ANALYSIS AND PROGNOSIS BY THE METHOD OF BOUNDARY ELEMENTS OF THE INTERACTION OF THE SOIL BASIS WITH THE CHIMNEY

Abstract

Problems of estimating the load bearing capacity of the foundations of the underlying loads are crucial in practical design, since the index of operational suitability of the objects is the actual carrying capacity of the underground part of the building, the installation of which requires taking into account all the properties of the soil of the construction site, since the foundation should be the most rational, and its subsidence should not exceed the maximum allowable values.

The process of exploitation of buildings, namely the calculation of their stability, strength, deformability, the choice of optimal constructive solution, is impossible without the transition to a mathematical description. It contributes to this numerical experiment, the appearance of which substantially brought fundamental mathematical problems to the applied, connected the physical content of the problem, mathematical formulation and numerical method of solution.

For the purpose of more objective and fuller analysis of soil bearing capacity and prediction of potential deformations, calculations of the stress-strain state (SSS) of soils with the use of regularities of non-linear soil mechanics are required.

To this day, the question is to create a settlement soil model that would provide the possibility of compactness, clarity of the research process, the possibility of numerical analysis and embraced the whole set of its natural properties, the main of which is the discreteness (or granular structure of soils), which differentiates it from solids. Its consideration offers more opportunities for the theory and experiment to fit.

The dispersed medium of the soil basis has its own peculiarities of deformation. At the current level of soil mechanics development, models are aimed at revealing the processes of deformation of a continuous medium to determine the SSS on a soil basis. It is known that most of the physical phenomena in mechanics can be described using differential equations in partial derivatives, for solution of which it is necessary to involve modern numerical methods: the finite element method (FEM), the method of boundary elements (BEM).

The lack of guidance in existing state building codes on how to calculate deformations of bases under ring foundations prevents their widespread adoption, although for a number of structures (smoke pipes, cooling towers, TV towers) the use of these foundations is most expedient.

In the article the possibility of reliable prediction of the behavior of the ring foundation (which is performed by sampling the boundary surface of the foundation and the active soil zone for the BEM) and deformation of the soil in a wide range of loads is provided by the elaborate mathematical model. In the article, the robust mathematical model provides the possibility of reliable prediction of the behavior of the ring foundation (which is performed by sampling the boundary surface of the foundation and the soil active zone for the MGE) and deforming the soil in a wide range of loads. In what as the fundamental solutions, expressions for displacements and stresses obtained by R. Mindlin from the action of the unit concentrated force applied in the middle of an elastic half-space were used. On the basis of these expressions, a calculated matrix of influence of the BEM was constructed.

The results of the forecasting by the BEM are presented in the loading-settling diagrams of the ring foundation. The fidelity of the choice of the settlement dilatation model is confirmed by the correspondence of numerical studies using the FEM.