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Vestnik MGSU 2018/11

DOI : 10.22227/1997-0935.2018.11

Articles count - 11

Pages - 1418

Architecture and Urban Planning. Reconstruction and Refurbishment

Analysis of heat losses in stoves. The real efficiency of the furnace

  • Shevyakov Vladimir V. - Candidate of Technical Sciences, independent researcher; ORCID 0000-0001-5946-2742..

Pages 1296-1304

Introduction. An approach to the development of recommendations on the choice of operating modes of the furnace and of its design parameters is presented. Efficiency of a household stove is a rather broad concept by which the uniform heating of stove surfaces and heat transfer over time, etc. are understood. The ability of the stove to receive heat from burning wood and transfer heat to the room with minimal losses is the technical characteristics, which we will consider. The operation of any furnace is cyclic. Each cycle consists of two parts: the accumulation of heat (the mode of the furnace, the combustion of wood) and the heat transfer to a heated room (the mode of heat release). The furnace furnace mode is characterized by the efficiency of the furnace. Not all the heat left in the furnace is transferred to the room. Part of the heat goes into the foundation and through the valves in the pipe. The estimation of heat losses and the amount of carbon monoxide in a household oven, recommendations for their reduction are given. Materials and methods. A detailed analysis and assessment of heat losses, an estimate of the amount of carbon monoxide in a household oven, and the development of recommendations for their reduction are given. Results. The results of the study and analysis are used to develop ecommendations on the choice of operating modes of the furnace and the choice of its design parameters. Conclusions. The results of the work can be recommended in the development of domestic stoves.

DOI: 10.22227/1997-0935.2018.11.1296-1304

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Increase of strength of partially destroyed wood of monuments of wooden architecture

  • Pokrovskaya Elena N. - Moscow State University of Civil Engineering (National Research University) (MGSU) Doctor of Technical Sciences, Professor, Moscow State University of Civil Engineering (National Research University) (MGSU), 26 Yaroslavskoe shosse, Moscow, 129337, Russian Federation.

Pages 1305-1314

Introduction. Monuments of wooden architecture - an invaluable part of the national culture, they reflect the originality and independence of the national architecture. The problem of preservation of monuments of wooden architecture with the passage of time is becoming increasingly important. Many monuments were burned; some were destroyed due to the loss of structural strength under the influence of humidity, biodestruction, etc. Materials and methods. The samples of partially destroyed wood of the Anglican Church of the city of Arkhangelsk, built in 1833, were studied. The samples were subjected to surface modification with the formation of a two-layer sandwich coating, the first layer of which was various phosphorus-containing flame retardants, and the second layer - polymer composites. As polymer composites, glue based on epoxy resin and polyurethane composition “Akvidur TT” were used. The reactive organophosphorus compounds, capable of forming covalent bonds with wood polymers in the surface layer of partially destroyed wood, were chosen as flame retardants. Modified samples were subjected to physicochemical studies to determine the strength, fire resistance, hydrophobicity. The strength of the modified samples was compared with the strength of the untreated samples of partially destroyed wood of the Anglican Church of Arkhangelsk. The appearance of covalent bonds between the wood and the modifier was determined by Fourier-transform spectroscopy. Results. Surface modification of the samples of the monument increased the strength of wood by 2-2.5 times, reduced water absorption by 3 times, reduced the loss of mass during combustion according to GOST 27484-87 to 5.0-6.4 %. Conclusions. The study solves the urgent problem of preservation of monuments of wooden architecture by increasing the strength of partially destroyed wood, as well as giving it fire resistance, hydrophobicity and biostability in carrying out restoration work.

DOI: 10.22227/1997-0935.2018.11.1305-1314

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Construction Process Technology. Construction Economics, Administration and Management

Ecological and economic aspects of planning of placing and designing of industrial targets on processing, recyclings, to neutralisation of a waste

  • Tskhovrebov Eduard S. - Research Institute “Environmental Industrial Policy Centre” (EIPC) Candidate of Economic Sciences, Associate Professor, Research Institute “Environmental Industrial Policy Centre” (EIPC), 42 Olympic avenue, 141018, Mytishchi, Russian Federation.

