"Вестник МГСУ"

Subject: one of the promising trends in the development of structural mechanics is the development of methods for solving problems in the theory of elasticity for bodies with continuous inhomogeneity of any deformation characteristics: these methods make it possible to use the strength of the material most fully. In this paper, we consider the two-dimensional problem for the case when a vertical, locally distributed load acts on the hemisphere and the inhomogeneity is caused by the influence of the temperature field. Research objectives: derive governing system of equations in spherical coordinates for determination of the stress state of the radially inhomogeneous hemispherical shell under locally distributed vertical load. Materials and methods: as a mechanical model, we chose a thick-walled reinforced concrete shell (hemisphere) with inner and outer radii a and b, respectively, b > a. The shell’s parameters are a = 3.3 m, b = 4.5 m, Poisson’s ratio ν = 0.16; the load parameters are f = 10MPa - vertical localized load distributed over the outer face, θ0 = 30°, temperature on the internal surface of the shell Ta = 500 °C, temperature on the external surface of the shell Tb = 0 °C. The resulting boundary-value problem (a system of differential equations with variable coefficients) is solved using the Maple software package. Results: maximal compressive stresses σr with allowance for material inhomogeneity are reduced by 10 % compared with the case when the inhomogeneity is ignored. But it is not so important compared with a 3-fold decrease in the tensile stress σθ on the inner surface and a 2-fold reduction in the tensile stress σθ on the outer surface of the hemisphere as concretes generally have a tensile strength substantially smaller than the compressive strength. Conclusions: the method presented in this article makes it possible to reduce the deformation characteristics of the material, i.e. it leads to a reduction in stresses, which allows us to reduce the thickness of the reinforced concrete shell, and also more rationally distribute the reinforcement across the cross-section, increase the maximum values of the mechanical loads.

Urban conditions are characterized by geographical and climatic features, geotechnical and hydrogeological conditions. But the main features are architecture, urban planning and engineering infrastructure solutions. This includes roads, water mains, electrical networks, sewage, heating system. Saturation of urban areas by engineering services depends on the size of the city, its population and climatic conditions. Metropoles and cities with long heating season are of particular importance in terms of this issue.The article discusses the need for full-scale investigation of the distribution of temperature field in the soil and underlying sediments during the engineering and environmental surveys in urban environment. In order to study the transfer of heat and moisture in clay soils and to assess its influence on their physical and mechanical properties the authors propose the principles of interaction simulation of the soil and the thermal field. We propose a preliminary methodology for monitoring the temperature and humidity of the soil mass under the influence of heat-conveying communications. Among these communications there are heating, water mains, hot water supply and sewerage.The location of the communications in the near-surface soil mass and the presence of sufficiently high temperature loads from mains are taken into account. To date there is no information on the monitoring of the nature of the distribution of the soils temperature field in urban areas and, accordingly, the spatial variability of the physical and mechanical properties of soils under natural conditions.The reason for it is in short term of geotechnical investigations for specified objects on the stage of project documentation development. Also in the conditions of a city it's almost impossible to place an experimental site with expensive facilities — wells and equipment and provide its safety for a long time (at last 1 year or more).The paper describes the laboratory setup and principles of equipment monitoring systems in field conditions, the basic principles of the experimental work techniques. The theoretical generalization of the results of methodological experiments and conduct large-scale field experiments is a challenge for further research.