Subject: an analytical solution to the problem of interaction of the pile and the raft plate with the surrounding soil taking into account the possibility of expansion of the pile’s shaft is given. Closed solutions are obtained for determination of stresses in the pile’s shaft and in the soil under the raft plate. We take into account the effect of prestress of the base after compaction on formation of stress-strain state during construction and operation of structures. These solutions are relevant for compaction piles made of crushed stone or soil-cement piles whose stiffness is comparable with the stiffness of the surrounding soil. Research objectives: determination of the average strength and deformation parameters of weak soils subjected to transformation using the piles of finite stiffness made of loose gravel material and soil-cement material; comparative analysis of the obtained results with the data of in situ tests on a construction site. Materials and methods: when solving the problem of interaction between the pile and the surrounding soil with the expansion of pile’s shaft, analytical solutions based on well-known expressions of classical soil mechanics and solid mechanics are used. Experimental studies were carried out on a certified laboratory equipment and with the help of field methods regulated by the existing design codes. Results: the presented technique of improving mechanical parameters of soils and the method of their calculation in the transformed foundation allow us to determine the average characteristics of strength and deformability of the entire foundation. These techniques are necessary for analysis of the transformed foundation by two types of limit states in the process of designing the structure by analytical and numerical methods. Conclusions: the resulting dependencies and the proposed techniques for designing reinforcement of the base with the help of pile-drains are used on real construction sites. We present the results of large-scale tests at the experimental site for construction of a large energy facility in Russia as well as at the housing construction site in the Central region of the Russian Federation.

Subject: foundatons of high-rise buildings in Tyumen which possess the properties of active regulation of their interaction with the soil bed. Research objectives: assessment of the experience of using soil bed pressing for combined footings, and application of strip-shell footings for construction of high-rise buildings (up to 25 floors or 75 m high) in the presence of highly compressible soil. Materials and methods: geotechnical monitoring data of the technical condition of residential high-rise buildings during the construction process and in operation. Results: the results of monitoring 17-storey residential building and three 22-storey residential buildings prove that the strip-shell foundation is highly efficient. Its efficiency consists in decrease of settlements as compared to slab foundations, and also reduction of cost and construction duration. Practical applications of combined strip-pile foundations with the possibility of regulation of stress-strain behavior of soil bed by its pressing confirmed the efficiency of the developed design solutions. This efficiency consists in assurance of operational reliability of objects of construction, and also decrease of material consumption and the cost as compared to traditional pile-slab foundations. Conclusions: taking into account the obtained results and a general progress in geotechnical science and technologies, practical application of foundations which possess the properties of active regulation of their interaction with the soil bed allows us to decrease the cost associated with their construction for high-rise buildings, especially in the presence of highly compressible soil beds.

Subject: a computational scheme of the bottom of deep foundation for analyzing vibrations of the “pile-heavy foundation” system is proposed. It is shown that, in this case, accounting for inertial forces of the pile and friction along the lateral surface of the pile leads to a non-periodic (non-harmonic) damped oscillation of the deep foundation. Research objectives: assessment of displacement and resistance along the lateral surface of a pre-fabricated reinforced concrete pile under vibratory immersion; estimation of key factors affecting resistance of the pile in vibratory immersion. Materials and methods: when solving the problem of interaction between the pile and the surrounding soil during vibratory immersion, analytical solutions of the static and dynamic problems using modified rheological models of soils were used. Analytical solutions are obtained using the software package MathCAD. Comparison of the results of analytical calculations with numerical solutions is performed in the PLAXIS 2D geotechnical software package that implements the finite element method. In the numerical solution of the problem of interaction between the pile and the surrounding soil, an elastoplastic model with Mohr-Coulomb hardening was used. Results: when solving the problem of oscillation of the “system”, various contact models are considered for calculations, including elastic, nonlinear and rheological, taking into account time-dependent hardening. Rheological parameters of soils are used, which can be determined on the basis of special laboratory studies. Conclusions: the proposed scheme for interaction between the pile and the surrounding soil during vibratory immersion describes, with sufficient accuracy, the oscillations of a weighty pile on a viscoelastic soil base, taking into account the resistance along the lateral surface and the frictional forces at the pile-soil contact. The performed analytical and numerical analysis of the proposed model showed qualitative agreement. Allowance for friction along the lateral surface of a weighty pile significantly influences the vibration characteristics of a deep foundation.