Pages 1326-1340

Introduction. Presented the approach to is working out of methodological bases, a scientifically-methodical substantiation of legal regulation, organizational-administrative, economic principles of placing, designing of an infrastructure of the industry on processing, recyclings, to neutralisation of a waste. For today our country considerably lags behind the leading European countries on effective realisation of a universal principle 3R (prevention of formation of a waste, a reuse, processing in secondary resources). One of principal causes - absence of economically effective control system of a waste and secondary resources. Leaving at the present stage of development of Russia on one of the first places a problem of annually increasing volumes of a formed and buried industrial and household waste and directly the environmental contamination connected with it, accumulation of an ecological damage (harm) forms an actual problem of development of an industrially-transport infrastructure of the reference with a waste and secondary resources both at regional and inter-regional levels, and on the scale of all country. The given problem dictates necessity of search of the new scientifically and practically proved scientifically-methodological practically proved scientifically-methodological, methodical approaches and decisions to optimum planning of placing and designing of an industrially-transport infrastructure of the reference with a waste, including the organisation of management, regulation, the account, monitoring and the control of gathering, accumulation, transportation, processing, recycling, neutralisation of a waste, to development of methods of savings of resources and energy, to search of ways ecologically admissible, technically and technologically possible, economically expedient increase of level of taken secondary material resources from a waste. Materials and methods. As materials for carrying out of scientific research serve: legislative base, legal certificates, standards, methodical recommendations, design and the specifications and technical documentation in the field of the reference with a waste, the published data and materials of scientific domestic and foreign researches on the given subjects. Methods of scientific research are based on use factorial, comparative, kvalimetric the analysis, the theory of restrictions, expert methods of an estimation of indicators. Results. Scientifically proved offers, methodological approaches to planning of actions for industry development on processing, recycling, neutralisation of the waste. Conclusions. Formation of scientifically-methodological and methodical bases of planning of placing and designing of industrial targets on processing, recyclings, to neutralisation of a waste should be coordinated and include all aspects connected with technical and economic, ecological, is standard-legal, organizational-administrative maintenance of activity and creation of complex system of the reference with a waste and secondary resources within the limits of a course on a sustainable development of the Russian state.

DOI: 10.22227/1997-0935.2018.11.1326-1340

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Construction System Design and Layout Planning. Mechanical Equipment Challenges in Construction

Study of parametric oscillations of viscoelastic cylindrical panel of variable thickness

  • Abdikarimov Rustamkhan A. - Tashkent Institute of Finance Doctor of Physical and Mathematical Sciences, Associate Professor, Tashkent Institute of Finance, 60A A. Temur st., Tashkent, 100000, Uzbekistan.
  • Khodzhaev Dadakhan A. - Tashkent Institute of Irrigation and Agricultural Mechanization Engineers (TIIAME) Candidate of Physical and Mathematical Sciences, Associate Professor, Tashkent Institute of Irrigation and Agricultural Mechanization Engineers (TIIAME), 39 Kary-Niyazov st., Tashkent, 100000, Uzbekistan.
  • Normuminov Bakhodir A. - Tashkent Institute of Irrigation and Agricultural Mechanization Engineers (TIIAME) Senior Lecture, Tashkent Institute of Irrigation and Agricultural Mechanization Engineers (TIIAME), 39 Kary-Niyazov st., Tashkent, 100000, Uzbekistan.
  • Mirsaidov Mirziyod M. - Tashkent Institute of Irrigation and Agricultural Mechanization Engineers (TIIAME) Academician of Academy of Sciences of Uzbekistan, Doctor of Technical Sciences, Professor, Tashkent Institute of Irrigation and Agricultural Mechanization Engineers (TIIAME), 39 Kary-Niyazov st., Tashkent, 100000, Uzbekistan.

