Behavior of circular footings and plate anchors in permafrost

• Main Authors: Ladanyi, B., Johnston, G. H.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 1974
• Subjects: permafrost; pergélisol; soils; sol (terre); creep rate; taux de fluage; bearing capacity; portance du sol; failure loads; charge de rupture; foundation components; semelle de fondation
• Online Access: https://nrc-publications.canada.ca/eng/view/ft/?id=69e08abc-7994-4188-b8e4-39ca4634e67b; https://nrc-publications.canada.ca/eng/view/object/?id=69e08abc-7994-4188-b8e4-39ca4634e67b; https://nrc-publications.canada.ca/fra/voir/objet/?id=69e08abc-7994-4188-b8e4-39ca4634e67b

The purpose of this paper is to develop a method for predicting the creep settlement and the bearing capacity of frozen soils under deep circular loads. The theory uses experimentally determined creep parameters of frozen soil and is intended to be applicable to the design of deep circular footings and screw anchors embedded in permafrost soils. On the basis of available experimental evidence, it was concluded that a mathematical model different from that usual in soil mechanics should be used in solving the time- dependent bearing capacity problem of such footings. The solution proposed in the paper was obtained by using the mathematical model of an expanding spherical cavity in a nonlinear viscoelastic-plastic medium with time, temperature, and normal pressure dependent strength properties. For a given footing or anchor, the theory furnishes either isochronous load-displacement curves, or load-creep rate curves, or a time-dependent bearing capacity for which formulas and graphs of nonlinear elastic-plastic bearing capacity factors are supplied. The theoretical predictability of creep rates and ultimate failure loads was checked against the results of screw anchor tests carried out by the Division of Building Research, N.R.C.C., at a permafrost site in Thompson, Manitoba. It was found that the use in the theory of the creep parameters determined by creep-pressuremeter tests performed at the site, resulted in a satisfactory agreement between the predicted and the observed behavior. Le but principal de cette communication est de présenter une méthode par laquelle il serait possible de prévoir le tassement dû au fluage des sols gelés et leur capacité portante lorsque sollicités par des charges circulaires profondes. Son domaine d'application est le calcul des fondations circulaires et des ancrages établis profondement dans le pergélisol. A partir des résultats expérimentaux disponibles, on est arrivé à la conclusion que, dans la solution du problème de la capacité portante à long terme de telles fondations, il ...