ANALYSIS OF EXISTING SOLUTIONS FOR IMPROVING THE MEASURING AND COMPUTING COMPLEXES OF HEAT SUPPLY NETWORKS

In the presented article, the team of authors considers the existing methods and the main modern technical solutions that are currently implemented in different countries in the diagnosis of heat supply networks. There is a selection of the main directions in the development and design of heat supply networks, which have already been implemented or supported by scientific teams from different countries. Various methods and technical features of diagnostics are reviewed, strengths and weaknesses of the presented solutions are highlighted. The reviewed works were subjected to detailed analysis, which revealed the presence of a high interest of the scientific and industrial community in the integration and improvement of existing digital technologies in the development of heat supply systems, which would be closely related to forecasting and modeling processes in this industry. The team of authors highlights the main vectors for the development of this sector, citing an example of a significant increase in the degree of digitalization of final products, which makes it possible to use data analytics to obtain effective technical solutions regarding heat supply networks. Separately, the positive experience of different countries in this industry is noted when using neural networks not only in the design of heat supply networks, but also as a target industry as a whole. Assumptions are put forward about the need for a detailed analysis of the existing foreign and domestic experience, as well as scientific developments in this area, in order to determine the most suitable technical solutions on the territory of the Russian Federation, which will take into account the climatic characteristics of the country and be based on methods of large data analysis, computer vision and simulation. modeling.

CHANGE IN STRENGTH PARAMETERS OF DISPERSED SOILS AFTER HIGH-FREQUENCY VIBRATION

The use of the technology of high-frequency sheet piles driving or extraction in conditions of weak, structurally unstable soils inevitably leads to a change in the structure of the soil. This is especially true for buildings which fall into the zone of influence. Often, foundation for historical buildings is water-saturated sands, spread by fluid and fluid-plastic clay soils. In the process of external dynamic action, the soil foundation is been destructing, so their strength and deformation parameters are reduced. In this case, the result of vibration effects on a dispersed water-saturated sample can be both compaction for sandy soil and decompaction of clay soils. These changes lead to additional deformations of buildings and structures of the surrounding area. Therefore, the issue of assessing the limits of applicability of vibration technology in certain conditions is relevant. The object of the study is the changes in the properties of clay soils of various consistencies after exposure to vibration. The results of laboratory studies to determine the strength parameters of dispersed soils after high-frequency vibration are presented. The results of field measurements by CPT "before", "after" vibration immersion and vibration extraction of sheet piles are considered. Comparison of the results of field and laboratory studies is carried out to identify patterns of change in the strength characteristics of weak soils under the influence of vibration loads. A tendency towards a decrease in the strength parameters of dispersed soils is shown. Currently, due to the insufficient number of laboratory and field studies to study the effect of high-frequency vibration on the change in the strength parameters of weak water-saturated clay soils, it is not possible to identify a clear dependence of the change in parameters on the time and frequency of vibration.

CALCULATION OF THE BEARING CAPACITY OF A TWO-SLOT STRIP FOUNDATION

The results of computer modeling of the process of formation and development of areas of plastic deformations in the connected base of a double-slit ribbon foundation are presented. All calculations are performed using computer programs developed with the participation of the author. These programs allow you to take into account all the variety of physical and mechanical properties of the foundation soil (volume weight, internal friction angle, specific adhesion, lateral pressure coefficient and deformation modulus) and the foundation material (elastic modulus and Poisson's ratio). In the calculations, it is assumed that the value of the lateral pressure coefficient of the soil is 0.75, as is typical for cohesive clay soils, and the same value for the foundation material is assumed to be 0.43 (converted through the Poisson's ratio). Based on the results of calculations, it was possible to determine the features of the stress state of the base of the double-slit foundation and the process of development of plastic areas in the core of the foundation. First of all, the part of the bearing capacity of the base of the double-slit foundation that contacts its side surface is realized, and the inclusion of the side surface of the slit foundation in the work occurs from the bottom up. Then the part of the base that is located directly under the soles of the walls in the ground (cracks) is included in the work. It is established that the smaller the distance between the slits, the greater the bearing capacity of the base and the greater its part falls on the side surface. The bearing capacity of the base of a double-slit foundation is directly proportional to the depth of its foundation (the height of the cracks). The part of the load-bearing capacity realized on the side surface of the foundation can reach 60 % or more of its full value. An engineering method for calculating the load-bearing capacity of the base of a double-slit foundation, including simple formulas and graphs, is proposed. The method is formalized in a calculator program. The verification calculations showed a high degree of accuracy in approximating the results of the numerical experiment.

