ABSTRACT
The phenomenological models of soil behaviour in the process of shear and internal bulge set forth underneath have been put into the foundation of special instruments, test methods and calculation schemes. Each of these models is a combination of a sliding model and an elastic model. Two propositions are included in the basis of shear models: soil failure in the process of shear is localized in the layer (band) along the contact surface; and dilatancy of the shear layer causes elastic resistance of the soil massif. This presupposes that purely plastic (deviatory) deformation takes place in the shear layer, whereas elastic (tensor) deformation occurs in the massif. The state when an infinitely small increment of the shearing load causes rolling of contact layer grains, corresponds to limiting equilibrium. It is the case of the so-called kinematic equilibrium, which is characterized by constant sliding speed and constant value of shearing stress.