Pages 1315-1325

ABSTRACT Introduction. Isotropic viscoelastic cylindrical panels of variable thickness under the effect of a uniformly distributed vibration load applied along one of the parallel sides, resulting in parametric resonance (with certain combinations of eigenfrequencies of vibration and excitation forces) are considered. Materials and methods. It is believed that under the effect of this load, the cylindrical panels undergo the displacements (in particular, deflections) commensurate with their thickness. Based on the classical Kirchhoff-Love hypothesis, a mathematical model of the problem of parametric oscillations of a viscoelastic isotropic cylindrical panel of variable thickness in a geometrically non-linear formulation is constructed. Corresponding nonlinear equations of vibration motion of panels under consideration are derived (in displacements). The technique of the nonlinear problem solution by applying the Bubnov-Galerkin method at polynomial approximation of displacements (and deflection) and a numerical method that uses quadrature formula are proposed. The Koltunov-Rzhanitsyn kernel with three different rheological parameters is chosen as a weakly singular kernel. Results. Parametric oscillations of viscoelastic cylindrical panels of variable thickness under the effect of an external load are investigated. The effect on the domain of dynamic instability of geometric nonlinearity, viscoelastic properties of material, as well as other physical-mechanical and geometric parameters and factors (initial imperfections of the shape, aspect ratios, thickness, boundary conditions, excitation coefficient, rheological parameters) are taken into account. Conclusions. A mathematical model and method have been developed for estimating parametric oscillations of a viscoelastic cylindrical panel of variable thickness, taking into account geometric nonlinearity under the action of periodic loads. The results obtained are in good agreement with the results and data of other authors. The convergence of the Bubnov-Galerkin method is verified.

DOI: 10.22227/1997-0935.2018.11.1315-1325

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Reducing risks in the construction enterprise under strategic leadership of the management

  • Victoria G. Borkovskaya - Moscow State University of Civil Engineering (National Research University) (MGSU) , Moscow State University of Civil Engineering (National Research University) (MGSU), 26 Yaroslavskoe shosse, Moscow, 129337, Russian Federation.

Pages 341-1348

Ntroduction. Discusses the issues of risk reduction with strategic leadership in construction area. We focus on leadership strategy in construction from the perspective of reducing risks (environmental, occupational, enterprises and so on) and costs. In strategic management, one of the general strategies of building enterprise goals is aimed at creating competitive advantages. Using a cost leadership strategy in construction, the company focuses on a wide market and produces large quantities of goods, minimizing costs and offering low prices. Subject of research business leaders in construction, top managers, department heads, with characteristic signs of a leader. Materials and methods. When analyzing the questions posed, methods of system analysis, modeling and synthesis were used. Results. Leadership in construction can develop a strategy to reduce risk and improve processes to also result in minimizing costs. The strategy for reducing risk is to carry out activities that reduce either the probability or the damage, or both, from medium to low, from high to medium or low. It was revealed that in order to achieve high results of the economic and corporate activities of an organization, one cannot hope only for a happy coincidence of circumstances. One of the most important conditions for the successful development of any construction company is the interested personnel and quality of leadership. Each success in construction is the result of the well-coordinated and painstaking work of the whole team, as a single mechanism. The smooth functioning of such a mechanism is ensured by the team, which is formed by the leader. In the context of globalization of markets, it is not enough for the head of an organization to be a leader, in the traditional sense. A modern leader in construction must be an ideologue, strategist and technologist in one person. The presence of a complex of three qualities is a strategic leadership. Conclusion. It is determined that strategic leadership in construction is not a fashionable tendency of the denomination of classical leadership, but an inherent need for long-term planning of the organization’s activities. One of the main consequences of strategic leadership in construction is the reduction of enterprise risks to facilitate and maybe guarantee the success of a construction company.

DOI: 10.22227/1997-0935.2018.11.1341-1348

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Construction Material Engineering

Evaluation of the influence of finishing coatings on the change of the moisture regime of the gaz-concrete fencing construction

  • Loganina Valentina I. - Penza State University of Architecture and Construction Doctor of Technical Sciences, Professor, Head of Department of Quality Management and Technology of Construction Production, Penza State University of Architecture and Construction, 28 Germana Titova st., Penza, 440028, Russian Federation.
  • Frolov Mikhail V. - Penza State University of Architecture and Construction graduate student of the Department of the Quality Management and Technology of Construction Production, Penza State University of Architecture and Construction, 28 Germana Titova st., Penza, 440028, Russian Federation.
  • Skachkov Yuri P. - Penza State University of Architecture and Construction Doctor of Technical Sciences, Professor, Rector, Penza State University of Architecture and Construction, Penza State University of Architecture and Construction, 28 Germana Titova st., Penza, 440028, Russian Federation.