RESULTS OF VIBRATION MONITORING OF VIBRO-DRIVING AND VIBRO-EXTRACTION OF SHEET PILES

The geology of St. Petersburg is represented with a heavy layer of weak structurally unstable soils. Using of vibro-extraction and vibro-driving of sheet piles in such conditions requires a particularly responsible approach in order to predict the emerging dynamic effects and the zones of their influence on the surrounding buildings and structures. Therefore, the task of looking for possible patterns describing these processes is highly relevant. For this purpose, the authors have updated the map of engineering-geological zoning according to Zavarzin with use of more than 50 reports of engineering-geological surveys. On this map the sensitive to the high-frequency vibrations soil layers are identified. Also, more than 70 reports on vibration monitoring of vibration driving and vibration extraction of sheet piles in St. Petersburg have been analyzed. The influence on the value of vibration acceleration of the following factors has been investigated: the geological features of the site, the distance to the source of vibrations, the characteristics of the vibrating hammer (operating frequency, driving force) and sheet pile (length, cross section), the location of measurements (on the ground or on a structural element of the building). The result of the work is the diagrams that clearly show the presence or absence of a relationship between the studied parameters. The absence of dependencies for some of the investigated parameters may be caused by the factors which influence cannot be predicted. These factors are the occurrence of large friction forces in the joints of sheet piles; the presence of lenses of dense soils or boulders during sheet piles driving; violations of the technological process. The zone of the influence of high-frequency dynamic impact was identified as 25 meters, which is in good agreement with the results of in-situ monitoring.

MODELLING AND MONITORING OF STRUCTURAL SAFETY OF UNIQUE UNDERGROUND STRUCTURES OF THE SEWAGE SYSTEM OF LARGE CITIES IN DIFFICULT GROUND CONDITIONS

Anthropogenic and dynamic impacts on facilities of underground urban infrastructure increase at intensive development of megacities. The unique long-operating underground structures of sewage system require special protection against anthropogenic influence as their wear degree in difficult soil conditions reaches 70 % and more. Therefore, providing structural (mechanical) safety of underground structures of excessive level of danger and responsibility defines sustainable operation and future development of geotechnical infrastructure of the megacity in general. Long-term studying dynamics of changes of technical state of underground sewage structures of the megacity, long operating (for more than 70 years) in soft soils, allowed establishing regularities of influence of intensive anthropogenic and dynamic impacts on this process. For the first time, based on developed continuous models of defective structures potentially dangerous sections have been identified, they are subjected to manifestation of critical failures; ways of their correction are presented. Numerical simulation has defined borders of defectless joint operation of the system “target area - geomassif - underground structure". Scientific substantiation of boundaries of areas with potentially dangerous sections of underground sewage facilities with account of external anthropogenic and dynamic impacts constitutes the basis for elaborating regulations on safe development of geotechnical infrastructure of the historical area of St. Petersburg. The proposed methods of monitoring and protection of geotechnical infrastructure have been successfully used for many years by St. Petersburg Vodokanal in areas of influence of anthropogenic factors and objects under construction on underground structures, they ensure an optimal combination of sustainable operation and development of geotechnical infrastructures of megacities.

HEAT-RESISTANT CONCRETE BASED ON ORTHOPHOSPHORIC ACID, WASTE OF NON-FERROUS METALLURGY AND CHEMICAL INDUSTRY

Currently, as numerous studies show, raw natural resources are running out, so it is necessary to involve in the production turnover of industrial waste for the manufacture of heat-resistant concrete. At the same time, the costs of geological exploration, construction and operation of quarries are excluded, and significant land plots are freed from the impact of negative anthropogenic factors. Multi-tonnage waste of non-ferrous metallurgy-ferrite-calcium slag containing 50-51 % Fe2O3, was used as an iron-containing filler for the production of heat-resistant concretes. Ferrite-calcium slag is a man-made raw material (production waste) of processing copper-zinc concentrates, obtained by slow cooling of the material to complete scattering, light yellow in color and resembling fine sand. The trivalent iron oxide Fe2O3 contained in the slag reacts very slowly with orthophosphoric acid H3PO4 at normal temperature; therefore, it is necessary to heat the mixture to 70 °C, since its own heat is not released by the reaction. A, the ferrous iron oxide FeO contained in the slag, as well as Fe(OH)3 hydroxide, on the contrary, reacts with the acid vigorously, releasing a significant amount of heat, so the binder dough begins to set after 2 minutes at a temperature of 20 °C due to significant heat release. Chemical industry waste - the spent IM-2201 catalyst was used as an aluminum-containing raw material and is a fine powder with a specific surface area of up to 8000 cm2/g and a fire resistance of up to 2000 oС. Studies have shown that due to the use of orthophosphoric acid as a binder, it is possible to dispose of up to 80-90 % of non-ferrous metallurgy and chemical industry waste and at the same time obtain heat-resistant concretes with high physical and mechanical properties.

