Table of contents

Journal of Physics: Conference Series

II ALL-RUSSIAN CONFERENCE WITH INTERNATIONAL PARTICIPATION

Deep foundations and geotechnical problems of territories, DFG 2021

Perm National Research Polytechnical University, Perm; Russian Federation; 26 - 28 May 2021;

Editorial Preface(Editorial) Open Access Vatin N.^a, Borodinecs A.^b, Abdikarimov R.^c

^aPeter the Great St. Petersburg Polytechnic University, St. Petersburg, Russian Federation ^bRiga Technical University, Riga, Latvia ^cTashkent Financial Institute, Tashkent, Uzbekistan

The current 2nd All-Russian Conference with international participation "Deep Foundations and Geotechnical Problems of Territories" (DFG 2021) was successfully held in Perm, Russia, at the Perm National Research Polytechnic University from May 26 to 28, 2021.

A key aspect of this conference is the strong confusion of academia and industry. This allows the free exchange of ideas and challenges faced by these two key stakeholders and encourages future collaboration between members of these groups.

The conference was organized by the Perm National Research Polytechnic University, the Russian Academy of Architecture and Civil Engineering, and the Russian Society of Soil Mechanics, Geotechnics, and Foundation Engineering.

The main goal of the conference is to promote research and development in advanced research in the field of geotechnics, and the other goal is to facilitate the exchange of scientific information between researchers, developers, engineers, students, and practitioners working around the world.

The conference model was divided into four sessions, including oral presentations and keynote speeches from invited speakers. Key reports were presented by leading experts from France, Germany, Russia, Italy, Turkey, Kazakhstan, and Uzbekistan. The speeches were accompanied by a simultaneous translation and lasted up to 40 minutes. Then the work continued in four sections, where the speakers were given up to 15 minutes to speak. The conference included 69 reports from more than 200 authors, as well as 20 poster presentations. The conference was attended by over 100 people, including online.

The conference was held in a mixed-mode. Most of the participants took part in the conference directly, the other part was online. The latter was associated with the epidemiological situation in Europe and Russia. Which of course made it difficult to communicate between specialists and worsened the lively climate of communication.

Key lectures at the conference were delivered by Professor Zhusupbekov A.Zh. President of the Kazakhstan Geotechnical Association (Eurasian National University, Kazakhstan), Professor E. Guler (Bosphorus University, Turkey); Professor - Manassero M., Vice President of ISSMGE for Europe, Professor (Turin Polytechnic University, Italy); Professor Katzenbach R. (Darmstadt Technical University, Germany); Professor Varaksin S., ISSMGE TC211, (France); Professor of the Prague Technical University I. Vanicek (Czech Republic).

During the conference, modern geotechnologies for the construction of foundations and foundations in various soil and climatic conditions, including in potentially dangerous areas, were discussed, as well as modern methods of engineering surveys and testing of newly erected objects. Practical experience of strengthening the foundations of existing buildings and structures. New materials and technologies in road construction are presented. The results of experimental and theoretical research in the field of geotechnics and foundation engineering, methods of modeling, and calculations of foundations and foundations are discussed.

The proceedings of the conference are a collection of accepted articles and represent an interesting outcome of the conference. Topics include, but are not limited to, the following areas: laboratory and field testing of soils; experimental and theoretical studies of foundations and underground structures; technology of the device, strengthening of bases and foundations; the practice of development of underground space, geotechnical monitoring, geosynthetics in geotechnics.

The exchange of views on topical issues of fundamental structures contributes to the development of geotechnics, strengthening and expansion of communication between experts in the field of soil mechanics and geotechnics in Russia and abroad.

All papers published in this volume of Journal of Physics: Conference Series have been peer-reviewed through processes administered by the Editors. Reviews were conducted by expert referees to the professional and scientific standards expected of a proceedings journal published by IOP Publishing.

• Type of peer review: Double-blind for most papers / Triple-blind for some papers

• Conference submission management system: EasyChair

• Number of submissions received: 87

• Number of submissions sent for review: 77

• Number of submissions accepted: 69

• Acceptance Rate (Number of Submissions Accepted / Number of Submissions Received X 100): 69/87x100=79,3

• The average number of reviews per paper: 2.1

• Total number of reviewers involved: 24

• Any additional info on the review process: The articles were reviewed by leading experts in the field of geotechnics from Germany, Kazakhstan, Uzbekistan, the Czech Republic, and Russia.

