## Vol 14, No 2 (2023)

**Year:**2023**Articles:**11**URL:**https://ered.pstu.ru/index.php/CG/issue/view/381**DOI:**https://doi.org/10.15593/cg.v14i2

Analysis of the stress state at the contours of underground horizontal workings of elliptical cross-section shape subjected to all-round uniform pressure

#### Abstract

The results of the research to determine the stress state on the contours of underground horizontal excavations, the cross-section of which has the form of an ellipse of any size and shape are presented. When changing the intensity of tensile uniform pressure applied to the points of elliptical shape cross-section excavation contours, the given values of excavation depths, ellipse parameters and rock side spreading coefficient values, the areas of the contours with tensile and compressive stresses are identified. If the depths of workings of the considered form of cross-section change, the areas where tensile and compressive stresses act at given values of the intensity of tensile uniform pressure applied to the points of working's contours, ellipse parameters and values of the coefficient of rock lateral spreading are highlighted. The graphical images of the normal tangential stresses, acting on the contours of the considered workings are given. The ranges of intensity of the tensile uniform pressure, at which, depending on the depth of excavation, values of ellipse parameters and the coefficient of rock lateral spread, tensile and (or) compressive stresses act in the points of excavation contours have been determined. The given relations and results can be applied to calculate the values of the permissible values of all-round uniform pressure in the points of the workings contours and to determine the permissible depths of their embedding. As a criterion for determining the values of these values, the condition of absente on the contours of excavations of points in which the normal tangential stresses exceed the limits of tensile and compression strength of the rock can be accepted.

**Construction and Geotechnics**. 2023;14(2):5-21

Pile field numerical analysis at the stage of dynamic impacts

#### Abstract

The authors propose a combined approach for definition of the shear rigidity of the multilayered soil which is cut through by a pile. The static solution for the vertical direction is presented in the view of an axisymmetric problem. As to the horizontal direction, the solution is presented in view of a beam on elastic subsoil with genetically non-linear transition to equivalent horizontal dynamic rigidity of the wide pile field. At the stage of formation of the stress-strain state of the system under the main combination of static loads еhe axisymmetric solution provides visual clarity in the analysis of the stress-strain state of the pile and near-pile soil in comparison with the approved analytical methods. The horizontal rigidity is considered as for a discrete single bent pile in the medium of an elastic layered half-space. These methods of numerical modeling of deformations of a single pile make it possible to expand the algorithm of analytical calculation of a large pile field, which in turn is modified by the authors by excluding deformations of the pile body due to its natural consideration in the finite element formulation, as well as by the parameter of the limiting radius of the influence of a single pile on the settlement of neighboring piles. In this publication, the authors describe a methodological approach to constructing a model of a large-size pile field at the second stage of short-term or special dynamic impacts. A transition to the integral rigidity of pile groups is proposed, taking into account the spatial dynamic model of a large-size pile foundation. The numerical problems of modeling a spatial soil array, a wave method for determining the discreteness of the model, methods for replacing the underlying half-space with a contact model are considered.

**Construction and Geotechnics**. 2023;14(2):22-36

Features of stabilization of soft soils at the base of emergency deformed buildings using finely powdered injection materials in low pressure mode

#### Abstract

At present, the strengthening of the soil base is often performed by high-pressure injection - injection of a solution under pressure that exceeds the structural strength of the soil (hydraulic fracturing mode). High-pressure injection makes it possible to successfully solve various geotechnical problems, but it has a number of disadvantages, first of all, the uncertainty of the shape and size of injection bodies created in the soil mass, as well as the impossibility of predicting the final deformation and strength characteristics necessary for design. It should be noted that directly from the production of injection works in the uncontrolled hydraulic fracturing mode, unpredictable technological deformations (rise followed by uneven settlement) of the Objects are observed, the base of which is stabilized, as a result of which crack formation processes in above-ground structures and fragmentary destruction of load-bearing elements develop. The article considers the possibility of solving the problem of predictable increase in the mechanical properties of stabilized soils on the example of a pilot production site in the central region of St. Petersburg. The proposed method makes it possible to ensure the absence of technological deformations from the production of injection works by using the author's kinematic scheme for the production of works and the use of modern solutions based on fine binders in the impregnation mode with an element of soil microfracture, that is, in the mode of controlled hydraulic fracturing at a reduced injection pressure of the injection solution.