Subject: for many centuries the yard was the social centre of residential development. However, the problems of its spatial organization often do not receive appropriate attention in modern cities. The city of Yerevan, in this sense, is also not an exception, where the new socio-economic conditions that emerged in the early 1990s led to radical changes in the residential development organization. Under this impact, a serious transformation has also been made to the yard space, which is the subject of this study. Research objectives: identification of the main stages of the yard space evolution in the residential building development of Yerevan in the 20th century and the revelation of its characteristic features. Materials and methods: the work is carried out on the basis of observations and published sources by the method of theoretical research, analysis and generalization of the material. Results: the work is composed of the following thematic subdivisions: the yard in the structure of traditional housing (in residential buildings of the 19th and early 20th centuries); development of the yard space in the new format of perimeter-quarter development (in the system of perimeter development of streets in the 1920-1950s); problems of yard organization in open compositions of building development (in the new forms of free building development by standardized elements in 1960s); attempts of yard restoration in the systematized compositions of building development (in the process of formation of large complexes of building development in 1970-1980s); loss of the yard space in contemporary conditions (in the residential building development formed since 1990s in the new socio-economic conditions). Conclusions: based on the results of the analysis, classification of the main stages of the yard space organization evolution during the last century is presented. This classification must be included in the process of the general study of development of residential architecture of Yerevan in the 20th century.

Recently, civil buildings are increasingly using composite reinforced concrete and steel (RCS) structures (beams, slabs, columns). Prestress in RCS structures has not yet found such a spread as, for example, in reinforced concrete and metal structures, although its use is known from technical sources. The present article is devoted to the evaluation of the stress-strain state of prestressed RCS beams. The procedure and results of computer modeling of the response of composite RCS beams consisting of steel I-beam, anchors, prestressed reinforcement and concrete are given. Two variants of arrangement of prestressed reinforcement are considered. According to the data of numerical studies, full-scale samples of beam models were made and their tests were carried out. The article presents the test procedure, the results of experimental studies in the form of graphs, diagrams. At the end of the article, analytical expressions are given for analysis of composite RCS beams of the described cross-section. Results of calculations, comparison of the results of numerical and full-scale experiments are presented. Subject: based on computer simulation and full-scale experiments, the stress-strain state of prestressed composite beams was investigated. Beams were studied with the arrangement of prestressed reinforcement along the I-beam flanges and along the envelope of the bending moment diagram. Research objectives: analyze the stress-strain state of beams, identify effectiveness of the arrangement of prestressed reinforcement. Materials and methods: for full-scale experiments, steel I-beams with lateral cavities filled with concrete were adopted, rod reinforcement was used as a prestressed reinforcement, and a dynamometric key was used for prestress (preload). ANSYS software package was used for computer modeling. Results: the computer simulation data of the stress-strain state of beams is obtained. The results are used for making full-scale samples. The obtained results of computer simulation are compared with the data of full-scale experiments. Conclusions: essential features of the response of prestressed composite beams are studied from numerical modeling, in-situ experiments and analytical calculations. The proposed calculation method gives a good match with the experimental data.

The article contains a description of the methodology and the results of field experiments on self-healing in the impervious element of bored piles filled with clay-cement concrete at the site of temporary shoring of excavation pit of the main structures of Nizhne-Bureyskaya HPP. The results of the experiments allowed us to determine the suitability of local sand from the quarry №5 for self-healing of cracks. Recommendations for quality control of the sandy soil, placed into the transition zones of the dam, were developed. Subject: field studies of colmatization of through cracks in clay-cement concrete diaphragm of earth dams at the site of temporary shoring of excavation pit of the main structures of Nizhne-Bureyskaya HPP. Research objectives: determine possibility of application of the sand material, existing in local quarries, as a contact layer that provides self-healing of cracks in case of their creation in the body of the clay-cement concrete diaphragm of the earth dam of Nizhne-Bureyskaya HPP in the process of its operation. Materials and methods: field experiments were conducted on a transverse shoring of the excavation pit of the main structures of Nizhne-Bureyskaya HPP. Conducted experiments consisted in self-healing of artificial cracks by sandy material arranged in clay-cement concrete piles of temporary shoring, for which a cylindrical cavity for accumulation of sandy material was created in the body of the pile by drilling. At the bottom of the pile from the pit, artificial holes were created for self-healing. Results: it was experimentally confirmed that when using sand from the quarry № 5, the through cracks in the diaphragm of the dam of Nizhne-Bureyskaya HPP will be completely colmatized by the soil of the healing layer located in front of the top face of the diaphragm. The sand from the quarry № 5 can be used as a material of the contact layer that provides self-healing of cracks in clay-cement concrete diaphragm of the earth dam, and when it is used, it is necessary to control the recommended granulometric composition of sand and ensure absence of lumps of clayish soils. Conclusions: in the field conditions, we obtained the values of hydraulic gradients at which takes place the self-healing of cracks in clay-cement concrete diaphragm of the earth dam. The requirements to granulometric composition of the contact layer in the structure of the earth dam were clarified. Recommendations were developed for quality control of soil when laying the contact layer of the earth dam.

