SOME FEATURES OF ASSESSING THE STABILITY OF HYDROTECHNICAL STRUCTURES GIVEN THE ANISOTROPY OF THE STRESS-DEFORMED STATE OF THEIR SOIL BASES

The processes that cause degradation of soil properties, decrease in their strength and increase in deformability was analized. Solving the problem of determining phase velocities and vectors of elastic displacements made it possible to establish the differential coefficient of elastic anisotropy of soils that form the basis of hydraulic structures. Experimental studies of soils, which are the basis of hydraulic structures, when using ultrasonic methods made it possible to determine the factors that cause the anisotropy of elastic waves. The most informative parameter of the anisotropy of soils, which are the basis of hydraulic structures,was established. The main indicators of the manifestation of azimuthal anisotropy of bulk elastic waves were determined. The study of samples of soil bases of hydraulic structures when using the invariant-polarization method made it possible to experimentally establish the type of anisotropy and determine the value of the coefficient of elastic anisotropy of the studied samples. The angle of deviation of the elastic displacement vector from the direction of the wave normal, exceeding 90°, is a sign of possible destruction of the soil base of a hydraulic structure and enables us to localize zones of limit equilibrium. A study of sandstone samples was carried out when using atomic force microscopy to investigate the degree of change in the microstructure of the soil bases of hydraulic structures. The use of the acoustic emission method allowed us to obtain an image of the acoustic response during laser irradiation, which made it possible to evaluate the diffraction pattern of the studied sandstone samples. It was established that a characteristic feature of the acoustic emission spectrum of the studied samples of soil bases of hydraulic structures is the presence of numerous secondary maxima. Their occurrence indicates the complexity of the material composition and structure of soil bases, in particular, a specific combination of allotigenic and authigenic minerals, cementing substances and textural features. In the case of irreversible deformations, the influence of fluid saturation manifests itself through differential-elastic effects, caused by both the crystal structure and the nature of interphase bonds, as well as the temperature, pressure and other parameters of the soil base environment of hydraulic structures.