**Construction and Geotechnics**. 2023;14(2):37-50

Effectiveness of compensatory injection as a means of regulating the stresses in complex geotechnical conditions

#### Abstract

Deep excavations in dense urban areas often result in additional settlement of buildings that fall within the influence area of new construction. The most sensitive to such settlements, according to the normative literature, are historic buildings. One of the ways to regulate additional building settlement in the influence area of deep excavations is compensatory injection. The hydraulic fracture network created in the foundation creates additional lateral compression of the soil and changes its physical and mechanical properties. The article deals with a real example of an emergency situation at one of the objects in Tyumen, where during excavation of a pit with the designed depth of 7 meters for the construction of a five-storey building with an extended two-level underground space significant excessive settlement of the adjacent historic building and damage to its bearing structures were revealed as a consequence of the additional settlement development. The purpose of the present study is to evaluate the effectiveness of compensatory injection using collar technology to reduce excessive additional settlement of buildings in the zone of influence of deep excavations. A comprehensive analysis of the impact of new construction on the surrounding environment has been carried out by the authors of the article by means of numerical simulation. Analyzing the results of numerical modelling, the authors of the article developed measures to eliminate the emergency situation and stabilise the foundation. Based on the results of geodetic monitoring, it was found that the installation of a geotechnical barrier by injecting soil using the collar technique not only stabilised the foundation but also brought the building into position to meet regulatory requirements.

**Construction and Geotechnics**. 2023;14(2):51-62

Solution of filtration problems of construction geotechnology in thin water layers

#### Abstract

Filtration problems of construction geotechnics during water movement in thin permeable layers of soils and artificial materials are considered. Under such conditions, traditional approaches borrowed from classical hydrogeology give errors. This is due to the fact that under normal conditions of underground aquifers of a sufficiently large depth, in hydrogeological practice, the hydraulic theory of filtration is used, in which the velocities of filtration currents are averaged along the vertical coordinate. The original nonlinear differential equations of filtration flows are subjected to forced linearization by one or another known method. In this case, the method of linearization by introducing the average power (depth) of the filtration flow is widely used. This method was originally developed for aquifers of great depth. In the presented work, an attempt was made to abandon such a linearization and solve some of the problems of unsteady filtration flows in thin aquifers, which are characteristic of building geotechnics, with obtaining analytical solutions of the final form without introducing artificial simplifications. A methodology is proposed for combining analytical and numerical methods in the process of finding solutions to filtration problems of construction geotechnics with obtaining self-similar dependencies. This approach will make it possible to avoid linearization errors and carry out filtration calculations in thin permeable layers of soils and artificial materials more accurately. A review of domestic and foreign scientific publications on the topic of research has shown some stagnation in this direction. The comparison revealed that in thin permeable layers of soils and artificial materials, preference can be given to filtration calculations using the presented method, since it more accurately describes the non-stationary movement of water in construction geotechnics.

**Construction and Geotechnics**. 2023;14(2):63-74

Experimental investigation of surface roughness changes of an underground structure's material during its driving into the ground

#### Abstract

The mechanical interaction between dispersed soils and the surface of underground structures is fundamental in generating their load-bearing capacity. The technical and economic efficiency of piles and supporting structures depends on the friction forces that appear on the contact of their material with the soil. One of the main factors which has a significant influence on friction forces is the roughness of the material surface. Installation of underground structures, such as pile driving or vibro-driven sheet piling, is accompanied by long periods of material contact with dispersed soils: some structural segments can slip on the soil for tens of metres. As a result, it is likely that the surface properties of the underground structure material will change during this process. Although there is a considerable amount of tribological research, the methodology of such experiments does not fully represent the pile driving process in the soil mass. This means that it is not possible to accurately estimate the change in the surface properties of underground structure materials as they are driven into the soil using the results of these studies. The present paper describes a simulation of an underground structure made of three different materials: steel, fibreglass and fluoroplastic; in fine medium sand. The roughness of the materials was monitored while they were moving in the sand. It was found that with increasing diving depth the roughness of each material becomes less. And the value of this change is influenced by such material properties as material density, shear strength and hardness.