• Contact person for queries:

• Name: Andrey Ponomaryov

• Affiliation: Professor, D.Sc. Perm National Research Polytechnic University

• Email: andreypab@mail.ru

Since 2001 the so called Hafencity arises in Hamburg, Germany. Currently it is europes biggest urban development project. So far the most famous building of this area is the well known Elbphilharmonie. Now another impressive building is in planning – a huge skyscraper. The new skyscraper will get an over all height of 245 m. Due to the little bearing capacity of the ground a deep foundation is needed. To found the building Germanys deepest foundation piles, with length up to 75 m, will be executed. In advance, to determine the bearing capacity of the surrounding soil, four testpiles, with lengths up to more than 110 m, have been executed.

Originally geotechnical engineering is connected with ground with rock and soil environment, focused on geotechnical structures which are in interaction with ground, and therefore we often speak about construction on, with or in ground. However, during last decades, especially with increasing focus on environment protection, geotechnical engineering is dealing also with other materials, denoted as alternative aggregates. They are mostly a byproduct of mining or industrial activities for which a method of future use is being sought. Typical examples are fly ash, construction and demolition waste, slag and different tails from chemical treatment of target ores which have similar character as natural soil and are produced in large volumes. Therefore, there is legitimate question about their possible use in earth structures, preferably of transport engineering. If external circumstances (e.g. distance of origin from the place of use) are favourable, geotechnical engineering is focused on two basic aspects - on possible negative impact on environment due the chemical composition of leachate or on structural stability. If there is no opportunity for their further use we have to guarantee safe deposition. In this case we are speaking about earth structures of environmental engineering as tailing dams, spoil heaps, landfills and are responsible for their safety. The paper is therefore focused on three main problems: Utilization of alternative aggregates (e.g. large volume waste) in transport engineering; Problems of earth structures of environmental engineering, where large volume waste is stored, as e.g. tailing dams and Structural collapse of tails studied in micro scale in laboratory.

Mineral waste has become not only the largest waste stream in many countries, but also a reliable source of material to replace primary raw materials. Much of this material is already being used successfully. However, the potential of many materials such as slag or ashes, is currently not fully unlocked as this kind of material is used only for backfilling, often referred to as downgrading. In this study, the use of recyclables in higher value applications was investigated. In several laboratory tests, the usability of substitute building materials (SBM) in green applications, such as green roofs, green facing elements or fill material in (geogrid) reinforced soil structures ((G)RSS), was tested. The study concept includes both, soil mechanical laboratory tests and greening tests on SBM. The greening tests showed that broken bricks are suitable when mixed with organic materials. Pure brick rubble material can only be insufficiently greened. Chemical and soil mechanics tests were carried out with the fill materials. Some materials such as Lignite fly ash were excluded from soil mechanical tests because of insufficient chemical properties. These materials are not suitable for building applications without a sealing layer. Many other materials, such as recycled concrete or different kinds of slags have equivalent or even better soil mechanical properties than primary materials. Many of these materials also have chemical properties that allow almost unlimited use in construction.

Based on the laboratory results, the construction of an RSS with complete substitution of the primary building materials will be started as a large-scale pilot test in the next step.

The article provides a solution to the problem of the stress-strain statement of a soil mass with excavation, under the impact of a deep foundation. The solution to the problem is obtained by integrating Melan's solution. The final expressions for the stress-strain statement components are presented. Isolines of stresses in the soil massif and reactive forces of enclosing wall structure are also given.

The statement and solution of problems on the interaction of incompressible barrette with the soil massif as part of a pile-raft foundation are considered, taking into account the barrette steps, diameters, the embedded length, as well as nonlinear soil behaviors by analytical and numerical methods using Plaxis-3d. It is shown that these parameters have a significant effect on the stress-strain state (SSS) of the soil massif interacting with the barrette-raft system. By taking the approach above engineers entirely manage to gain formulas so that to determine the SSS in incompressible barrette, as well as to assess the settlement of this system. For the sake of achieving the solution to problem above, the behaviors of the barrette-raft system, the soil massif are assumed to be elastic.

Jet grouting is a relatively recent development which is applied for mainly ground improvement purposes and provides effective solutions to many geotechnical and geoenvironmental problems. Jet grouting technique differs substantially from the other grouting techniques in that this technique can be used in treating a wide range of soil types. Therefore the application fields of jet grouting are rapidly increasing. The main emphasize in this paper is given to the strength properties of jet grout columns. The strength properties of jet grout columns is investigated by the example of five case studies. The subsoil conditions and foundation engineering evaluations of the investigation areas are presented in the case studies. The strength properties are investigated by referring to the unconfined compressive strength test results of the core samples obtained from jet grouting columns.

The company FM Logistic plans to build a warehouse about 40 km at east of Moscow. Total area of the future project is 149 615 m². Compressive soil layers have been identified by the soil investigations. The main purpose of this article is to illustrate soil improvement solution in order to ensure the bearing capacity and to limit the absolute and differential settlement to allowable values.

