Downdrag loads developed by a floating ice cover: field experiments

• Main Author: Frederking, R. M. W.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 1974
• Subjects: permafrost; pergélisol; soils; sol (terre); ice loads; charge de glace; vertical loads; charge verticale; shear stresses; contrainte de cisaillement; creep; fluage; Ice
• Online Access: https://nrc-publications.canada.ca/eng/view/ft/?id=e369b6d8-d63c-4e9e-ba79-7824c58195b2; https://nrc-publications.canada.ca/eng/view/object/?id=e369b6d8-d63c-4e9e-ba79-7824c58195b2; https://nrc-publications.canada.ca/fra/voir/objet/?id=e369b6d8-d63c-4e9e-ba79-7824c58195b2

The first phase of an investigation of the vertical forces developed on a structure by a floating ice cover frozen to it is described. It is the objective of this work to develop the theoretical, experimental, and field aspects of vertically acting loads required for the more efficient design of structures subject to such loads. A load frame was constructed that would apply constant upward acting loads to wooden piles frozen into an ice cover composed mainly of snow ice. Load, ice temperatures, and movement of the pile in relation to the ice were measured. The time- dependent movement of the pile in relation to the ice exhibited creep characteristics, and these results were related to shear creep for grouted rod anchors in permafrost. Results of a previous study for WF steel H- beams in ice were also considered. The steady-state creep displacement rate for wooden piles in ice, rod anchors in permafrost, and WF steel H-beams in ice exhibited a comparable dependence on the constant applied shear stress. The steady-state creep displacement rate of a 100-mm wooden pile in snow ice at -3 degrees C and under a constant applied shear stress of 180 kN/m[2] was about 1mm/day. L'article décrit la première phase d'une étude des forces verticales développées sur une structure par un couvert de glace flottant gelé sur cette structure. L'objectif de ce travail est de développer les aspects théorique, expérimental et pratique de l'action des forces verticales dans le but d'arriver à un dimensionnement plus efficace des structures soumises à de telles forces. On a construit un bati de chargement pour appliquer des forces d'arrachement constantes à des pieux de bois gelés dans un couvert de glace composé essentiellement de glace de neige. La force, les températures de la glace et les mouvements du pieu par rapport à la glace ont été mesurés. Les mouvements en fonction du temps du pieu par rapport à la glace ont pré senté des caractéristiques de fluage, et les résultats ont été reliés au fluage en cisaillement pour des ancrages ...