Construction and Geotechnics

A large number of scientific works by both Russian and foreign authors are devoted to the interaction of a single pile with the surrounding and underlying soils. Based on experimental, numerical and theoretical studies, various methods, approaches and solutions have been obtained in scientific works, which make it possible to most correctly predict the settlement and bearing capacity of a single pile. Research in this area is relevant, since the determination of the settlement of the pile, as well as the study of the mechanism of distribution of the load transmitted to it, play an important role in the design of pile foundations. In this work, the boundary value problem of the interaction of a long and incompressible pile with the surrounding and underlying soils in an elastic-viscous formulation, taking into account soil strengthening, was solved, based on the Maxwell model, as well as on the basis of the rheological model of A.Z. Ter-Martirosyan. This study presents a detailed course of solving the boundary value problem, as well as the basic formulas for calculating the settlement and long-term bearing capacity of a single pile. The change in the curve of dependence σ R ( t ) at different values of soil viscosity is shown when solving the problem in an elastic-viscous formulation. An additional graph of σ R ( t ) dependence is presented showing the difference in the presented soil models. Based on the plotted graphs of the dependence of σ R ( t ) when solving the problem in an elastic-viscous formulation, it can be concluded that the time to reach the maximum value of the load under the foot of the pile is directly proportional to the value of the soil viscosity. When solving the problem on the basis of the rheological model A.Z. Ter-Martirosyan, the maximum value of the load under the foot of the pile is reached earlier than when solving the problem in an elastic-viscous formulation both with and without soil strengthening, which requires additional study.

New technical solutions for the elimination of negative friction forces in the construction of pile foundations on subsidence soils are considered. The friction forces arising between the subsidence soil and the side surface of the pile, according to the Amonton-Coulomb law and the theoretical justifications of B.V. Deryagin, are presented as the sum of a term depending on adhesion and the product of the coefficient of friction by normal pressure. There is some function approximating the total friction force along the side surface of the pile. Differentiating this function, we obtain a formula that determines the change in soil pressure on the side surface of the pile, which varies with the depth of the pile location in the subsidence soil. To sharply reduce the forces of negative friction, the author has developed the design of a pile foundation made of asbestos cement pipes. Studies have shown that in these piles, the forces of negative friction are reduced by 20-30 %, compared with concrete piles manufactured in factory conditions. The author has developed two variants of the method of building a pile foundation on subsident soils, in which the role of antifriction lubricant is performed by a layer of humbrine. Humbrin is a waste of the technology of purification of technical oils. This waste accumulates in large quantities in the landfills of oil refineries. The author has proposed a new design of a pile foundation, in which recycled tires are used as an outer shell to remove the forces of negative friction. Experimental studies have shown that even with vertical deformations of the tire screen of more than 0.04 m, the amount of pile precipitation turned out to be negligible, only 0.02 mm. The author also developed a pile foundation erected on subsident soils. This pile foundation has an external cylindrical shell. In the gap between the cylindrical shell and the side surface of the pile there is a spiral-wound elastic rubber rolling harness. When the surrounding soil subsides, the outer cylindrical shell moves vertically down the rolling spiral bundle, removing negative friction from the side surface of the pile. In addition, the rolling spiral elastic harness also performs the function of a seismic isolator.

The introduction lists the main disadvantages of the traditionally used methods for calculating the stability of slopes and slopes and presents a calculation method in which, for the first time, in our opinion, an attempt was made to construct the most dangerous "slip line" based on the analysis of the stressed state of the soil massif. Further, in the first chapter of the article, three possible approaches to solving the problem of determining the angle of inclination of the most probable shear site at the studied point of the soil massif, based on the analysis of its stress state, are presented and analyzed. The second chapter presents the results of calculating the value of the coefficient of stability of the soil slope by L.G. Fisenko (one of the traditional calculation methods) for two types of sliding line: circular cylindrical (classical case) and constructed by the method of N.S. Nikitin taking into account the operating stresses; and by V.K. Tsvetkov - A.N. Bogomolov. All calculations are performed for one object, the geometric parameters of which and the numerical values of the physico-mechanical properties of the composing soil are given in the article cited below by S.N. Nikitin. As a result, it turned out that the first two coefficients of the margin of stability are respectively equal to K 1 = 1.6 and K 2 = 1.75, and the value of the third coefficient of the margin is equal to K 3 = 2.18. Comparing this value with the values of the coefficients of the margin of stability calculated by the method of S.N. Nikitin and the method of L.G. Fisenko, we see that it is 26 and 20 % higher, respectively, while K 2 > K 1 is 9.4 %. Based on the analysis of the calculation results for the example considered in this paper, it can be stated that methods based on the analysis of the stressed state of the soil mass give higher values of the stability margin coefficients than traditionally used. Thus, the value of the slope stability margin coefficient calculated by the method of V.K. Tsvetkov - A.N. Bogomolov turned out to be equal to K 3 = 2.18. Comparing this value with the values of the stability margin coefficients calculated by the method of S.N. Nikitin and the method of L.G. Fisenko, which are respectively equal to K 1 = 1.75 and K 2 = 1.6, we see that it is 20 and 26 % more than them, respectively. At the same time, K 1 > K 2 by 9.4 % - this indicates that taking into account the stresses during the construction of the sliding line makes its shape different from the circular cylindrical one, which affects the value of the stability margin coefficient.

The objects of research are: ferropyl from self-disintegrating slags of low-carbon ferrochrome, slag from smelting without carbon ferrochrome, ferrite-calcium slag and heat-resistant concrete. Due to the fact that the Russian budget does not provide funding for geological exploration and other survey work to determine the quantity and quality of raw materials for the production of construction products, it is necessary to conduct research on the use of technogenic raw materials as raw materials. The use of technogenic raw materials in the production of construction materials practically reduces many costs not only for geological exploration, but also for the arrangement, including the operation of quarries, to zero. Metallurgical industries (non-ferrous and ferrous) in Russia emit a third of all available emissions from industrial enterprises into the atmosphere, while the volume of metallurgy products (non-ferrous and ferrous) is only 17 % of the total domestic industry. In this work, metallurgical waste was used for the production of heat-resistant concrete: as a calcium-containing component, ferropyl from self-disintegrating slags of low-carbon ferrochrome, as an iron-containing component, ferrite-calcium slag, waste from the processing of copper-zinc concentrates, which is a light yellow material slowly cooled to complete scattering, resembling fine sand, and as an aluminum-containing slag from smelting without carbon ferrochrome. Studies have shown that ferrite-calcium slag contains ferrous iron oxide (fayalite) reacts quickly with Н2РO4 and heats the mixture to the required temperature for the appearance of astringent properties. Studies have shown that thanks to the use of orthophosphoric acid as a binder, it is possible to dispose of up to 85 % of non-ferrous metallurgy waste and at the same time obtain heat-resistant concretes with high physical and mechanical properties.