**Construction and Geotechnics**. 2023;14(2):75-91

Numerical determination of the value of the calculated resistance of the base under the stamp of final stiffness, taking into account the rigidity over the foundation structure

#### Abstract

The task set in this study is to determine the values of the generalized strength parameter of the soil of the base σсв R , at which the depth ∆Z of the development of coulomb areas of plastic deformations under the edges of the foundation of final stiffness with a thickness H , loaded with a uniformly distributed load of variable intensity q, and a foundation of the same thickness bearing a rigid over the foundation structure of variable height H * will not exceed a quarter of the width of the foundation 2 b , that is, the values of σсв R , at which the calculation of the base sediment can be carried out in an elastic setting. As a result, it was established that the numerical values of the values σсв R * and σсв R , provided that 2 b H ≤6 and φÎ[20о-35о] do not differ significantly from each other, however, with other values of 2 b H , their difference becomes very significant. If 2 b H ≤6 , then the influence of the value EE о on the numerical values of σсв R * and σсв R can be neglected when performing engineering calculations, using the corresponding values σсв R or σсв R * . If the value of the reduced cohesion pressure is determined σсв =c( γо Htg φ) -1 , as some generalized indicator of the strength of the fixed soil, then using the graphs shown in Figures 3 and 4, it is possible to determine the values of σсв R * and σ св R , comparing which with the value of σсв , it can be concluded whether or not it is possible to calculate the sediment in a linear formulation. Focusing on the numerical values of σсв R * and σсв R , it is possible to determine the values of γо ; φ; c ; E о , which must be obtained in the process of fixing the soil base, so that the given external load does not exceed the value of the calculated resistance.

**Construction and Geotechnics**. 2023;14(2):92-104

Mineral resource base of Kazakhstan for the production of window glass

#### Abstract

The chemical compositions of natural and man-made raw materials of Kazakhstan: quartz sand, quartzite, aluminum, calcium and alkali-containing components used in the production of window glass are investigated. According to the chemical composition, all quartz sand deposits meet the requirements of GOST, except for the content of iron oxide. To use quartz sands in the production of flat glass, it is necessary to enrich them. Chemical compositions of feldspar, quartz-feldspar, pegmatite, kaolin have been studied. Deposits of high-quality feldspar raw materials have been found in the Khantau, Maikul deposits (Zhambyl region), in Kostanay (Bisembaevskoye and Marinskoye pegmatite deposits) and Akmola regions (Zerendinskoye field). Alekseyevsky kaolin is of interest, with a high content of aluminum oxide (38.2 %) and a low content of iron oxide. There are quite large reserves of limestones and dolomites in the Republic of Kazakhstan, including the Karatau, Talgar and Shieli deposits. Reserves of chalk with a calcium carbonate content of 94-98 % and insignificant iron oxide are available in the Mangistau region. Kazakhstan has deposits of natural sodium sulfate in the form of solid deposits and brine of numerous lakes. The phase composition of local quartz sands and feldspar has been studied by X-ray phase analysis. Compositions have been developed and experimental glass cooking has been carried out. The content of silicon oxide as the main component in the initial quartz sand is 99.1 %, and the coloring glass of iron oxide is 0.08 %. Therefore, the enrichment method was used to reduce the content of iron oxide in the sand.Studies have shown that magnetic separation can reduce the Fe2O3 content from 0.08 to 0.06 %, by washing from 0.08 to 0.05 %, by flotation to 0.03 %. The size of quartz sand is within the limits that do not complicate the glass cooking process:the content of large grains larger than 0.8 mm is 0.3 %, small grains smaller than 0.1 mm -3 %. The mass fraction of the heavy fraction with a density of more than 2900 kg/m3 is -0.2%. According to complex indicators, the sand corresponds to the VS-030-1po GOST 22551-90 brand. The characteristic intervals of changes in the viscosity of cooking, production, molding, annealing and the corresponding temperatures are determined. The values of the physico-chemical and technological properties of the glasses were obtained by the calculation method. A schedule of annealing of flat glass has been developed.