Pages 1349-1356

Introduction. Provides information about the moisture regime of the building structure of aerated concrete in the presence of finishing coatings. Plaster coatings based on dry construction mixtures Knauf Grunband, developed by the authors of lime compositions using hollow glass microspheres and ash aluminosilicate microspheres, cement-sand compositions were considered. Materials and methods. Aerated concrete blocks of various grades were used as the main material: D350, D400, D500, D600. Cement-slag plaster was adopted as an internal finishing layer for all variants. The outer surface of the wall is finished with Knauf Grunband dry construction mixtures, as well as developed lime compounds using hollow glass microspheres and ash aluminosilicate microspheres. The outside air temperature was determined, at which moisture condensation begins in the wall and on the border of the finishing layer - aerated concrete wall Results. When using Knauf Grunband plaster composition as finishing, the temperature of the onset of condensation drops to -9.0 °C. When using the developed DBM, obtained using hollow glass microspheres and ash aluminosilicate microspheres as fillers, the temperature of the onset of condensation decreases to -11.4 and -11.9 °С, respectively. Condensation at the border of the finishing coating - aerated concrete begins at a temperature of -2.4 °C, in a fencing structure of a gas concrete of the mark D400 with a plaster coating of a density of 1800 kg/m3 - at a temperature of -3.8 °C, and in aerated D400 grade with a plaster density of 1100 kg/m3 -at a temperature of -5.5 °C. Conclusions. The conducted studies prove that due to the use of heat-insulating DBM for finishing gas-concrete blocks of the D300-D600 grades, which allow to obtain coatings with a density of less than 800 kg/m3, the outdoor air temperature decreases, at which the moisture in the wall starts. Also, due to the use of the developed coatings, the external air temperature is significantly reduced, at which the finishing coating - aerated concrete begins at the border. This will minimize the amount of condensable moisture in the thickness of the enclosing structure and extend the service life of both the finishing coating and the wall as a whole.

DOI: 10.22227/1997-0935.2018.11.1349-1356

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Heuristic approach to solving two-criterion problem of optimization of composite materials

  • Afonin Victor V. - National Research Ogarev Mordovia State University (MRSU) Candidate of Technical Science, Associate Professor, Associate Professor of Department of Automated Systems of Information Processing and Management, National Research Ogarev Mordovia State University (MRSU), 68 Bolshevistskaya st., Saransk, 430005, Russian Federation.
  • Erofeeva Irina V. - Research Institute of Building Physics of the Russian Academy of Architecture and Building Sciences (NIISF RAASN) Junior Researcher, Research Institute of Building Physics, Research Institute of Building Physics of the Russian Academy of Architecture and Building Sciences (NIISF RAASN), 21 Locomotive travel, Moscow, 127238, Russian Federation.
  • Fedortsov Vladislav A. - National Research Ogarev Mordovia State University (MRSU) Postgraduate Student, National Research Ogarev Mordovia State University (MRSU), 68 Bolshevistskaya st., Saransk, 430005, Russian Federation.
  • Emelyanov Denis V. - National Research Ogarev Mordovia State University (MRSU) Candidate of Technical Science, Associate Professor, Department of Building Materials and Technologies, National Research Ogarev Mordovia State University (MRSU), 68 Bolshevistskaya st., Saransk, 430005, Russian Federation.
  • Podzhivotov Nikolay Y. - All-Russian Scientific Research Institute of Aviation Materials (VIAM) Candidate of Science (Technics), Senior Researcher, Laboratory of Strength and Reliability of Aircraft Materials, All-Russian Scientific Research Institute of Aviation Materials (VIAM), 17 Radio st., Moscow, 105055, Russian Federation.