IMPORT SUBSTITUTION IN THE INDUSTRY OF WATER SUPPLY AND SANITATION

Import substitution in the industry of water supply and sanitation (WSS) in the context of the current economic crisis is a rather attractive operation. The problem of import substitution in the water supply and sanitation industry is complex being characterized by features such as production conditions, the availability of scientific and technical developments, the intensity of relations with foreign colleagues. Many WSS sector participants focus on implementing measures to reduce their dependence on foreign suppliers and shifting to products of domestic manufacturers within the framework of import substitution. The overall goal of this paper is to assess the feasibility of import substitution in the sector of water supply and sanitation in Russia. In addition, the article offers a choice of equipment in the field of water treatment, which can be produced in Russia in order to create products that are competitive on the world market. This article provides a review and analysis of the nomenclature of the main and auxiliary equipment for the water supply sector. The article offers an overview of patents for useful models in the field of water treatment which are feasible to produce in the domestic industrial market, however, they are currently imported from abroad. The review investigates the extent of import substitution demanded by the industry of water supply and sanitation in Russia. It also describes types of water treatment equipment to be produced in Russia. The structure of the paper is as follows: - the history of the development of water supply and sanitation industry; - the analysis of the current status of water supply and sanitation industry of Russia and review of basic technological equipment for natural water treatment plants and for wastewater treatment; - the review of utility model patents in the field of water treatment; - the conclusion.

THE ANALYTICAL DETERMINATION OF THE PARAMETERS OF THE WELL WHILE ELIMINATING UNEQUAL SETTLEMENT OF FOUNDATIONS METHOD OF DRILLING-OUT OF THE SOIL

Existing approaches which allow to reduce the settlement unevenness of buildings and structures have their own advantages and disadvantages. One of the promising methods for reducing shallow foundations the settlement unevenness, which are based on soft dust and clay soil, is the building or its part lowering. The effect is achieved by drilling vertical wellbores in the immediate proximity to the existing foundation from the side of the least settlement. At different times, domestic and foreign scientists were engaged in to the methods of horizontal and inclined drilling of wellbores, an important issue, when applying this technology, is the determination of drilling parameters, the influence of soil characteristics and the stress state of the soil around the well, on the roll reduction process. The article considers the influence of the soil strength characteristics on the stress state of the soil which are surrounding the wellbore, and the effect of the drilled wellbore radius on the formation of the critical state regions. The analytical solution is based on the use of the well-known relationship for determining the stress state around the well during pressiometric tests. From this ratio, tangential and radial stresses are determined, which are then checked according to the condition of the law of strength, thereby forming a picture of the stress state around the well. According to the presented methodology, the stress state of the soil around the wells was calculated, which allows calculating the zones of soil destruction and thereby determining the parameters of the wells and the geometry of their location depending on the goals, when regulating the sediment of slab foundations.

THE EFFECT GRAIN-SIZE COMPOSITION ON THERMAL CONDUCTIVITY OF SANDY SOILS

Today the issue of energy saving is acute. The main sources of energy are radiant energy of the Sun, wind energy, energy of moving water. Therefore, the issue of solving alternative energy sources is relevant. The article aims to solve the problem by using low-potential heat of the soil mass by means of energy-efficient building constructions - foundations. It is necessary to know the thermal characteristics of soils for this. At the moment, methods for determining the thermophysical properties of inert materials with subsequent practical application in the field of construction have been widely studied, but no one of these methods takes into account the grain-size composition. Thus, the study of the connection between the thermal conductivity and the grain-size composition of the soil is important. The aim of the work is to Estimation of thermal conductivity of sandy soils based on grain-size composition. This article presents an analysis of the dependence of the thermal conductivity of the sandy soil of its grain-size composition. The matrix of experiment planning is made; the methodology and technological sequence of the experiment were tested. Statistical processing of the obtained experimental data was carried out. Based on a series of test experiments, it was concluded that there are two factors competing in its thermal conductivity: an increase in λ due to an increase in the degree of pore filling and a decrease in total heat conductivity due to a decrease in the degree of pore filling. These results suggest that grain-size composition has an impact on the thermal conductivity of the sandy soil. During the experiment, the dependence of the thermal conductivity of sandy soils on their grain-size composition was experimentally established.

DETERMINATION OF DEFORMABILITY PARAMETERS OF CONCRETE SAMPLES BY THE FORMULAS OF FRACTURE MECHANICS

To determine the deformability parameters of concrete samples by the formulas of fracture mechanics, equilibrium tests were carried out at the stage of local deformation of the sample, which showed the correspondence of the change in external forces to the internal forces of the material resistance with the corresponding static development of the main crack. For the same purpose, the samples are tested for bending with an initial notch and the “load-deflection” diagram is recorded. In this work, we presented a test scheme for a specimen with a notch (crack) and constructed a diagram of the deformation of a specimen under bending “load-deflection”. Based on it, it is possible to predict the destruction of the material, that is, to determine the value of the load at which the limit value of deflection or the displacement of the outer edges of the notch (opening the throat of the crack on the lower surface of the specimen) can be taken as the moment of loss of the resource of the material. Also, we examined the deformation of a concrete sample during three-point bending and presented a diagram of the deformation of a concrete sample within the plastic zone. Dependencies were derived for determining the ultimate relative strains under tension and bending. Based on the results obtained, the state diagrams of the stretched concrete and the deformation scheme of the normal section of the concrete sample were constructed. As a result, the conclusion and convergence of the results.