In this article, methods of analysis of the improved designs of roofs of shallow underground structures are considered. Alternative methods to improve structural and technological solutions for covering underground structures arranged in an open manner are proposed. The developed design solutions are characterized by increased manufacturability due to reduction of labor costs owing to the use of low thermal conductivity concrete as a heat-insulating layer, which is monolithically connected during the manufacturing process with external layers of structural concrete because of the successive laying of these layers. To analyze the stress-strain state of roof’s structure and soil massif, a finite element method was used implemented in finite-element software packages. Subject: stress-strain state of structures of roofs of underground constructions built by an open method from different types of concrete with a monolithic bonding of layers. Research objectives: verification of finite element software packages used for analysis of the stress-strain state of soil massifs, as applied to multi-layer structures of roofs with a monolithic bonding of layers. Materials and methods: in our research, we used the methods of computer simulation of the stress-strain state of multi-layer bending structures of roofs from different types of concrete with a monolithic bonding of layers used in shallow underground structures. As for numerical software, the finite element software package ZSOIL was used. Results: in the article, we determine the rational areas of application of roof’s structures for shallow underground structures that are capable of sustaining vertical force loads and pressure from the ground massif. Structural and technological design solutions for roofs of underground structures, including the roofs of underground parking lots attached to the erected building, are characterized by low material consumption and increased manufacturability. Conclusions: for underground structures built in open excavation pits over which there are no aboveground floors, it is recommended to use multi-layer roof with a heat-insulating layer of concrete of low thermal conductivity as an alternative to traditional design solutions. Competitive structural and technological solutions of roofs and floors of shallow underground structures are obtained on the basis of computer simulation of stress-strain state using state-of-the-art finite element software.

Subject: synchronization implies that certain processes are brought to their execution that is either simultaneous or occurring with a constant time interval. However, according to the author’s opinion, substantiated in the article, in the process of integrated development of multifunctional urban environment, the concept of synchronization should be understood more widely, taking into account dimensions of the objects in relation to which the processes under study occur. Research objectives: formation of a coupled three-level model that compares the hierarchy of urban environment development (urban-block - quarter - micro-district) to three different development technologies implemented by various entities of investment and construction activity. Materials and methods: method of comparative analysis. Results: the resulting model, structured in the form of three interrelated subproblems described in the work, is proposed by the author as a tool for analyzing adopted and proposed variants for state participation in the development of multifunctional urban environment. Conclusions: the proposed three-level model of synchronization of the processes of integrated development of multifunctional urban environment adequately reflects economic and other relationships established in this field between the participants of the town-planning activity and can be successfully used.