Although conservative estimates of the containment performance of bentonite-based barriers can be obtained from the classical advective-diffusive transport theory, the semipermeable properties of the bentonite component can determine a significant reduction in the migration rate of contaminants at low salt concentrations (< 100 mM). After introducing the transport equations for a semipermeable porous medium, the paper presents the laboratory testing apparatuses and procedures that allow the chemico-osmotic efficiency coefficient, ω, and the osmotic effective diffusion coefficient, D^*_ω, of bentonites to be experimentally assessed. Finally, the advantages that derive from the ability to model the semipermeable behaviour of bentonites in the design of geoenvironmental barriers are discussed with the aid of a calculation example, which considers the use of geosynthetic clay liners for the bottom lining of waste disposal facilities.

The analysis of the soil area in the base of an absolutely stiff building has been proposed in the article. Influencing this area it is possible to correct the tilt. The authors of the paper provide an overview of various methods of the tilt correction. The study of the soil spreading in the basement soil has been carried out; the soil area is less deformed under eccentric loading than under central loading. This area is proposed to be called the area of "deficit" strains. The first series of numerical computations has shown that this area depends only on the tilt of an absolutely stiff building; it is described in accordance with a linear law when using simple geometric shapes: a sector and a segment. The second series of computations has illustrated that when decreasing deformation and strength characteristics of this area, the building tilt is corrected. In here, the entire area of the "deficit" strains is not required to be used, just its basic area incorporating a part of a sector and a segment. These areas are concentrated at the edge of the footing. The optimal range of values for a single coefficient which lowers the basic mechanical characteristics of soil has been established. Conclusions on the computations have been drawn and plan for further research has been proposed.

The paper presents the experience of building and structure strengthening in Tyumen soil conditions which are often presented by a soft water saturated clay and sand layer of the quaternary period. All buildings mentioned in the paper had uneven settlements due to complex engineering and geological conditions and the wrong choice of foundation type. Thin drilled injection piles with a diameter of 200 mm were used for foundation strengthening. All the piles were installed on the solid soil base during the drilling process regardless of the depth of its location. No rules have so far been approved to calculate the bearing capacity of thin drilled injection piles. That was the reason for defining the drilled injection pile bearing capacity at every facility. The paper describes the methods and test results obtained in the study. It was found out that all piles had unexpectedly high bearing capacity. The paper also contains the results of geotechnical monitoring before and after base building strengthening by drilled injection piles which show the current decrease of settlements and the efficiency of this base strengthening method.

An end bearing stone column is one of the most common types of stone columns, which completely penetrates through a layer of soft clay soils, resting on much stiffer soils. This article presents a numerical model (analyses) of the stone column used to strengthen the soft clay soil. The analyses were performed using a three-dimensional model in FLAC3D. To investigate the effect of the stone column on strengthening soft clay soils, a dimensionless parameter called the settlement improvement ratio (K_s) is used. The results show that, the settlement improvement ratio (K_s) increases with an increasing diameter of the stone column. The lateral deformation of the stone column decreases with the increasing stone column diameter, and the maximum lateral deformation was occurred at approximately (1.0 to 1.5) diameter from the top of the surface.

In a cold climate design of dams, clay barrier liners on landfills, and structures on frost-susceptible soils is a challenge for geotechnical engineers. During service life of the structures a frost heave may reach 15-20% of the depth of a frost penetration and an uplift movement are accompanied by the formation of layered or lattice cryogenic texture. When thawing, macro- and micropores are formed instead of ice lenses. Basically pores are oriented predominantly along frost front. They are a reason of horizontal water permeability increase, consequently, reduce of stability of the slopes and decrease of the effectiveness of the landfill clay barrier liners. The paper presents a new apparatus for studying water permeability and frost heave of soils which allows to carry out horizontal or/and vertical permeability tests (along and across layered cryogenic texture) after assigned number of freeze-thaw cycles without withdrawal of a soil sample from apparatus. The results for clay and fine sand samples are obtained. Clay and fine sand samples showed an increase of horizontal hydraulic conductivity after 2 - 4 freeze-thaw cycles. Relationship between water flow velocity and hydraulic gradient for non-Darcian and Darcian flow is obtained as a result of vertical permeability tests of clay samples in unfrozen state.

The authors propose a combined approach for definition of the shear rigidity of the multilayered soil which is cut through by a pile. The 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 rigidity of the wide pile field in condition of dynamic forces action. The 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. To speed up calculations at the stage of the main combination of constant and long-term impacts, the vertical rigidity of the base under the foot of the pile can be calculated analytically as for a stamp on an elastic-plastic base. The horizontal rigidity is considered as for a discrete single bent pile in the medium of an elastic layered half-space at the stage of formation of the stress-strain state of the system under the main combination of static loads. At the final stage of short-term or special load, a transition to the integral shear rigidity of a pile field is proposed.

