Vol 14, No 3 (2023)

Modeling of the possible negative impact of mudflows in the monitoring of mudflow basins of the river Mzymta
Bandurin M.A., Volosukhin V.A., Prikhodko I.A., Rudenko A.A.

Abstract

The article considers the identification of potential sources of formation of water and mudflows in the area of the Olympic objects of the southern slope of the Psekhako ridge and the catchment areas of the 1st, 2nd and 3rd Galion rivers (the catchment area of the Mzymta river). The collection and study of natural, climatic and morphological characteristics mudflow basins and the study of the possibility of their negative impact on the operated Olympic facilities, the creation of a database of mudflow basins. Implementation of the results of studies of the natural-climatic and morphological characteristics of the mudflow basin of the river. Mzymta is assumed in the justification of anti-mudflow measures to protect the infrastructure of operated Olympic facilities from the negative impact of water and mudflows. To ensure the reliability of the functioning of these foundations and foundations of structures. It is important to take into account the possibility of a negative impact on them of water and mudflows that form in the conditions of mountainous terrain and natural and climatic features of this region, as well as due to the extremely insufficient knowledge of the current state of development in these territories. mudflow processes and the possibility of their activation as a result of the impact on the natural landscapes of mudflow basins during the operation of the foundations and foundations of Olympic facilities and their infrastructure (access and technological roads, power lines, ski slopes, chairlifts, various sites, etc.). Taking into account the impact of the consequences of a large-scale technogenic impact on the natural landscape, in the territory of operation of the Olympic facilities along the southern slope of the Psekhako ridge, the materials of the survey confirm the conclusions about the increased mudflow hazard of the watercourses of the river. Rudnichny, r. Sumasshedshiy, r. Kamburovsky. The main reason for the descent of these mudflows is the technogenic impact on the upstream natural landscapes, including the discharge of liquefied soil dumps from steep slopes, the concentration of surface runoff into concentrated eroded, cuts, etc. Simulation modeling of the stability of the river slopes was performed. Tobias, the most dangerous combinations of impacts under static and seismic conditions, to predict the formation of mudflows.
Construction and Geotechnics. 2023;14(3):5-15
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Selection of equipment for experimental studies of the stress-strain state of reinforced soil bases and pavement structures
Kleveko V.I., Teterin E.I.

Abstract

Reinforced soil structures are often used in the practice of transport and industrial construction. The existing methods for calculating such structures have a number of significant drawbacks and do not always allow to accurately determine the design parameters, especially for settlement and tensile stresses in the reinforcing layers. To improve the methods for calculating reinforced soil structures, it is necessary to conduct full-scale experiments to determine their stress-strain state. Field experiments to assess the stress-strain state of reinforced soil structures are a complex technical problem. Most often, in these full-scale experiments, round stamps of various diameters are used. In the course of research, it is necessary to measure normal stresses and vertical displacements in the core of the reinforced soil base and tensile stresses in the reinforcing layers. To improve the accuracy of measurements and reduce the distortions that sensors introduce into the stress-strain state of reinforced soil structures, their careful selection is necessary for a number of parameters. The paper provides recommendations on the selection of pressure sensors for measuring vertical normal stresses in the soil mass. The diameter of the pressure sensors should not exceed 28-80 mm, depending on the diameter of the round die used for testing, and the recommended thickness of the pressure sensors should not exceed 2.8-8.0 mm. After the selection of pressure sensors, it is necessary to determine the measuring strain gauge system. The main criteria for selecting a measuring strain gauge system are the number of active strain gauges in each pressure sensor, the total number of measurement channels, and the electrical resistance of strain gauges. To measure tensile stresses in the reinforcing layers, you can use miniature strain gauge sensors using bridge or half-bridge connection schemes for active strain gauges.
Construction and Geotechnics. 2023;14(3):16-23
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The effectiveness of using the bearing capacity of piles in the formation of the pile field of the slab pile foundation of a 21-storey apartment building
Skibin G.M., Derekhovskii V.M.