Subject: the subject of the study is technological parameters of the construction of roof structures with greenery. At present, the problems associated with the study of technical and technological parameters in the design of non-traditional energy-saving engineering systems, as well as their influence on the state of the housing and communal complex, have not been sufficiently studied. Research objectives: in order to reduce the labor costs in the construction of the roofing, reduce the time required to carry out repair and restoration work and ensure the quality of the roof’s operational usability, several variants of inverted roofing with greening were considered, and the best variant of energy-efficient structure and technology of erecting green roofing was identified. For modern buildings, with the use of advanced construction technologies, compliance with criteria of high constructive quality, manufacturability, and durability of building materials must be met. Materials and methods: the research uses methods of mathematical modeling, as well as modeling of technological processes in software environments. Results: based on the analysis of technological characteristics, it is established that among the technological processes and operations with different options for erecting green roofing systems, the best variant is the inverted “green” roofing with the use of modular structures. The labor intensity of erecting this roofing is 47.13 man-days, which is 38 % lower than in alternative versions, and the total duration of the roofing construction is 17 days, which is almost twice less than that in analogous designs. The use of modular technologies in greenery systems, the improvement of technological processes of erection of roofing with greenery systems are aimed at reducing the labor intensity of works and reducing the duration of construction, and in addition, implementation of innovative technologies contributes to an increase of the service life of the roofing and a longer operation of the object of construction (by 20-30 %). Conclusions: the use of rational technologies in the construction of roofing with greenery systems is the most effective solution, as the labor intensity of technological processes is reduced when constructing roofs with greenery systems in comparison with traditional types of roofs, and during the roof operation, the development of functional purpose is ensured.

Subject: methods for predicting the remaining service life of asphalt pavements based on development of pavement’s functional state model and established threshold values of benchmark parameters for each level of pavement degradation. Research objectives: substantiate the method for predicting the remaining service life of asphalt pavements based on the uniformity of their specific heat values. Materials and methods: the application of the uniformity of the specific heat values of pavement and the index of thermophysical uniformity as criterion parameters, was demonstrated. Results: the use of approximating function describing the evolution of the index of thermophysical uniformity to assess the current condition of pavement and to predict its further deterioration is justified; calculation formulas were obtained to determine the remaining service life of pavements. Conclusions: methods for determining the remaining service life of asphalt pavements are proposed. Knowledge of the remaining service life should facilitate strategic decision-making with regard to required road repair and maintenance, and thereby lead to a more efficient use of existing resources.

Foamed glass is one of the most energy efficient construction materials. However, the existing technologies of foamed glass manufacture do not correspond to the principles of green construction because a special sulphate glass is used, produced from natural raw materials, and it causes emission of pollutants at all stages of the life cycle of the material. The resource and energy-saving technology for producing environmentally safe energy-efficient foam glass based on off-grade glass cullet, which is a component of solid municipal waste, has been developed, substantiated and implemented. In solving a particular problem of foam glass production, an algorithm of development of an environmentally safe building material based on or with addition of production and consumption wastes was proposed and approved. This algorithm is consistent with the principles of green construction. Subject: development of the technological scheme of manufacture and recycling of energy efficient cellular material corresponding to the requirements of ecological safety at all stages of its life cycle; proposition of an algorithm that solves the general problem of development of environmentally friendly construction materials and conforms to the principles of green construction. Materials and methods: analysis of existing technical solutions for manufacture and recycling of foam glass from the viewpoint of green construction principles and proposition of alternative environmentally friendly solutions. Results: as a result of elimination of the drawbacks inherent in the existing foam glass at all stages of its life cycle, technical solutions that ensure environmental safety of the material were substantiated. Conclusions: the results can be used for development of construction materials corresponding to the principles of green construction.

Subject: the ways for obtaining the sets of climate data for simulation of air and thermal regime of the building premises and assessment of its annual energy consumption are considered. It is noted that most modern approaches in this field rely on the concept of a “typical year”, and therefore unsuitable for engineering practice as they require the search, accumulation and selection of a large number of climatic parameter values. Research objectives: generalization of probabilistic approach to obtaining the sets of climatic data for the case of a study of annual variation in the average daily temperature of outdoor air and creation of a set of outdoor temperatures during the warm season (cooling period). Materials and methods: in this work, we used the software generation of climatic data sets by Monte Carlo method using a pseudorandom number generator based on a linear congruence algorithm. The regular seasonal variation of outside temperature is accounted for by using the “floating” mathematical expectation and the standard deviation. A numerical model of non-stationary thermal regime of a ventilated room is implemented based on the solution of a system of differential equations of heat conduction and heat transfer for the surfaces of the room. Results: some results of calculation of the current ambient temperature during the year and in the warm season using Monte Carlo method are presented for climatic conditions of Moscow. We performed comparison of the results of estimation of unsteady thermal regime of a ventilated room when using average daily outside air temperatures during a month obtained from climatic data and from the results of computer simulation. Conclusions: we demonstrated the principal coincidence of the statistical distribution of outside air temperature and temperature variation of the internal air for both compared variants. It is noted that Monte Carlo simulation gives the results that are indistinguishable, from the standpoint of engineering needs, from the use of a “typical year”, and we revealed the possibility of practical implementation of probabilistic-statistical principle of climate data generation for some calculations that concern the systems of air-conditioning and thermal regime of the building. It is proposed to apply the developed methodology for estimation of the annual energy consumption of buildings and for estimation of efficiency of energy and resource saving.

