Introduction.

One of the possible factors acting on the stability of the slopes of an earth dam is the change of water levels in the reservoir or the downstream reservoir. A hazardous event can be a rapid drawdown of the reservoir due to, for example, an emergency or a technological necessity. Examples of collapse of ground dam slopes caused by changes in water level in the reservoir are given, as well as the results of estimation of the effect of reservoir drawdown on the stability of the upstream slope. A homogeneous enclosing dam made of loam on a non-rock base with a height of 29 m and upper and lower slopes of 1:3.5 was considered. The research was conducted for two cases of drawdown: slow drawdown with the rate of vertical water level decrease v = 0.25 m/day and fast (emergency) drawdown with the rate of v = 4.4 m/day.

Materials and methods.

Calculations of filtration of soil dam for steady and unsteady modes and assessment of stability of the dam slope are carried out by numerical method of finite elements using PLAXIS software package. The research statement and theoretical foundations, laid in calculations of filtration and stability of slopes are given.

Results.

Researches have shown that at decrease in a water level of a reservoir with the big speed the danger of infringement of stability of a slope increases.

Conclusions.

According to the practice of designing, the evaluation of change in the upper slope stability coefficient of the uniform ground protecting dike taking into account decrease of the water level in the reservoir taking into account filtration forces of unsteady filtration has been carried out. Variants with different rates of drawdown are considered. It is established that at high rates of drawdown the coefficient of slope stability decreases. The obtained results testify to necessity of taking into account filtration forces of unsteady filtration in evaluation of slope stability when designing homogeneous dams made of low-permeable soils.

Introduction.

Calculation studies have shown that due to the long-term operation of hydraulic structures of the sluice, opening of horizontal and vertical construction joints, as well as corrosion of reinforcement at the rear edge of the reinforced concrete wall of the sluice in the areas of horizontal construction joints, the bearing capacity of the structure as a whole is reduced. In this regard, it is necessary to strengthen the structure, the methodology of which is given in this study.

Materials and methods.

The analysis of scientific and technical documentation has been made, instrumental examination of the state of structures has been carried out, a spatial mathematical model has been developed on the basis of the finite-element method. Multivariant calculated researches of the actual stressed-strained state (SSS) of structures have been made. Calculation studies of the SSS structures were performed taking into account the reinforcement of prestressed basalt composite reinforcement (BCR).

Results.

Visual and instrumental inspection showed a presence of cracking on the front face of the reinforced concrete wall of the sluice chamber. Modeling of the actual state of SSS structures is performed, according to the results of calculations, a scheme for strengthening structures of prestressed BCR is proposed and justified.

Conclusions.

As a result of the calculated studies of the deflected stresses, the occurrence of cracks and opening of horizontal and vertical construction joints in the reinforced concrete structure of the sluice chamber wall was confirmed. At the same time, taking into account corrosion of reinforcement at the rear edge of the sluice’s reinforced concrete wall in the areas of horizontal construction joints, stresses in it reach the design resistance of the reinforcement of class A-II. In order to ensure further safe operation of the structures, the scheme of strengthening the structures with prestressed BCR has been proposed and substantiated.

Introduction.

A set of calculations validating the conditions of limit states is to accompany the design of buildings and structures. Calculations of standard and non-standard combinations of loads and impacts are performed. Special loads include temperature effects from explosions and fires. Such effects greatly reduce the bearing capacity of metal structures. To protect metal structures from temperature effects, optimally selected fire proofing materials (varnishes, paints, various types of cladding) should be used. Numerical calculation methods allow analyzing the performance of building structures, exposed to temperature effects, and help select the necessary characteristics and thicknesses of fire proofing materials.

Materials and methods.

A metal hinged beam is used to analyze the influence of fire proofing, or lining made of fire-resistant gypsum sheets (FRGSh). Analytical and numerical methods of calculations were used to obtain the fire resistance limit of beams with cladding. The analytical method is based on the laboratory studies of fire resistance, as a result of which nomograms were obtained. The numerical method is implemented by Lira 10.12 software package.

Results.

Analytical and numerical methods were used to identify the fire-resistance limits for a beam that had FRGSh cladding. Temperature field mosaics in the elements along the thickness of the structure, as well as graphs of temperature changes and temperature fields in time were obtained using the numerical method. The obtained results showed good convergence.

Conclusions.

The use of numerical methods makes it possible to quickly and optimally select the required thickness of fire proofing for a steel structure. Calculation results are highly dependent on the characteristics of the materials in question, as well as the heat transfer environment.

Introduction.