**Construction and Geotechnics**. 2023;14(2):105-115

Construction information model as a tool to reduce information uncertainty in the operational management of construction

#### Abstract

The construction of capital construction projects is a complex probabilistic dynamic system subject to numerous external and internal factors. With the complexity, uniqueness of the construction object or constrained conditions for the production of work, the number of such factors increases, as a result, information uncertainty in construction management increases, which leads to a decrease in the effectiveness of the use of traditional organizational and technological models. It is required to search for new and improve existing models. One such model is the construction information model. The purpose of the article is to substantiate the reduction of information uncertainty in the operational management of construction by changing the structural links in the construction management system and the use of a construction information model as a dynamic organizational and technological model. The transition to information modeling technologies requires the main participants in the investment and construction project to change the form of interaction, as well as changes in communication patterns in the structures of individual organizations. For example, the management of construction organizations should continuously manage construction using a building information model. The organizational structure in which the building information model is used positively affects the following aspects of the control system: reduces transaction costs between departments and services; provides high information content; improves the consistency of information between services by analyzing data from a single source; speeds up the decision-making process; increases the stability of the management system, taking into account external and internal factors; enhances organizational reliability. The significance of the presented results for the construction industry is to reduce information uncertainty in the operational management of construction by changing the structural links and information transfer scheme, as well as the continuous collection, storage and analysis of information coming from the construction site into a single construction information model.

**Construction and Geotechnics**. 2023;14(2):116-127

Application of visual programming for automation tasks in construction

#### Abstract

Modern architectural and structural design is focused on the use of computational capabilities of computers and the use of software. The issue of design process automation is very urgent because of limited capabilities of software complexes and high labor costs for elaboration of solution options. Visual programming is the most accessible tool for scripting to automate the design process in applied software complexes. However, information about this tool in special literature is scattered and unstructured. The aim of this article is to review the spheres of visual programming application in design, to systematize and structure the information and to compare it with alternative tools. For this purpose, we collected and analyzed the relevant literature from the databases of scientific publications. A classification of design approaches in which visual programming is applied has been compiled. Taxonomy and definitions for terms denoting such approaches as parametric, generative and algorithmic design have been proposed. Comparison of visual programming with alternative tools for automating the design process has been carried out. The tasks of design, for which it is rational to apply visual programming, have been singled out. A promising direction of application of this tool is the creation of user plug-ins for software systems.

**Construction and Geotechnics**. 2023;14(2):128-143

Training sample balancing to train artificial neural networks for geotechnical problems

#### Abstract

This paper deals with the issue of balancing the training sample for training artificial neural networks when solving geotechnical problems. As an example problem, the prediction of mechanical characteristics of soil based on physical parameters is considered. A multi-layer full-connection artificial neural network was used to build the dependence. The need to improve the accuracy of analytical calculation methods for geotechnical problems is constant. Recently, such a regressor as an artificial neural network has been used more and more often for geotechnical problems. Neural networks are a powerful forecasting tool that allows reproducing dependencies of almost unlimited complexity. As neural networks need to be trained on a ready set of data, there is a question of quality of geotechnical test databases that are used for training. Due to the fact that there is no centralized way to collect geotechnical test data electronically, many researchers encounter significant incompleteness and imbalance in the data when attempting to collect such data. This paper proposes a solution for balancing such a training sample by generating examples of minority classes. It is proposed to balance the sample by generating missing examples with random parameter values within a certain range. The output data is proposed to be obtained with the help of existing calculation methods. This approach made it possible to make the training sample evenly distributed over the entire available range of values. At the same time, the range of predicted values increased in accordance with the limits of the experimental and generated sample. In addition, this approach allows us to take into account the existing analytical calculation methods when training neural networks.

**Construction and Geotechnics**. 2023;14(2):144-153