Abstract

This article is aimed at studying methods for optimizing the pile field in order to ensure the greatest use of the bearing capacity of piles, adopted in the project, considering the most unfavorable design combinations of forces. The object of the study is a multi-storey apartment building on a slab-pile foundation with a regular grid of piles, which clearly shows the imperfection of the calculation methods, due to the incomplete use of the bearing capacity of a significant number of piles, but the methods described in the article are also applicable to other buildings on slab-pile foundations, especially the difference between the original scheme and the optimized scheme will be clearly visible on the example with longer piles in less bearing soils, spread over the entire depth of the foundation. The purpose of this study is to study methods for optimizing a pile field, to study the methodology for using these methods on a specific example and compare them in terms of the parameters of using the bearing capacity of piles: the absolute and relative value of the minimum load on the pile, the absolute and relative value of the maximum load on the pile, the absolute and relative value average load per pile, as well as their comparison of economic efficiency. In the course of the article, numerical modeling was used, using the finite element method and analysis of the results of multivariate calculation. The result of this article is the application of pile field optimization methods to the multi-storey building on a slab-pile foundation, the evaluation of each of the methods and their comparison according to these indicators, as well as an understanding of the further development of this topic.
Construction and Geotechnics. 2023;14(3):24-36
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Experimental studies of the stability of wave-damping slopes to protect bridge supports from wave action
Tlyavlina G.V.

Abstract

This article presents the results of experimental studies of the stability of wave-damping slopes to protect bridge supports from wave action. The object of the study is the construction of protective wave-damping slopes constructed to protect the supports of bridges designed and operated under wave action conditions (such as the bridge to Russian Island in Vladivostok, etc.) on the shores of the seas. The purpose of the work is to select the optimal design solutions for protective slopes that ensure reliable and safe operation of the bridge crossing during sea storms of rare frequency. The research was carried out by the method of physical modeling in a wave pool. Various variants of structural solutions of protective slopes are considered: from a stone outline and from gabions, as well as combined structures. According to the results of research on a physical model in the wave basin, the structures of the protective slopes of bridge supports that are most resistant to the effects of sea storm waves of rare frequency have been obtained. The results of the research are intended to select optimal design solutions for protecting bridge supports from wave action and can also be used to protect other transport structures, for example, the roadbed of railways designed on sea coasts. These results were used by the author in the development of the regulatory framework for the design and monitoring of engineering structures for the protection of transport structures from wave action.
Construction and Geotechnics. 2023;14(3):37-50
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Evaluation of peel resistance of paint coatings depending on the roughness of the cement substrate
Ariskin M.V., Svetalkina M.A., Loganina V.I.

Abstract

The object of the study is paint and varnish coatings of cement concrete. The goal is to evaluate the stress-strain state of coatings under the action of temperature depending on the geometry of the substrate roughness relief. The results of calculating the distribution of stresses over the cross section of the coatings and the possibility of their peeling are presented. The SCAD Office software module was used for the calculation. Heavy concrete was considered as the substrate. Polyvinyl acetate cement PVAC paint was used as a paint composition. The calculations were carried out for the conditions of Moscow. A comparison is made of the stresses in the coating on a smooth and rough surface. I has been found that an increase in the relief angle of the substrate surface roughness does not cause a significant change in the magnitude of stresses. The stress concentration in the zone of contact between the coating and the rough surface of the cement substrate has been established. A diagram of the distribution of stresses in the PVAC coating is presented. It was revealed that at some distance from the zone of the microdepression of the substrate surface relief, an increase in stresses is observed, which, depending on the angle of inclination of the relief, are s х = (1.007-1.021) MPa. At the peak of the relief, the stress values in the contact zone are less and amount to 0.403-0.441 MPa. The influence of the substrate roughness has practically no effect on the values of normal stresses on the coating surface, which are 0.835-1.001 MPa. The probability of peeling off the coating is estimated. The possibility of peeling of the coating has been established, tk. stress values are less than the adhesion strength, which is 0.9-1.1 MPa. It is recommended that in order to increase the resistance of coatings to peeling, strive to create a uniformly distributed roughness of the substrate surface.
Construction and Geotechnics. 2023;14(3):51-58
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Evaluation of the effectiveness of the use of indicator methods in determining the carbonization of concrete
Goglev I.N., Loginova S.A.

