The article is devoted to mathematical modeling of construction of underwater tunnels intended for subway. This type of tunnels can also be used as railway and road tunnels. The most interesting are underwater tunnels-bridges and floating tunnels, but the most perspective and most frequent are tunnels located at the bottom of water barrier.

Keywords: underwater tunnel, subway, finite element method, leave section method, mathematical modeling, construction technology stages, transport tunnel, stress-strain state

The results of research of engineering solutions for ventilation of swimming pools based on mathematical modeling taking into account real thermal loads and moisture releases are presented. The analysis of air distribution options in rooms with swimming pools for various purposes – a public swimming pool, a SPA complex and a sports pool with bleachers for spectators. Based on the results obtained in the form of distribution fields of the parameters of the air environment, the necessary changes in the schemes of the organization of air exchange are revealed. If the parameters deviate from the normalized values, recommendations have been developed to improve the state of the microclimate. These temperature distributions allow us to conclude that the air temperature near the surfaces of external fences meets the requirements that ensure their safety. conclusions on the compliance of the obtained results with the required parameters of the microclimate for rooms with high relative humidity.

Keywords: Swimming pool, ventilation, heat, moisture, air distribution, microclimate, air environment, numerical modeling

Highways are a fairly significant part of the Iraqi transport system, characterized by increased accidents on the roads. Analysis of the causes of accidents showed their main cause – speeding cars in conditions of increased slipperiness and destruction of the road surface. The influence of the coefficient of adhesion and the degree of destruction of the roadway on the risk of an accident is investigated. Measures to reduce accidents on the roads of the republic are proposed.

Keywords: road safety, the risk of an accident, the coefficient of adhesion, the destruction of the coating, accident analysis, road repairs, the causes of increased accidents

The issues of developing a project for strengthening the building structures of a cable overpass after an emergency (accident) are discussed. On a real example, a description of the accident is given, the performance of work on the ghost of structures to the standard state is illustrated. The article was written on the basis of the completed research work No. 18-26.

Keywords: building structures, safety, cable trestle, emergency response, technical expertise, buildings and structures, metal structures, reinforcement project

The article discusses the main causes of natural gas leaks and ways to detect them. Data on the volume of natural gas leakage and the nature of damage were obtained at the experimental installation. The objects of experimental research are gas connections to devices, such as: bellows hose made of stainless steel, rubber hose and cap nut of gas connection with varying degrees of tightening. The course of conducting an experimental study of filling a room with natural gas, depending on the degree of damage to the gas supply and its nature, is described. The analysis of the results of the experiment to determine the dependence of the gas flow rate on the type of damage to the gas supply is carried out. The most dangerous types of leaks in the room are determined, graphs of the dependence of gas flow through various damages and methods of their prevention to prevent such situations are constructed.

Keywords: gas leak, gas appliances, leak detection, types of gas leaks, type of damage to the gas supply

The results of research permissible longitudinal axial and fiber tensions are given for various characteristics of gas distribution and gas consumption systems.

Keywords: polyethylene gas pipeline, longitudinal axial tension, longitudinal fiber tension, gas pipeline deformation, optimal gas pipeline bending radius

The article deals with the issues of assessing the effectiveness of the construction and operation of metal corrugated pipes. The characteristic features and difficulties of the operation of corrugated metal culverts in areas of permafrost distribution are revealed. The characteristics of the main defects of culverts are systematized. The features of thermophysical calculations of metal corrugated pipes on a frozen base are analyzed in detail. Recommendations are given on the application of the most effective technical solutions in the construction of corrugated metal culverts on permafrost soils.

Keywords: highway, culverts, metal corrugated pipes, thermal conductivity, permafrost soils

To assess the quality of the road surface, there are many systems that work on the basis of specific algorithms, including image segmentation methods. Time complexity and classification accuracy are two key indicators when evaluating the effectiveness of a particular algorithm. In this article, the following image segmentation methods are used as the analyzed methods: k-means clustering, Linear clustering, Adaptive thresholding, Global thresholding. Based on the methods described in the section "Methodology of experiments", the "Global thresholds" method has the best indicators of classification accuracy and time complexity (38.2% - classification accuracy; time complexity is linear (other methods have the same type of complexity, however, GT has much less absolute time indicators).

