THERMAL AND HUMIDITY CONDITIONS OF WALL STRUCTURES BORDERING THE GROUND

Abstract

According to the current requirements for the development of civil protection engineering and technical measures during the reconstruction of buildings, it is necessary to convert basements into dual-purpose rooms. A technical inspection of the basement structures revealed that the vast majority of them were in an unsuitable condition for normal operation. One of the objects of the inspection was a dual-purpose room - the basement of a university building in Poltava. The inspection revealed soaking of the walls bordering the ground, leaching of mortar between bricks and foundation blocks, and flooding of the basement.  In order to determine the thermal and moisture characteristics of the soil around the foundation zone of a public building with an exploited basement, the coefficient of thermal conductivity of the soil was studied, and its moisture content was determined under operating conditions. The research was carried out in the laboratory at the Structural Physics Laboratory of the National University ‘Yuri Kondratyuk Poltava Polytechnic’ on the test samples taken during the excavation of the soil around the university's academic building in Poltava. The thermal conductivity coefficient was measured with the thermal conductivity meter ITS-1. To determine the thermal conductivity of the soil. Five samples were selected. Each sample measured 150×150 mm and was 20-30 mm thick. The value of the thermal conductivity coefficient averaged 1.718 W/m∙K. To study the influence of the characteristics of the soils in the near-foundation zone on the thermal and humidity states of structures bordering the soil, the corresponding unit was modeled using the finite element method. To determine the effect of the thermal conductivity coefficients of the soils in the near-foundation zone on the temperature of the inner surface of the basement wall, a model of a fragment of the corresponding enclosing structure was developed. During the experiment, the thermal conductivity coefficients for soils of different densities (sand, sandy loam, loam, and clay) were analyzed. The maximum and minimum values of the thermal conductivity coefficients for these soils were selected. Comparative diagrams were drawn to better understand the temperature and heat flows in the basement wall structure. Based on the results of the study of the building envelope bordering the ground and the operated premises, it was determined that at all reconstruction sites, it is necessary to restore the external vertical waterproofing layer and perform insulation. Conclusions: When calculating the thickness of insulation of wall structures bordering the ground, it is necessary to take into account the thermal insulation characteristics of the soil around the foundation zone; the thermal insulation properties of the soil (soil thermal conductivity coefficient of 1.5-2 W/m∙K) are insufficient for basement insulation; the type of soil around the foundation zone is non-insulated.