Abstract

Currently, one of the most important problems is the impact of aggressive environments on reinforced concrete structures, as a result of which the process of their destruction is triggered. One of the reasons for the failure of reinforced concrete structures is the process of carbonization of concrete. In practice, in order to timely eliminate and prevent the problem of carbonization of concrete, an indicator method for determining damaged zones is used. However, the traditional phenolphthalein test method does not allow to determine with high accuracy the boundary zones of concrete that are most vulnerable to carbonization. The article discusses the possibility of improving the phenolphthalein test method by using additional solutions of acid-base indicators alizarin and neutral red. The results of experiments on measuring the surface neutralized layer of concrete with alcohol solutions of acid-base indicators alizarin and neutral red on concrete samples of various ages and sizes are presented. The results of a comparative analysis of the traditional and improved methods for determining the carbonization of concrete are presented. The method proposed by the authors is distinguished by greater accuracy of the results obtained. The solution of neutral red expands the boundaries of the application of the phenolphthalein test method for determining the carbonization zones of concrete at 6 < pH < 10.5. The use of alizarin in addition to the phenolphthalein solution is difficult because the indicator solution is too dull in color, resulting in the definition of zones of highly alkaline concrete not being accurate enough. Due to the fact that the phenolphthalein test method has limitations in its use by examiners at the field stage, it is advisable to continue the search for indicators that can supplement or fully replace phenolphthalein for these purposes.
Construction and Geotechnics. 2023;14(3):59-69
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Obtaining the empirical calibration dependence for express assessment of the quality of the performance of ground structures
Sazonova S.A., Tatiannikov D.A., Ponomaryov A.B.

Abstract

In this study, the authors consider sand pads, namely the production process and quality control. The main problem of using the compacting factor as a criterion for assessing the quality of sand pads is the impossibility of calculating future deformations of foundations, as well as the duration of laboratory studies to determine it. Thus, the development of a technological solution for the use of express methods for controlling the compaction of soil structures, which are based on empirical data and can reduce the economic costs of construction, is an urgent task. The direct object of the study is the sand pad under the production facility. In the process of installing a sand pad, layer-by-layer control of the degree of compaction was carried out according to the compacting factor with the determination of the maximum density according to the method of GOST 22733-2016, and the modulus of soil deformation according to selected soil samples for compression tests. For each layer, the compaction coefficient was determined at 5 points, the deformation modulus at 3 points. Additionally, tests were carried out using a dynamic density meter. The main result of the study is the construction of a calibration dependence of the constrained modulus on the dynamic modulus of elasticity of the soil based on the results of statistical processing. Based on the test results, it was found that the experimental data are equally accurate, the resulting model is adequate. The difference between the experimental data and the calibration dependence does not exceed 18 %, which is a good convergence for empirical methods. The obtained experimental dependence allows, with a sufficient degree of accuracy, to quickly control the quality of the sand pad.
Construction and Geotechnics. 2023;14(3):70-79
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Computer modeling of the interaction of the building underground part with the soil foundation during the karst cavity formation on the example of the administrative and business center construction
Ter-Martirosyan A.Z., Cherkesov R.H., Isaev I.O., Filaretov N.A., Vanina Y.V.