Subject: the article is devoted to the study of corrosion processes in the water supply pipeline network. Initial growth and spatial orientation of corrosive tubercle deposits in non-coated steel pipes were studied. Experimental data are presented and an analysis of conditions and mechanism of formation of corrosive tubercles in water pipes is carried out. An assumption is made about the effect of flow velocity on the formation, growth and spatial distribution of tubercle deposits on the inner surface of the pipe. Research objectives: study of the mechanism of metal pipes corrosion in the water supply systems; development and experimental verification of the hypothesis of formation of tubercle corrosion deposits in pipelines. Materials and methods: the literature data on morphology and composition of tubercle corrosion deposits is analyzed. An experimental study of the initial stage of steel pipe corrosion under static and dynamic conditions has been carried out. Shape and composition of corrosion deposits on the metal surface were analyzed with the help of scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The rate of corrosion in a steel non-coated pipe in cold tap water was measured. Results: the study of corrosion sediment shows that its formation and properties are significantly influenced by water flow rate. In the static regime, a uniform distribution of the anode and cathode areas, covered with loose sediment, is observed over the entire area of the sample. In the dynamic mode, the sediment is partially or completely removed from sample surface and the corrosion rate increases. The corrosion process proceeds with oxygen and hydrogen depolarization and contribution of hydrogen depolarization is significant. Over the anodic sections, a dense layer forms with magnetite formation during the cathodic reduction of iron hydroxides. The corrosion rate gradually decreases with time. The presence of sediment on the metal surface slows down the corrosion rate. Conclusions: the conducted studies showed that in the presence of water movement, larger anode and cathode areas are formed on non-galvanized steel pipe samples. These areas, in the course of further corrosion, are transformed into tubercles. Formation of two structural elements of future tubercle deposits was experimentally verified. Water flow velocity, along with the electrochemical processes, is a factor that directly influences the tubercle spatial arrangement and growth on the inner surface of the pipe.

Subject: this paper relates to the field of hydrodynamics and scientific foundations of hydraulic engineering construction, and is devoted to investigation of the laminar flow of an incompressible fluid in which two coaxial layers moving together along a cylindrical tube rotate in opposite directions. In literature, this flow is called counter-vortex. Research objectives: improvement of the theoretical model of the counter-vortex laminar flow. In the turbulent range, the flow is characterized by intensive mixing of the moving medium and dissipation of its mechanical energy. Both these properties find practical application: the first one - in technologies that involve mixing of heterogeneous and multiphase media; the second one - for dissipation of mechanical energy of flows of liquids or gases in high-head hydraulic spillways and for suppressing the noise of aircraft engines and propellers. Theoretical study of laminar counter-vortex flows with oppositely rotating layers allows us to reveal the general physical laws of their hydrodynamics. Materials and methods: the theoretical model of the laminar counter-vortex flow is based on the method of expansion of the Navier-Stokes differential equations into Fourier-Bessel series. The improvement of the theoretical model of the laminar counter-vortex flow consists in elimination of the previously used assumption that the second partial derivative with respect to the axial coordinate on the right-hand side of equation (9) of this article is negligible. Results: a refined theoretical model of the laminar counter-vortex flow is obtained, based on the removal of this assumption. More accurate formulas for calculating the radial-longitudinal distributions of azimuthal and axial velocities in the studied flow are obtained in the form of Fourier-Bessel series or products of these series. The distributions of azimuthal and axial velocities are represented graphically in the form of their profiles. Conclusions: it is shown that taking into account the second partial derivative with respect to the axial coordinate on the right-hand side of equation (9) leads to a more accurate theoretical model of the laminar counter-vortex flow and makes it possible to substantially improve the accuracy of the analytical solution for velocity fields in such flows, namely by more than 2.3 % for small Reynolds numbers (less than Re = 100).