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Stress relaxation characteristics of warm frozen clay under triaxial conditions
Abstract Stress relaxation is one of the main concerns in geotechnical engineering, especially in permafrost regions with warm frozen soil. This paper investigated the mechanical behaviors of a warm frozen soil during relaxation process. A series of triaxial relaxation tests were carried out on the warm frozen soil samples under the temperature from −1.0°C to −0.2°C and confining pressure of 0.5MPa to 3.0MPa. Three stages were observed during the whole stress relaxation process, i.e. instantaneous relaxation, intense relaxation and slow relaxation. Relationship between deviatoric stress and time was described by a hyperbolic relationship. With relatively small pre-strain (3% and 4%), volumetric changes during stress relaxation contracted initially followed by expansion, but contraction dominates the relaxation process with the magnitude of pre-strain over 6%. Characteristic parameters such as the instantaneous stress relaxation, the critical relaxation duration and relaxation rate are defined and analyzed. It is found that the parameters are all dependent on soil temperature, confining pressure and magnitude of pre-strain.
Highlights ► The relaxation process of warm frozen clay consists of three typical stages. ► The magnitude of pre-strain influences the volumetric changes during relaxation. ► Deviatoric stress–time relationship can be well described by a hyperbolic relation. ► Characteristic parameters during relaxation depend on the initial test condition.
Stress relaxation characteristics of warm frozen clay under triaxial conditions
Abstract Stress relaxation is one of the main concerns in geotechnical engineering, especially in permafrost regions with warm frozen soil. This paper investigated the mechanical behaviors of a warm frozen soil during relaxation process. A series of triaxial relaxation tests were carried out on the warm frozen soil samples under the temperature from −1.0°C to −0.2°C and confining pressure of 0.5MPa to 3.0MPa. Three stages were observed during the whole stress relaxation process, i.e. instantaneous relaxation, intense relaxation and slow relaxation. Relationship between deviatoric stress and time was described by a hyperbolic relationship. With relatively small pre-strain (3% and 4%), volumetric changes during stress relaxation contracted initially followed by expansion, but contraction dominates the relaxation process with the magnitude of pre-strain over 6%. Characteristic parameters such as the instantaneous stress relaxation, the critical relaxation duration and relaxation rate are defined and analyzed. It is found that the parameters are all dependent on soil temperature, confining pressure and magnitude of pre-strain.
Highlights ► The relaxation process of warm frozen clay consists of three typical stages. ► The magnitude of pre-strain influences the volumetric changes during relaxation. ► Deviatoric stress–time relationship can be well described by a hyperbolic relation. ► Characteristic parameters during relaxation depend on the initial test condition.
Stress relaxation characteristics of warm frozen clay under triaxial conditions
Wang, Songhe (author) / Qi, Jilin (author) / Yao, Xiaoliang (author)
Cold Regions, Science and Technology ; 69 ; 112-117
2011-06-30
6 pages
Article (Journal)
Electronic Resource
English
Stress relaxation characteristics of warm frozen clay under triaxial conditions
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