Pages 1357-1366

Introduction. Presented the approach to optimal choice of materials, in particular, composite materials. An important task of modern materials science is the development of effective composite materials, which is associated with numerous scientific studies in this area and the search for materials with certain additives in order to obtain the necessary properties. First of all, it is an indicator of the hardness of the composite material. Materials and methods. Traditionally, different compositions are studied and property values are analyzed, and experimental results are processed in different ways. Multi-criteria optimization occupies a special place in the theory of optimization of objects, which include composite materials, in particular concrete with various additives. For this it is necessary to formulate a multicriteria optimality problem, in particular a two-criterion minimization problem. Results. Two heuristic optimization criteria are considered, according to which a vector criterion is formed, which allows to carry out the selection of composite materials from experimental data at its minimization. Vector criterion connects the change of the studied properties of the composite material with the simultaneous preference for the choice of the composition that optimizes the given criterion of optimality. The basis of the construction of the optimization scheme of choice of materials is a piecewise linear approximation of the test results, which allows to determine the scalar criteria on the basis of which the vector optimization criterion is constructed. To demonstrate two-criterion optimization, the results of experiments for cement composites exposed under the cyclic influence of negative and positive temperatures are considered. The search for the optimal composition in terms of hardness from the time of exposure. Conclusions. The proposed approach of optimal choice of materials, in particular, composite materials, can be tested on large numbers of test samples, or to automate calculations. This approach has a certain heuristic character. But its practical significance is confirmed by the expert evaluation of the quality of composite materials due to the existing methods of evaluation of materials, for example, in terms of changes in its hardness.

DOI: 10.22227/1997-0935.2018.11.1357-1366

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Rotor-screw systems for preparation of cement clinker

  • Serga Georgi V. - Kuban State Agrarian University named after I.T. Trubilin (Kuban SAU) Doctor of Technical Sciences, Professor, Head of the Department of Descriptive Geometry and Graphics, Kuban State Agrarian University named after I.T. Trubilin (Kuban SAU), 13 Kalinina st., Krasnodar, 350044, Russian Federation.
  • Belokur Kirill A. - Kuban State Agrarian University named after I.T. Trubilin (Kuban SAU) andidate of Technical Sciences, Associate Professor, Dean of the Faculty of Land Management, Kuban State Agrarian University named after I.T. Trubilin (Kuban SAU), 13 Kalinina st., Krasnodar, 350044, Russian Federation.
  • Khvostik Еduard А. - Kuban State Agrarian University named after I.T. Trubilin (Kuban SAU) Master student of the Faculty of Architecture and Construction, Kuban State Agrarian University named after I.T. Trubilin (Kuban SAU), 13 Kalinina st., Krasnodar, 350044, Russian Federation.

Pages 1367-1385

Introduction. Presents an approach to research rotor-screw systems for cement clinker production. Main tasks in the production of cement clinker in a rotary furnace whose housing is horizontal are reducing the size, increasing productivity, simplifying the operation, reducing the energy intensity. Considered equipment construction, allowing to solve these problems. Materials and method. A comprehensive research method was used in the work. Analytical methods have made it possible to create a methodology for calculating the screw housing of a rotary kiln for the preparation of cement clinker. The search for designs of screw housings was performed using descriptive geometry and engineering graphics using the Kompas-3D software package. An analytical study of physical phenomena occurring in the contact zone of cement clinker granules used an apparatus of dimensionless kinematic functions (similarity invariants) and dimensional analysis. The application of similarity invariants made it possible to investigate not just one case, but an infinite number of different cases, united by some commonness of properties. Experimental studies were carried out on models to confirm the validity of theoretical positions and analytical dependencies. Results. The results of research of rotor-screw systems for cement clinker production are presented. The designs of screw housings for rotary kilns are proposed. They, in comparison with known designs of a similar purpose, significantly increase productivity, reduce the dimensions, weight of furnaces and power consumption, due to their implementation with screw grooves. Conclusions. Technical solutions protected by 17 patents of the Russian Federation are offered. The proposed technologies and design schemes of equipment are designed to increase the rotational speed of the screw-like housing at the rotary kiln several times, which will give us an increase in productivity, while reducing the dimensions of the rotary kiln. The novelty of the research is to obtain dependencies for calculating the speed of longitudinal movement of cement clinker granules in the screw casing of rotary kilns, as well as to create a new classification of rotary-screw systems for the preparation of cement clinker.