Keywords: comparison, method, segmentation, image, photo, road, surface, condition, accuracy, classification, time, complextion

Three-dimensional printing (3DP) in building industry has a number of important advantages, such as creation of various geometric forms without the need for molds, the ability to create complex elements, the possibility of automation, speed and a low amount of waste, the use of innovative materials, construction in layers of different materials, and more. So, 3DP is an effort to put digital manufacturing into practice, enabling a direct transition from building design / modeling (BIM) to 3DP. One of the important limitations in 3DP is the materials. Because printing is done in layers, it is important to take into account the hardening time of the material and its ability to stick to create a uniform structure. Another problem is the tolerance of the material to different types of solidification: melting, pressing. That's why there are methods for combining iron or polymer reinforcement. There are combined methods: 3D printed elements are used as prefab elements to make the building process more effective. This industry is one of the fastest growing manufacturing technology sectors covers all markets from aerospace and healthcare to construction and consumer products. This article provides some aspects of application in construction, materials and their compositions, as well as examples of the use of 3DP at buildings, structures, etc.

Keywords: 3D technologies in civil engineering and construction, materials for 3DP, 3D concrete printing, concrete polymer reinforcement, dispersive reinforcement concrete

The technology of organizing the construction of decentralized energy systems based on wind power plants is given. New design solutions for the structural elements of wind turbines and overhead lines (tower, collapsible ballast-type foundation, protective element) are proposed, taking into account the specifics of the technology of construction and installation works. Data are given on reducing the cost of construction production by optimizing the machines and mechanisms used.

Keywords: wind turbine structures, overhead lines, tower, collapsible ballast-type foundation, protective element, in-line method, decentralized system

Road surface quality assessment is one of the most popular tasks around the world. To solve it, there are a large number of systems that work using certain algorithms, including methods of morphological image processing. One of the key criteria for the effectiveness of an algorithm is its time complexity. The following approaches of morphological processing is considered in the article: Dilation, Erosion, Morphological Gradient, Morphological Smoothing. Photos of the road surface of various conditions were used as the material for the study. Based on the proposed methodology of the experiment, it turned out that each of the selected algorithms has a linear time complexity, but the "Dilation" and "Erosion" algorithms have lower absolute time indicators.

Keywords: comparison, efficiency, morphological technique, processing, image, photo, road, condition, time, complexity

The most significant advantage of composite structures compared to structures made of traditional materials is the ability to control the characteristics of the structure in order to obtain an optimal design. In the general case, the initial physical characteristics of the material of the composite structure are random variables. Consequently, the required quantities (stresses, strains, critical loads, etc.) are also random variables. The problem of statistical modeling of a composite structure is ultimately reduced to the problem of transforming random variables. To solve this problem, the Monte Carlo method is used. The object of study is a multi-walled plate under the action of compressive loads. The purpose of this work is to construct point estimates of the coefficients of both general and local stability for a multi-walled plate, as well as to test statistical hypotheses about the equality of the stability coefficients to their theoretical values. The initial parameters are the elastic moduli in the longitudinal and transverse directions, as well as the shear modulus of the construction material. The following were used as output values: sample mean, standard deviation, skewness and kurtosis coefficients. All calculations were carried out in the environment of the MAXIMA package. It is shown that the distribution of the overall stability coefficient practically does not differ from the normal distribution. The coefficient of local stability has a slight positive asymmetry and a steeper peak compared to the normal curve. The results obtained allow us to conclude that the spread of the elastic characteristics of the material does not significantly affect the coefficients of the general and local stability of the multi-walled plate.

Keywords: statistical modeling, statistical hypothesis, multiwall plate, stability, critical load, composite material

The experience of standardization of modular construction and factory-ready buildings of China, the USA, Canada, Great Britain, France, the Netherlands, Germany and others is considered. The analysis of the existing profile regulatory and technical documentation (RTD) in the Russian Federation. The analysis of domestic and foreign RTD showed that there is no unified approach to rationing of the considered subject area. At the present time it is necessary to update the Russian RTD in the field of modular construction. Based on the results of the analysis and synthesis of the world practice in the field of modular construction, recommendations and suggestions for working with terms and definitions, the variants of development of normative and technical documentation of the Russian Federation in the field of modular construction and themes of work for the development of modular construction regulation were developed.

