METHODS OF DETERMINING THE COEFFICIENT OF MOISTURE CONDUCTIVITY OF SOILS SUBGRADE
Authors:   National Transport University (NTU), Kyiv, Ukraine, Bondarenko Lyudmila , Kvatadze Yevheniia ,   National Transport University, Kyiv, Ukrainе
Published: October 2022

Introduction. All periods of moistening of the road structure constitute a single regular cycle of moisture movement in it due to the influence of natural factors. For the final selection of the construction of the subgrade and road pavement, the values of density, humidity and frost heaving of the soil in the annual cycle should be established. To forecast these values, it is necessary to determine the amount of moisture entering the soil from precipitation falling on the surface of the roadway and roadsides during periods of seasonal moisture accumulation. This makes it possible to develop high-quality measures that improve the water-thermal regime of the soils of the subgrade, to model its construction taking into account the properties of the soil, to increase durability by increasing the degree of soil density and reducing the harmful effects of moisture infiltration. Problem Statement. Coefficient of soil moisture conductivity of soil is obtained by the existing method I.A. Zolotar. According to the international standard ISO 17892-11:2019 (E), there are different values as well as different units of measurement, which creates significant problems for their further practical use. Therefore, there are a number of urgent problems regarding the adaptation of existing methods for determining moisture accumulation during the annual cycle to European standards for measuring the coefficient of moisture conductivity of soils of the subgrade. Purpose. The purpose of this work is to carry out analysis of the existing methods of determination of soil moisture conductivity coefficient for calculation of seasonal moisture accumulation in the subgrade. Materials and methods. Methods of determination of the coefficient of moisture conductivity, in particular The Method I.A. Zolotar, are used mainly in the countries of the post-Soviet space. At the same time, in the European Union countries, the determination of the coefficient of moisture is regulated by the international standard ISO 17892-11:2019 (E), according to which the coefficient of moisture is determined depending on the conditions of carrying of the experiment. In the educational and scientific laboratory of the department of transport construction and property management of the National Transport University, a series of studies was conducted using equipment for testing moisture conductivity under conditions of constant pressure. Results. Based on the obtained results of experimental studies carried out in the research laboratory of the National Transport University, the coefficient of moisture conductivity of sandy soil was determined according to the international standard ISO 17892-11:2019 (E) and a comparison was made with the coefficient of moisture conductivity calculated according to the method of I.A. Zolotar. Conclusions. On the basis of the obtained results of experimental studies according to the European approach to determining the coefficient of electrical conductivity of soils of the subgrade, the method of calculating seasonal moisture accumulation will be improved. This will make it possible to move away from outdated Soviet methods, to solve a number of issues important for the practice of design, construction, restoration, reconstruction and operation of roads: to assess the suitability of local soils for the arrangement of the subgrade; determine its structural parameters; to establish calculated values of strength and deformation characteristics of the soil.