DOI: 10.22227/1997-0935.2018.11.1367-1385

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HYDRAULICS. ENGINEERING HYDROLOGY. HYDRAULIC ENGINEERING

Ecological problems of the Tyrnyauzsky tailings dam on the river Gizhgit

  • Gegiev Kasbolat A. - High-Mountain Geophysical Institute (HMGI) Candidate of Technical Sciences, Head of the laboratory of mountain hydrology, High-Mountain Geophysical Institute (HMGI), 2 Lenin prospect, Nalchik, 360030, KBR, Russian Federation.
  • Sherkhov Andzor Kh. - High-Mountain Geophysical Institute (HMGI) Candidate of Physical and Mathematical Sciences, Head of the laboratory of geoecological monitoring of the Department of environmental research, High-Mountain Geophysical Institute (HMGI), 2 Lenin prospect, Nalchik, 360030, KBR, Russian Federation.
  • Gergokova Zayna J. - High-Mountain Geophysical Institute (HMGI) research fellow, High-Mountain Geophysical Institute (HMGI), 2 Lenin prospect, Nalchik, 360030, KBR, Russian Federation.
  • Anahaev Kaisin K. - Moscow State University of Civil Engineering (National Research University) (MGSU) master student, Moscow State University of Civil Engineering (National Research University) (MGSU), 26 Yaroslavskoe shosse, Moscow, 129337, Russian Federation.

Pages 1386-1394

Introduction. In article the current state of the store of industrial wastes of the former Tyrnyauz tungsten-molybdenum combine - the Tyrnyauz tailing dump 168 m high which is the highest construction of this kind in our country is considered. The tailings dam is located in line with the mountain river Gizhgit which drain is taken away on a special by-pass tunnel. In the last decades in the basin of this river there is an active development erozionno-landslide processes with formation of mud streams on the bed of the river. Due to Tyrnyauz tungsten-molybdenum combine disorder the considered tailings dam was almost ownerless and the condition of its safety causes big fears now. Materials and methods. The description of the main hydraulic engineering constructions of object which analysis of a state shows susceptibility to their negative impact of water mud streams of the river Gizhgit is given. Results. Special danger is constituted by possible “obstruction” of a by-pass tunnel (an internal collapse of rocks, blockage by torrential carrying out, etc.) with the subsequent dumping of flood expenses of the river in the tailings dam that will create direct threat of its break with serious economic and ecological consequences not only for basins of the rivers Gizhgit and Baksan, but also the Terek River to the Caspian Sea. Conclusions. The scenario of possible development of accident of the tailings dam in the conditions of the admission of water and torrential expenses of this river, and also necessary organizational and technical recommendations about ensuring its safe operation is provided.

DOI: 10.22227/1997-0935.2018.11.1386-1394

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Staged construction of a rockfill dam is the way of regulating the reinforced concrete face stress-strain state

  • Podvysotckii Aleksei A. - Mosoblgidroproekt Candidate of Technical Sciences, Head of Hydrotechnical Department, Mosoblgidroproekt, 1 Energetikov st., Dedovsk, 143532, Russian Federation.
  • Sainov Mikhail P. - Moscow State University of Civil Engineering (National Research University) (MGSU) Candidate of Technical Sciences, Associate Professor, Associate Professor of Department of Hydraulics and Hydraulic Engineering, Moscow State University of Civil Engineering (National Research University) (MGSU), 26 Yaroslavskoe shosse, Moscow, 129337, Russian Federation.
  • Soroka Vladislav B. - SpetsNovostroy engineer, SpetsNovostroy, 20 Communal quarter, Krasnogorsk, 143405, Russian Federation.
  • Dogonov Mark L. - Moscow State University of Civil Engineering (National Research University) (MGSU) graduate student, Moscow State University of Civil Engineering (National Research University) (MGSU), 26 Yaroslavskoe shosse, Moscow, 129337, Russian Federation.