The author analyzes principal relevant state programmes dealing with housing construction. Researchers specializing in different areas of knowledge focus on the problem of preservation and, if possible, improvement of sanitary and hygienic characteristics of housing construction. It is the maintenance of sufficient values of pre-set indicators and their well-organized control can guarantee comfortable and safe living conditions.

Materials and methods.

The step-by-step analysis was performed and the principal official documents were subsequently compared to get an exhaustive idea of the evolution of sanitary and hygienic standardization in the housing construction.

Results.

The analysis of the pre-revolutionary legislation and fundamental materials on housing construction has revealed that the main task of standardization was to prevent urban fires and ensure the adherence to private property rights. At this stage, sanitary engineers issued their first proposals concerning lighting, insolation, and ventilation standards. Immediately after the revolution, standardization was applied to distribute the available housing stock. Mass housing construction standards needed revisions as new construction projects were launched. The predominance of low-rise construction projects pre-set the development and approval of standards applicable to this type of buildings. Later these norms were applied to the urban construction of residential buildings. Archival materials provided more information about the development and adoption of the main legislative acts in this area.

Conclusions.

Conclusions are drawn about the key role of sanitary inspectors in the development of basic sanitary and hygienic requirements in housing construction. Only their status of national legislative acts can ensure their compliance in the construction industry. At the present stage, the preservation of these standards is the only way to ensure safe living conditions in terms of numerous urban multi-storey construction projects.

Introduction.

Problems of waste gas heat recovery are relevant in the course production activities. Secondary thermal energy resources are the most widely spread type of energy waste. Efficient recovery of waste heat will reduce energy costs. The building of a cafeteria, that has a water-heating waste heat boiler (WHB) represents a widely spread type of industrial buildings in eastern countries, where hot water and heating can be provided by using heat waste recovered from groups of tandoor furnaces. The purpose of the research is to study unsteady convective flows of heat passing through the pipe of a tandoor heat exchanger and to develop a simple design of a small-sized, easy to manufacture, economical and safe model of a water heating device for the needs of the national economy.

Materials and methods.

The research is based on a comprehensive methodology employed to study, analyze and generalize thermophysical processes based on the study of convective unsteady heat flows in heat exchanger pipes of tandoor furnaces.

Results.

The research result represents higher thermal efficiency of the WHB installed in the building of a cafeteria due to the heating, accumulation and heat transfer by vertical finned steel heat-exchanger pipes in the cylindrical boiler in the course of convective heating by the outlet gas used as the heat carrier without returning heat to the water heating boiler.

Conclusions.

The cafeteria building has scientifically and practically grounded design of a WHB tandoor group, which is a vertical cylindrical tank filled with water, in which vertical outlet heat exchange pipes are placed. Heat, emitted during the operation of tandoors, is used to bake flatbreads and bread by burning wood, coal, natural gas or electric heaters. This heat heats boiler sections to supply hot water to consumers and heat the building premises. The method of finned pipes extends the field of application of the device, increasing the coefficient of heat capacity and heat exchange, as well as the capacity of equipment.

Introduction.

The study of heat exchange in cooled combustion chambers and the influence of various factors on its intensity is a complex and relevant task. The analysis of theoretical and experimental data on heat exchange in combustion chambers of various plants has proven that current methods fail to take into account features of heat exchange in furnaces, having small geometric dimensions and, therefore, they cannot be used for their thermal calculation.

Materials and methods.

The author presents the experiments and the results of their generalization performed using the criterial equation. Generalization results are of great importance for analyzing heat transfer processes and the thermal analysis of cooled combustion chambers of small capacity heat generators. The contribution of radiative and convective components to complex heat exchange processes in combustion chambers of low-capacity boilers is evaluated using this generalized dependence. The author has identified qualitative and quantitative dependence of integral radiative and convective heat exchange on the main factors of operation of small combustion chambers.

Results.

The author has obtained generalizing criterial dependence that makes it possible to evaluate the contribution of radiative and convective components to complex heat exchange in combustion chambers of low-capacity boilers.

Conclusions.

The generalized criterial dependence, obtained by the author, can be used to identify the qualitative and quantitative dependence of integral radiative and convective heat transfer on the main geometric, physical and performance factors of operation of small capacity furnace chambers. The assessment of reliability of the experimental data, obtained by the author, has shown that the value of the limiting mean square error of determining the value of integral heat transfer Kh.t will be 3.24 %. For all experiments, the deviation of the calculated data from the experimental results with a 95 % probability does not go beyond the confidence interval of ±9.52 %.

Introduction.