Abstract

In restrained urban conditions of Moscow, the accomplishment of complex urban construction projects is complicated by the choice of construction sites, as well as by lack of methods for computer modeling of the interaction of high-rise and unique buildings and structures with the probable formation of karst cavities in the current regulatory documents. The overall profitability of the project is under the great impact of it, therefore a reliable accounting of karts-suffusion processes is a priority issue in designing buildings and structures, especially if it concerns the unique and high-rise ones. The authors analyze the results of the calculations of the forecast assessment of the impact of a karst cavity probable formation on the subsurface parts of building of the administrative and business center construction in flat and spatial formulation. In spatial formulation different positions of the potential karst cavities are considered; their locations were chosen according to standard procedures and were guided by the results of geological and geophysical research. It has been reviewed the formation of arch over a karst cavity in a 2D and 3D formulation in the condition of different location of the karst cavities in plan and by depth of occurrence. It has been made methodological recommendations for determining the predicted bore of the karst cavity, for taking into account the frame stiffness of the aboveground part of the building, for defining the principles of a karst cavity modeling, as well as for the choice of assessment criteria of stability of cover mass above the potential cavity. The discovered differences in the results of 2D and 3D settings permit to make a conclusion that solving the problem in a flat formulation contributes to the overestimation of karst processes danger and, therefore, to the excess in anti-karst measures included in the project.
Construction and Geotechnics. 2023;14(3):80-91
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Computer modeling of the limit state of a slab foundation with regard to the rigidity of the above-foundation structure
Bartolomey L.A., Bogomolova O.A., Geydt V.D., Geydt A.V.

Abstract

The task of this research is to determine the values of the generalized strength parameters of the foundation soil and , at which the depth D Z of the development of Coulomb areas of plastic deformation under the edges of the foundation of finite rigidity thickness Н , loaded with a uniformly distributed load of variable intensity q and foundation of the same thickness, bearing a rigid above-foundation structure of variable height H * will correspond to the closure of plastic area under the base of the foundation what is complied with the ultimate state of the foundation (according to Prandtl). To carry out computer modeling a list of variables of design parameters that influence the process of formation and development of plastic areas under the sole of the foundation, and the intervals of their change, has been established. As a result of the calculations and processing of the data obtained it was found that the numerical values of and differ significantly from each other: equations of approximating curves of dependencies of the form have different forms correspondingly and are described by the different approximating expressions. If it is given the values of the generalized strength parameters of the foundation soil and , which the soil mass should have after its fixing, then using the graphs shown in Fig. 6-10 and the table it will be possible to conclude whether the limit state of the fixed soil base will be achieved under given loads. In other words, focusing on the numerical values of and , it is possible to determine the values , which must be obtained in the process of fixing the soil base so that the specified external load does not exceed the maximum permissible value.
Construction and Geotechnics. 2023;14(3):92-106
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Cementation of soils by wristband-pipe injection technology in conditions of thawing perpetually frozen soils
Pronozin Y.A., Naumkina Y.V., Epifantseva L.R., Gress Y.D.

Abstract

In the conditions of global warming of the climate in the territories of permafrost distribution it takes place the processes of increasing the temperature of perpetually frozen soils and increasing the depth of their thawing. These factors lead to a decrease in the structural safety of the buildings and constructions. Measures to return soils to the frozen state are not always feasible and effective. In such conditions the solution to the problem of decreasing the pile foundation bearing capacity can be the ground strengthening by the cementation using the wristband-pipe injection technology. In the article it is presented the experience of assessing the current technical condition and designing of bases and foundations strengthening of a three-storey residential building in Yamal-Nenets Autonomous District, village Muzhi. The object was given a limited-operational category of the technical condition due to the deficit of the pile foundation bearing capacity. To bring the constructions of the object to the working condition the project of pile foundation strengthening with the cementation by wristband-pipe injection technology was developed. While injecting the soil foundation with the hydraulic fracturing the additional (induced) tension state appears, and it changes the deformation and strength properties of soils, voids ratio, index of liquidity and modulus of deformation. Reinforced joints, soil compaction and stabilization appear due to the injection. While making the hydraulic test and fracturing in the soil body its stress and strain state is changing, foundation piles are stressed with the additional lateral pressure. Besides the soil is strengthening under the pile toe bulb. Analytical calculations are given for increasing the bearing capacity of a pile during cementation of soils due to the increase of horizontal stresses and the work of compacted foundation soil on the lateral surface and under the lower end of the pile.
Construction and Geotechnics. 2023;14(3):128-143
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