ABSTRACT
Mechanical processes in soils are the processes generated by internal stresses of various kinds resulting in elastic, viscous, or plastic strains occurring with or without breakage of the continuity of their material (Goldshtein, 1952; Vyalov, 1978). Internal stresses in frozen soils are due to a change in the main thermodynamic parameters. These are the external pressure (P), temperature (t), and volume (V). In this connection the stresses may be divided into two groups. The first group of stresses is associated with an application of an external pressure. The mechanical processes (compressive, tensile, shear strains) developing in this case may be considered baromechanical processes . The second group of stresses is generated inside a soil body as a result of nonuniform changes in the elements of its volume due to physical and chemical processes, such as desiccation, moistening, heating, cooling, moisture phase transitions, and migration with changes in volume (Taber, 1930; Fedosov, 1935; Edlefsen and Anderson, 1943; Yershov, 1986; Henry, 2000), etc. Non-uniform changes in the volume elements (V) related to each other occur due to dissimilar changes in the parameters of the soil body, such as temperature , liquid moisture content (W), ice content (Wi), etc., resulting in temperature strains, swelling strains, heaving-out and some other processes. One can recognize two types of physico-mechanical processes in this group of strains and stresses. These are the volume-gradient stresses and strains in frozen soils induced by a change in their negative temperature ( thermo-mechanical processes ), and the volume gradient strains and stresses in freezing-thawing soils induced by moisture phase transitions, migration, and processes of texture formation ( aggregation, dispersion, coagulation ) of soil particles.