Keywords: modular construction, quickly erected buildings, prefabricated buildings, technical documentation

Brief characteristics of mineral fillers used in the composition of building mortars are considered. The features of their application are also analyzed, some regularities are established in mixtures with polymer additives, which must be taken into account when selecting the compositions of dry mixtures.

Keywords: dry building mixes, building mortars, hydraulic mineral additives, inert filler, redispersible powdered polymer, adhesio

This article investigates the temperature distribution over the thickness of the elements when welding tee joints with fillet welds. The temperature was measured by thermocouples with corresponding readings recorded on an oscilloscope. At the same time 6 thermocouples were recorded, which made it possible to trace the entire process of temperature change (the process of heating and cooling) and to determine the maximum temperature at the points under study. The experimental results were compared with the calculated temperature values. Comparison of the experimental data with the calculation results showed quite satisfactory agreement what makes it possible to use the theory of heat propagation in welding by N.N. Rykalin to the design of temperature in tee joints when welding fillet welds.

Keywords: residual welding stresses, temperature distribution during welding, thermocouples, T-joint with fillet welds, temperature distribution through the thickness of the element, “small” thicknesses, “large” thicknesses

Modern cinema demonstration technologies have changed the perception of the auditorium space. Multi-channel digital stereo demonstration, the use of mobile platforms for seating created conditions for the design of small-capacity auditoriums with a round plan shape. Wall enclosing structures in this case have the shape of the inner surface of the cylinder. Finishing with acoustic plates on the frame is time-consuming and does not always allow you to repeat the shape of the fence. The design of acoustic decoration of cinema halls with a round or oval shape of the plan is rationally carried out with the use of acoustic foam "Flexacoustic" on the walls and Soundec ceiling panels (Soundec). The most effective combination, providing uniform sound absorption in frequencies, was obtained by using acoustic foam rubber "Flexacoustic" with a density of 30 kg/m3 and wood panels "Soundek" with a density of 450 kg/m3 with internal filling plates "Acoustic Fiber". The study of the use of domestic materials that are convenient for finishing works and recommendations for the choice of rational use, different in properties of acoustic building systems, allowed us to obtain results that will ensure the best conditions of audibility in the cinema hall.

Keywords: cinema, auditorium, room acoustics, sound-absorbing materials, sound absorption coefficient, average geometric frequency, soft acoustic plates

In this article, the calculation and evaluation of building structures of vertical steel tanks, which are subjected to various loads, is carried out.

Keywords: oil industry, petroleum products, accidents, vertical steel tanks, load

The article discusses the effect of adhesive additives on the performance properties of asphalt concrete. The authors give a comprehensive overview of the problem of durability of asphalt concrete layers, in particular in the autumn-spring period, emphasizing the importance of this issue for traffic safety. Then they discuss the role of adhesive additives in improving the performance of asphalt concrete by improving its physical and mechanical properties. The authors selected a number of adhesive additives, and also carried out the selection of asphalt concrete mixture according to the methodology of volumetric and functional design. The article contains a detailed description of the method for determining water resistance and adhesive properties. The authors also consider the effect of adhesive additives on the fatigue life of asphalt concrete. The text of the article provides a detailed description of the method for determining fatigue strength during repeated bending. In conclusion, the article emphasizes the importance of using adhesive additives to improve the performance and durability of asphalt concrete. The authors emphasize the importance of the study for extending the service life of asphalt concrete layers and increasing their repair time.

Keywords: bitumen, adhesive additive, low temperature property, water resistance, fatigue properties, composition selection, volumetric and functional design, durability, road, asphalt concrete, testing

The assumptions of mathematical models for calculating the crack resistance of reinforced concrete structures are considered. For each of them, an analysis was carried out to determine whether they correspond to reality throughout the entire life cycle of the structure: from the hardening of the concrete mix to destruction. Based on the results of the analysis, it was proposed to use only one single calculation at the level of standards to assess the crack resistance of structures - according to the crack opening width, acrc. So, for example, at a certain value of acrc, the structure will still remain airtight (the cracks will be non-through), and if this value is exceeded, it will not. At the same time, the calculations already available in the norms for limiting permeability and the safety of reinforcement will still remain in demand. At the junction of the theory of damage accumulation and nonlinear fracture mechanics, a compressed algorithm is proposed for possibly taking into account the influence of cracks at all scale levels of the concrete structure, the key for which is the normalization of the statistical parameters of the distribution of discontinuities by diameters, lengths, openings, depths, directions, distances between discontinuities, etc.