The purpose of the research is to establish the criterion for assessing the pipeline operation efficiency and verify the accuracy of hydraulic design of metal pipes that have internal deposits.

Materials and methods.

The authors provide calculated dependences to determine the values of the characteristics of the hydraulic potential of metal pipes having internal deposits. A specific case is employed to compare the characteristics of new pipes and pipes having different thicknesses of the layer of internal deposits. The percent discrepancy between pipe characteristics is provided.

Results.

The authors recommend evaluating the accuracy of the hydraulic design of water supply and sewerage networks having internal deposits in reliance on the value of the operation efficiency coefficient for water supply or sewerage networks. The authors offer a formula derived to determine the value of the efficiency coefficient for the operation of water supply and sewerage networks having internal deposits on inside walls of a pipe. The authors suggest systematizing the hydraulic design of metal water supply and sewerage networks that are made of metal and have deposits on the inside of pipe walls by taking into account the thickness of the layer of internal deposits, characterized by the value of the network operation efficiency coefficient.

Conclusions.

Systematization of hydraulic design of water supply and sewerage networks that are made of metal and have deposits on the inside of pipe walls allows for the acceptable accuracy of its hydraulic design that takes account of the actual value of the coefficient of efficiency of pipeline operation Kef, taking into account the value of actual thickness of deposit layer σact. In other words, systematization of hydraulic design of water supply and sewerage networks, having deposits on the inside surface of metal pipes, is based on the value of their efficiency coefficient Kef, that takes into account the actual hydraulic potential of pipes (pipelines) depending on the layer of internal deposits σact.

Introduction.

Building information modeling is key to the digital transformation of the construction industry. By maintaining a transparent and continuous flow of information between all stakeholders, BIM facilitates their collaboration at various stages of a project. This leads to significant efficiency gains at lower costs, faster delivery with fewer inaccuracies and delays, better business opportunities, and lower emissions and waste. The purpose of the study is to identify patterns in the formation of new industry-wide information processes and to formulate the main barriers to their implementation in the project practice.

Materials and methods.

The author studied the scholarly publications of domestic and foreign researchers. Since this scope of problems was formulated in the recent decade, materials, published during this period, were considered. Theoretical methods of research were employed: analysis, which allowed the author to break down an extensive information base on the EU countries; classification, which made it possible to identify the main levers for implementing new technologies; analogy, which identified similarities in the development of innovations; synthesis, which generated a general idea of the stages of forming new phenomena in the design of construction projects.

Results.

The author made a comparative analysis of the introduction of new technologies in the EU countries depending on the centre-periphery patterns, drew a parallel between the information processes in Russia and European. He also formulated the main drivers of the introduction of innovative development in the construction sector and decelerating factors based on a 10-year history of the implementation of BIM in European countries.

Conclusions.

The implementation of BIM in the construction sector is often limited. The main barriers are related to interoperability, compliance for all users, workflow changes, legal issues and training, and the emergence of new rights and responsibilities.

Introduction.

Building Information Modeling (BIM) and modular construction are modern technologies that ensure the development of the construction industry. Despite certain weaknesses, both areas have strong prospects today. However, the consequences of integrating these technologies into design have not been sufficiently investigated. Therefore, it is advisable to study the total potential effectiveness of information modeling and modular construction technologies, if applied in combination. Hence, the purpose of this work is to apply information modeling tools to a particular construction facility to identify the effectiveness of design based on prefabricated modular elements. It is necessary to solve the following tasks to achieve this purpose: development of performance evaluation criteria, design of an information model based on prefabricated modular elements, comparison of two alternative facilities, drawing conclusions based on the results of the work.

Materials and methods.

The study is based on a comparative analysis of technical and economic indicators of two alternative facilities, or buildings of data processing centres, whose design documents were developed using modular and traditional approaches. The efficiency analysis is based on the values of design evaluation criteria to be compared. At the same time, the process of designing an information model of a facility, made of prefabricated elements, is considered.

Results.

As a result, the efficiency assessment of the design based on prefabricated modular elements is presented: a similar facility, whose design documentation was developed in the traditional way, is employed to conduct a comparative analysis. The author compares basic evaluation characteristics to the design developed using two different design concepts. At the same time, the author presents an information model, developed using modular design with account taken of the most recent theoretical and practical data available in this area.

Conclusions.

The proposed method of evaluating the design efficiency, based on prefabricated modular elements, demonstrates the obvious advantage of the modular method in terms of the facilities under consideration. At the same time, the information model of a facility is demonstrated, aspects of modular design are presented; weaknesses, further development and efficiency improvement trends are identified.