Scientific Journal of KubSAU

Hardening of clay soil manifests in the form of increase of the resistance of sample to shear deformation. The shear tests of normally compacted and overcompacted soils give values of peak strength at small strains and long-term strength at high. A shear test with constant strain rate of deformation (CRD) with continuous recording of resistance encounters uneven resistance change and the cyclical rate of change of resistance (RCR). The identification of cycles of the SIS allowed us to divide the deformation in each cycle for elastic and inelastic, corresponding to the ascending and descending branches of cycle. On an interval of the total resistance, the increases of the increment of inelastic strain are positive up to some critical value of the total deformation of the sample at which their sum reaches a maximum. This maximum is adopted as a measure of hardening. With further shearing of the sample, inelastic increments are negative, and their sum is monotonously decreases and reaches negative values for the total destruction of the sample. This value is taken as the softening. A symptom of total failure of the sample is the decline of absolute values of inelastic increments of resistance to zero. In general, the trend of the increments of inelastic and elastic increments of the resistance of the sample indicates the development of the destruction of the soil sample on the sliding surfaces and, in particular, yielding of the total surface. The sum of elastic increments of the resistance monotonically increases throughout the shear

The object of the study is bored piles and their joint work with clay soils. The analysis of the field of static tests of bored piles, arranged by continuous flight auger technology (CFA), was carried out by repeated loading. Curve of settlement and the rate of its development from the applied force was obtained. Linear relationship reducing the amount of settlement in the second cycle from residual displacements after unloading pile on the first cycle was found. There was a relationship increment of settlements in the second cycle from the involvement of the bottom end in the work

The filling piles and their joint work with soil are the objects of research. The joint working of filling piles and soil has been researched with the constant rate of loading (CRL) and the continuous measuring of deformations of physical model. The experiment was realized at the physical model of filling pile in soil with the apparatus AKP-6NM. The hypothesis of mechanical working of near-pile soil was proposed as the result of the experiment