Keywords: reinforced concrete, crack resistance, cracking moment, crack width, plasticity coefficient, damageability, non-linear fracture mechanics

The study of statically indeterminate reinforced concrete structures at the present stage is possible with the help of software systems capable of taking into account the nonlinear work of the material, which allows us to fully assess the stress-strain state for a different redistribution of emerging forces provoked by corrosion damage to reinforcement and concrete. Numerical studies of 14 models with corrosion damage in the upper section of a two-span beam in the Ansys software package have been performed. Load-deflection graphs are presented depending on the percentage of corrosion damage. The dependences of the redistribution of tensile forces in the beam reinforcement with different percentages of corrosion damage are shown. It is established that with damages up to 10%, there is a sharp increase in the tensile forces in the span reinforcement of the beams. It is determined that with corrosion damage to the beam up to 70%, the forces in the supporting reinforcement increase to 10%.

Keywords: reinforced concrete beam, redistribution of forces, plastic hinge, corrosion of reinforced concrete, numerical calculation, bearing capacity

Currently, the energy efficiency of buildings is one of the most pressing economic and environmental problems. Reducing energy costs not only minimizes building maintenance costs, but also reduces the negative impact on the environment. This article deals with the problem of increasing the energy efficiency of the enclosing structures of polyclinic buildings and proposes a method for measuring the economic efficiency of the proposed enclosing structures of municipal polyclinics in Moscow. The implementation of an energy-efficient project for the reconstruction of polyclinic buildings requires an integrated approach, which includes the selection of optimal materials and structures, a thorough analysis and calculation of energy efficiency by measuring the savings in heat loss after the reconstruction of buildings. The implementation of this approach will reduce heat loss and increase the comfort of staying inside the buildings.

Keywords: energy efficiency, heat losses, reconstruction, enclosing structures, medical and healthcare institutions

In order to form comprehensive decisions on the organization of traffic, realizing long-term strategic directions for ensuring the efficiency of traffic organization and improving activities in the field of traffic organization, it is necessary to use the means of mathematical modeling of traffic flows. The main indicators of the effectiveness of traffic management are improving road safety, reducing the number of transport delays and increasing the capacity of the road network, as well as reducing the negative impact on the environment of vehicles.

Keywords: intensity, traffic management, traffic flow, traffic light regulation, traffic accident, accident focus, transport hub, accident rate, traffic safety, traffic capacity

The value of the efficiency of domestic gas boilers of the brand Baxi ECO-4S 24 with various schemes of air supply and smoke removal is considered. The difference in the calculated efficiency values and the passport values is analyzed.

Keywords: efficiency, flue gas discharge, household gas boiler, thermal balance, energy efficiency

The article presents the results of a comparative analysis of practical calculations of driven and bored piles, which have similar geometric parameters and common geological conditions of construction sites. Taking into account the peculiarities of the use of these piles and the available experimental data, the paper analyzes the calculated values of their bearing capacity and gives an engineering assessment of the results of the calculation. The quantitative difference between the determined parameters of the bearing capacity of piles - friction along the lateral surface and frontal resistance, is clearly shown in the constructed diagrams. So, when using the standard values of the coefficients to determine the bearing capacity of piles, we have a significant excess of this parameter for driven piles. The need to use more gentle methods of driving piles to the design depth leads to the possibility of using the technology of arranging bored piles, which have a lower bearing capacity with the same parameters as driven piles. This feature should be taken into account in engineering calculations when selecting the optimal dimensions of bored piles.

Keywords: driven piles, bored piles, geological conditions, engineering calculations, bearing capacity

Determination of pile bearing capacity located in collapsible soils. This work simulates the tests in the Plaxis 2D software system, and also determines the bearing capacity in accordance with paragraph 9.9 of SP 24.13330.2021 Pile foundations. Modeling of three capacity tests lead to recieve different results according to chosen method of tne results evaluation. Based on the results of the article the imperfection of the current Russian regulatory document in the field of field testing of piles was revealed. However comparing of the test results was made with analytical calculation of pile bearing capacity.

Keywords: collapsible soils, pile bearing capacity, pile tests, finite element modeling, Plaxis