Basis of method for predicting thermal stresses and deformations in frozen soils
The mechanical properties of frozen soils are described in terms of creep, relaxation and strength. Equations are presented which describe the behaviour of each property authenticated by laboratory and field work. The main part of the work is on the thermal deformation of laboratory prepared frozen...
| Main Authors: | , |
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| Format: | Report |
| Language: | English |
| Published: |
National Research Council of Canada
1976
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| Subjects: | |
| Online Access: | https://doi.org/10.4224/20359113 https://nrc-publications.canada.ca/eng/view/ft/?id=a261d401-48ba-43a3-9906-aa59715c06ea https://nrc-publications.canada.ca/eng/view/object/?id=a261d401-48ba-43a3-9906-aa59715c06ea https://nrc-publications.canada.ca/fra/voir/objet/?id=a261d401-48ba-43a3-9906-aa59715c06ea |
| Summary: | The mechanical properties of frozen soils are described in terms of creep, relaxation and strength. Equations are presented which describe the behaviour of each property authenticated by laboratory and field work. The main part of the work is on the thermal deformation of laboratory prepared frozen soils, followed by treatment of the thermal stresses in undisturbed frozen soil. Patterns of thermal deformation were determined experimentally. The shape of the curves indicates that stabilization of thermal deformations occur slowly even after the temperature of the specimen becomes constant. The thermo-rheological processes in frozen soils are best described if the soil is regarded as a visco-elastic model of the Bingham-Shvedov type. Deformation consists of two parts, elastic and visco- plastic. The peculiar mechanism of thermal deformations and stresses during freezing of the active layer can be compared to shrinkage during hardening of metal alloys. The difficulty in establishing relationships is that the dynamics of the temperature field in a freezing layer is so extremely complex. The moisture content of the active layer after freezing is at a maximum at the surface and decreases until it is at a minimum at the bottom of the active layer. Because of this variation the dynamics of thermal stresses also change with depth. In most cases the stresses at depths about 2/3 down the active layer in the first half of the cold period must be tensile stresses. At the same time compression stresses may occur in the upper layers. Fissures may develop at depth without showing at the surface. Les propriétés mécaniques des sols gelés sont décrites en fonction de leur fluage, de leur relaxation et de leur ré sistance. Des équations sont présentées pour décrire le comportement de chacune de ces propriétés telles qu'observé es en laboratoire et sur le terrain. Peer reviewed: No NRC publication: Yes |
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