Pages 1395-1406

Introduction. Presented the approach to studies of the impact of a rockfill dam staged construction on the reinforced concrete face SSS. Experience in construction of reinforced concrete face rockfill dams (CFRD) shows that at perception of hydrostatic pressure the integrity of the seepage-control element may be broken. By the results of mathematical modeling it was revealed that the tensile stresses appearing in the face concrete may exceed concrete design tensile strength. The causes of appearing tensile stresses are bending deformations and the face longitudinal extension. The urgent issue is selection of the way of improving the stress-strain state (SSS) of the face to provide its safe operation as a seepage-control element. Materials and methods. The studies were conducted on the example of a 100 m high dam with the aid of numerical modeling. Two cases were considered: in the first case the dam was constructed in one stage, in the other in two stages. Rockfill is considered as a lineally deformed material, but computations were conducted for a wide range of the soil linear deformation modulus: from 60 to 480 МPа. Steel reinforcement was considered in the face. Results. Longitudinal stresses in a reinforced concrete face were compared for two cases of the dam staged construction. Analysis was fulfilled with determination of the longitudinal force and bending moment appearing in the face. The obtained maximum values of tensile longitudinal stresses in the face were compared for two cases. Conclusion. It was revealed that construction and loading of the dam by stages on the whole is favorable for the face stress-strain state. The second-stage dam weight transfers to the first-stage face the compressive longitudinal force, which permits decreasing tensile stresses in it. Bending moments in the face vary insignificantly and even may increase to some extent by value. Nevertheless, at dam construction and reservoir filling in 2 stages the maximum values of tensile stresses in the face concrete decrease, therefore, such construction sequence contributes to enhancing safety of the dam seepage-control element.

DOI: 10.22227/1997-0935.2018.11.1395-1406

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Determination of the temperature field and thermal stress state of the massive of stacked concrete by finite element method

  • Aniskin Nikolay A. - Moscow State University of Civil Engineering (National Research University) (MGSU) Doctor of Technical Sciences, Professor, Department of Hydraulics and hydraulic engineering, Moscow State University of Civil Engineering (National Research University) (MGSU), 26 Yaroslavskoe shosse, Moscow, 129337, Russian Federation.
  • Nguyen Trong Chuc - Moscow State University of Civil Engineering (National Research University) (MGSU) postgraduate student, Department of Hydraulics and hydraulic engineering, Moscow State University of Civil Engineering (National Research University) (MGSU), 26 Yaroslavskoe shosse, Moscow, 129337, Russian Federation.
  • Bryansky Ilya A. - Moscow State University of Civil Engineering (National Research University) (MGSU) postgraduate student, Department of Hydraulics and hydraulic engineering, Moscow State University of Civil Engineering (National Research University) (MGSU), 26 Yaroslavskoe shosse, Moscow, 129337, Russian Federation.
  • Dam Huu Hung - Moscow State University of Civil Engineering (National Research University) (MGSU) Master of the Department of Soil mechanics and geotechnics, Moscow State University of Civil Engineering (National Research University) (MGSU), 26 Yaroslavskoe shosse, Moscow, 129337, Russian Federation.

Pages 1407-1418

Introduction. Energy and hydraulic concrete structures, bridge structures, foundations of buildings are built with concrete blocks. Concreting of such massive structures is accompanied by the phenomenon of exothermic heating of the structure caused by the process of cement hydration. The heat released in such massive blocks under natural conditions is very slowly removed from the structure. Quite often, between the central part of the massif and its surface, there is a significant temperature drop. In the case of reaching a critical value of the temperature difference, temperature cracks occur that violate the solidity of the structure. For a preliminary assessment of the possibility of cracking and the development of measures to eliminate it, it is necessary to solve the temperature problem and the problem of determining the thermal stress state. This problem has long been in the center of attention of specialists and a large number of studies are devoted to it. Developed and used a large number of methods for solving these problems. However, in view of the great complexity of the task to be solved, caused by a multitude of operating factors and conditions, the complexity of the structures and the increased requirements for the safety of structures, the task of determining the temperature regime and the thermally stressed state of the erected concrete massif is still very relevant today. This paper presents some results of investigations in this direction, performed on the basis of the finite element method. An erected concrete block is considered, for which a non-stationary temperature problem is solved successively and the resulting temperature stresses are determined. The variants of block laying at different external temperature influences are considered. Materials and methods. The study was performed on the basis of the finite element method (FEM) using the Ansys software. Results. For the considered array concrete obtained temperature distribution and thermal stresses over time from the moment of packing to obtain a sufficient structural strength (about 30 days). On the basis of criteria assesses the possible occurrence of thermal cracks. Conclusions. Based on the numerical solution of the problems of determining the temperature regime and the thermally stressed state of the concrete block using the Ansys software complex, a detailed picture of the spatial no stationary state of the structural element, the concrete block, as part of a massive structure, has been obtained.

DOI: 10.22227/1997-0935.2018.11.1407-1418

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