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Simulated Glacier Sliding over an Obstacle

  • R. Brepson (a1)

Abstract

The sliding of temperate ice over two obstacles with sine-wave profiles (wavelength, 0.53 m; maximum slope, 0.22) and low thermal conductivity has been reproduced at full scale within a steel chamber. As expected, large cavities form between the ice and the obstacles so that the drag is limited. However, the delayed elasticity of bubbly ice modifies the expected behaviour. At the base of the ice a fine-grained, bubble-free blue ice layer develops. The shear strain concentrates on the up-stream side of bumps and in the blue ice layer. Tap-water ions enhance tertiary creep-rates.

Résumé

On a reproduit le glissement d’un glacier tempéré sur deux bosses (longueur d’onde, 0,53 m; pente maximale, 0,22) en vraie grandeur dans unc chambre d’acier. Il se forme vraiment de grandes cavités, qui empêchent le frottement de s’élever, mais l’élasticité différée de la glace bulbeuse modifie le comportement auquel on s’attendait. A la base se développe une couche de glace bleue, sans bulles et à grains fins. Le cisaillement se concentre sur la face amont des bosses et dans la couche de glace bleue. Les ions de l’eau de ville favorisent le fluage tertiaire.

Zusammenfassung

Das Gleiten eines temperierten Gletschers über zwei Buckel (Wellenlänge, 0,53 m; maximales Gefälle, 0,22) wurde im Originalmassstab innerhalb einer Stahlkammer nachgebildet. Es bilden sich tatsächlich grosse Hohlräume, die ein Anwachsen des Zugwiderstandes verhindern, doch verändert die verzögerte Elastizität blasenreichen Eises das erwartete Verhalten. An der Unterseite entwickelt sich eine Schicht feinkörnigen, blasenfreien Blaueises. Die Scher-spannung konzentriert sich auf die stromaufwärts gelegene Seite der Buckel in der Blaueisschicht. Die Ionen des Leitungswasser begünstigen tertiäres Kriechen.

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Copyright

References

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Simulated Glacier Sliding over an Obstacle

  • R. Brepson (a1)

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