slope (perpendicular to the ridgeline) due to windblown snow (Seligman, 1936). A cornice’s usual topographic position and cantilevered slab structure, regularly above large avalanche prone slopes, makes cornices crucial to consider from a risk perspective. Although cornices are extensively controlled in avalanche operations, they have been given little attention in science. Only basic work has been done on their formation, development, structure and control, with limited focus and geographic extent (Kobayashi, 1988, McCarty et al., 1986, McClung and Schaerer, 1993, Montagne et al., 1968). Although significant work has been done on snow slab fracture mechanics, no work has been done on cornice failure and fracture mechanics. Three meteorologically-related triggers of cornice failure have been recognized: 1. Snow loading of the cornice overhang during storm and wind events; 2. abrupt temperature changes at the surfaces of the cornice due to a) abrupt warming or cooling air temperatures, b) rain-on-snow events, c) heating by solar radiation; and 3. seasonal warming/prolonged midwinter warm periods. Failure from snow loading results when newly fallen or wind-blown snow accumulates on the cornice overhang at a rate that induces stresses that exceed the strength/fracture toughness of the cornice. Creep fracture is thought to be the primary mechanism for failure of this type. Rain-on-snow events (and the concurrent abrupt warming) on dry snow slabs are shown to immediately increase the creep rate in the surface layer of the snow slab resulting in decreased slab stability (Conway, 1998). This immediate effect may similarly influence cornice stability, as well as the delayed time effects of increased loading from rainfall and weakening due to longer-term warming. Abrupt changes in air temperature alone are thought to be a trigger of dry snow slab avalanches (McClung, 1996). Further circumstantial and anecdotal evidence suggests that cooling and warming of the snow surface from abrupt changes in air temperature and heating from solar radiation initiate slab avalanches and cornice failures. I intend to monitor the development, physical properties (dimensions/geometry, structure, densities), fracture, and failure of a study cornice along with meteorological parameters on a ridge near Kootenay Pass, BC during two winter seasons. Monitoring the three-dimensional time-lapse development of the cornice will be achieved using periodic photography and terrestrial photogrammetry methods (Eos Systems Inc., 2004). Deformation and temperature inside the cornice will be measured using glide shoe-type instrument packages (Conway, 1998). These measurements will include linear displacement, tilt, and snow temperature. A nearby weather station will monitor air temperature, relative humidity, wind, snow depth, and radiation. The goal is to develop a numerical model based on these data in order to quantify and predict cornice deformation and failure. REFERENCES Conway, H., 1998: The impact of surface perturbations on snow-slope stability. Ann. Glac., 26, 307-312. Eos Systems, Inc, 2004: PhotoModeler Pro5 User Manual. Eos Systems, Inc., 500 pp. Kobayashi, D., 1988: Formation process and direction distribution of snow cornices. Cold Reg, Sci. and Tech., 15(2), 131. Latham, J. and J. Montagne, 1970: The possible importance of electrical forces in the development of snow cornices. J.Glac., 9(57), 375-384. McCarty, D., R. L. Brown and J. Montagne, 1986: Cornices: Their growth, properties, and control. Proceedings of the International Snow Science Workshop, Lake Tahoe, CA, ISSW Workshop Committee, 41-45. McClung, 1979: In-situ estimates of the tensile strength of snow utilizing large sample sizes. J. Glac, 22(87), 321. McClung D. M. and P. A. Schaerer, 1993: The Avalanche Handbook, The Mountaineers. 272 pp., McClung, D.M., 1996: Effects of temperature on fractures in dry slab avalanche release. J. Geophys. Res. B, 101(B10), 21907-21920. * Corresponding author address: Robert A. Burrows, Avalanche Research Group, Department of Geography, University of British Columbia, 1984 West Mall, Vancouver, BC Canada V6T 1Z2; tel: 604-518-9664; fax: 604822-6150; email: moraineboy@hotmail.com
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,001 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,001 |
| Études des sciences et des technologies | 0,001 | 0,001 |
| Communication savante | 0,000 | 0,001 |
| Science ouverte | 0,001 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».