An Engineering theory of creep of frozen soils

Most of the existing theories of creep have been developed from two different viewpoints: micromechanistic and macroanalytical. The former deal with events occurring at the atomic level and provide knowledge of the processes that control creep. The latter are based on certain macroscopic experimental findings and represent, in fact, an extension of the theory of plasticity to include time and temperature effects. Both the micromechanistic and macroanalytical approaches lead to fruitful results and each can benefit from the other. However, although the former has the advantage of being derived from physical concepts, the use of the latter is often preferred in practice if it provides basic relations that are broad in scope and can lead to improved procedures for designing structures. In this paper, a macroanalytical view of the problem of creep of frozen soils is presented. The proposed theory of creep has been developed mainly with the purpose of being used as a basis for solving a specific soil engineering problem, i.e., the bearing capacity of buried footings and anchors. Since the problem is itself rather complex, it was endeavoured to present the creep information in a relatively simple mathematical form. The theory, while using certain concepts and data from the frozen soils literature, follows more closely, nevertheless, the methods usual in certain engineering theories of creep of metals.La majorit\ue9 des th\ue9ories de fluage existantes ont \ue9t\ue9 d\ue9 velopp\ue9es soit \ue0 partir d'un point de vue micro-m\ue9 canistique, soit \ue0 partir d'un point de vue macroanalytique. Les premi\ue8res traitent des ph\ue9nom\ue8nes se produisant \ue0 l'\ue9chelle atomique et t\ue2chent d'expliquer des processus qui dirigent le fluage. Les derni\ue8res, par contre, sont bas\ue9es sur certaines constatations exp\ue9 rimentales macroscopiques et repr\ue9sentent, en effet, une extension de la th\ue9orie de la plasticit\ue9 dans laquelle on tient compte des effets du temps et de la temp\ue9rature. Les deux types de th\ue9ories de fluage sont utiles en pratique et b\ue9n\ue9ficient l'une de l'autre. Cependant, malgr\ue9 que les premi\ue8res ont l'avantage d'\ueatre d\ue9duites des conceptions physiques, en pratique on pr\ue9f\ue8re souvent utiliser les deuxi\ue8 mes si les relations qu'elles fournissent sont suffisamment g\ue9n\ue9rales et en m\ueame temps assez simples pour permettre une am\ue9lioration des m\ue9thodes de calcul des \ue9l\ue9ments de construction. La pr\ue9sente \ue9tude montre un aspect macroanalytique du probl\ue8me du fluage des sols gel\ue9s. La th\ue9 orie propos\ue9e a \ue9t\ue9 d\ue9velopp\ue9e avec le but principal de servir de base pour la solution d'un probl\ue8me g\ue9otechnique particulier, notamment celui de la capacit\ue9 portante des fondations enterr\ue9es et des acrages. Le probl\ue8me \ue9tant d' une complexit\ue9 consid\ue9rable en soi-m\ueame, on a fait tout effort pour pr\ue9senter l'information de fluage dans une forme math\ue9matique aussi simple que possible. La th\ue9orie utilise certaines conceptions et donn\ue9es tir\ue9es de la litt\ue9rature sur les sols gel\ue9s. N\ue9anmoins, dans sa conception g\ue9n\ue9rale, elle suit de plus pr\ue8s les m\ue9thodes usuelles dans certaines th\ue9ories du fluage des m\ue9taux \ue0 haute temp\ue9rature.Peer reviewed: NoNRC publication: Ye