Browsing by Author "Hembara, Nataliya"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Devising a Procedure for Assessing the Subgrade Compaction Degree Based on the Propagation Rate of Elastic Waves
    (РС Тесhnology Сеntеr, Kharkiv, Ukraine, 2021) Kovalchuk, Vitalii V.; Kravets, Ivan B.; Nabochenko, Olga S.; Onyshchenko, Artur; Fedorenko, Olexander; Pentsak, Andriy; Petrenko, Oleksiy V.; Hembara, Nataliya
    EN: This paper reports the analysis of the methods for estimating the technical condition of the subgrade underneath a constructed railroad track or road during its operation. The study results have proven that the issue related to monitoring and controlling high-quality compac-tion of a heterogeneous subgrade remains relevant and requires the construction of reliable experi-mental methods for assessing the subgrade degree of compaction.A procedure for determining the compaction of subgrade in the laboratory has been devised, based on inertial microcomputer technologies, which makes it pos-sible to assess the degree of com-paction of subgrade soils depend-ing on the propagation rate of an impact's elastic waves.An experimental study has been performed into the propaga-tion rate of elastic waves across a homogeneous subgrade made of coarse-grained sand and a hetero-geneous subgrade made of coarse sand with a layer of clay in the middle of the prism. The study results established that the propa-gation rate of an elastic wave in a heterogeneous subgrade accepts a lower value than the rate of wave propagation in a homogeneous subgrade.Through the dynamic inter-pretation, by using a discriminant statistical analysis, the character-istic features have been defined in the distribution of accelerations in the body of the homogeneous and heterogeneous subgrade, depend-ing on the degree of compaction, which would make it possible to monitor the state of the subgrade during operation. As the degree of the subgrade soil compaction affects the technical condition of roads.
  • Thumbnail Image
    Item
    Microcrack under Internal Pressure at Dislocation Defect
    (Elsevier BV, 2019) Stashchuk, Mykola; Hembara, Nataliya; Kovalchuk, Vitalii V.
    EN: By solving the problem of the theory of elasticity for a boundary dislocation with a cavity on its continuation, a stress-strain state in a solid crystalline body is determined. The correlation for calculating the energy of a body with a dislocation crack under pressure is obtained. The geometric parameters of a crack-like dislocation cavity are calculated. The values of equilibrium and non-equilibrium crack lengths are established on this basis. Also the value of the critical pressure at which the dislocation crack start begins is received. Stress intensity factors for the dislocation crack are obtained and calculated. Physical essence of fracture toughness is established using stress intensity factors.