Modern non-destructive techniques of wave analysis can be applied for the express preliminary geotechnical soil assessment. One of them is Multichannel Analysis of Surface Waves (MASW) which allows obtaining velocities profile of shear waves and the initial shear modulus for the upper section promptly and at minimal labour costs. However, the soil deformation properties assessment requires the deformation modulus that is obtained by the direct technique of plate load test (PLT). The purpose of the study is to assess the correlation between the PLT deformation modulus and the initial shear modulus determined with MASW.

Excavation of pits, trenches for foundations of civil buildings and industrial structures in saturated clayey soils often leads to soil structural change and great decrease in the soil strength and deformation characteristics. In some cases, an artificial sand base is used as a method for construction on saturated clayey soils. However, technology violations and unsuitable material used during construction can be the reason for excess settlement of the erected facilities. The study includes a real example of an emergency situation at gantry crane railways with three hundred meters in length in the town of Tobolsk. The artificial base was made using local sand with specific properties such as subsidence and frost heaving, which were not taken into account in the design process. The observed excess non-uniform base deformations were up to 240 mm. The base properties of the silty sand were analyzed in a laboratory study. Two tests were carried out to simulate possible impact on the artificial sand base. They showed that the values of the initial compaction factor K_com of sand base were found in the range of 0.87-0.92. So, the base subsidence was about 12% of the actual base deformation and the total base settlement under the total operation loading made about 19%.

The article analyzes the current state of the landslide slope of the river Oka, an assessment of landslide risks was made. Various models of ground base behavior in flat setting in the current state and taking into account prospective development are considered. A geometric model of the slope was simulated, using the software complexes "Plaxis" and "GeoStab," factor of safety and critical sliding surfaces were determined, various anti-landslide designs for maintaining the stability of the slope were considered, technical solutions for performing landslide control were proposed.

The article presents the results of analyses of more than 500 samples of phosphogypsum, which is the waste in the process of phosphorous fertilizers production, consisting of calcium sulfate with admixtures of sulfuric and phosphoric acids, silica and other substances. The characteristics of hemihydrate phosphogypsum (CaSO₄0,5H₂O), in which cementation bonds form as the hydration process proceeds, were studied on undisturbed samples taken in 1 and in 6 months, 1, 5 and 10 years after the material was dumped. It is characterized by low strength and insignificant frost-resistance, which is typical for all building materials and products based on gypsum. The cementation bonds have not been formed in dihydrate phosphogypsum (CaSO₄-2H₂O) and it remains a non-cohesive granular substance in the dump, so its properties were determined by the methods used in a geotechnics for sands and silty soils. The artificially prepared samples with the relative compaction of 0.80, 0.90 and 0.95 were tested. While the obtained values of the internal friction angle, cohesion and hydraulic conductivity were characteristic for fine sands, the compressibility of this material due to the solubility of the particles was substantially higher. The utilization of phosphogypsum as ground material may have limited use, provided that water protection measures are taken and the acids contained in it are neutralized.

The article presents the results of studies by the numerical method of pile and slab foundation with a reinforced base by the method of deep soil mixing (DSM) under the influence of seismic loads using the LIRA-SAPR software package, which implements the finite element method. The parameters of the computer model are presented, which make it possible to obtain the calculation results. A comparative analysis of the calculation results is carried out. In the course of the study, it was revealed that the use of a slab foundation with a reinforced base by the deep soil mixing method (DSM) is more effective than a pile foundation under seismic loads.

The article presents the results of static load tests of a strip foundation fragment (bearing plate) underpinned by a drill-injection pile, which has a widening low at its lower end. The static load tests were carried out at the experimental site in the city of Tyumen. A drill-injection pile with widening low end is an injector that has a rubber membrane-glass at its lower end. With the help of a hydraulic packer, the solution is injected into the rubber membrane-glass. After the solution has cured, a widening low end of the required volume is formed at the lower end of the injection pipe. To assess the results obtained, static load tests were also carried out both for a strip foundation fragment without underpinned using a drill-injection pile with widening low end, and a separately located drill-injection pile with widening low end. Based on the data obtained during static load tests in the course of the experimental study, graphs of dependencies were formed: the settlement of a strip foundation fragment on the pressure under its base and the settlement of the drill-injection pile with widening low end on the static load. As a result, it was found that the use of a drill-injection pile with widening low end to underpin a strip foundation fragment allows increasing the bearing capacity by an average of 30%.

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 – geobulk – 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.

Introduction: During constructing tunnels by trenchless method using the shield driving method soil surface subsides. Buildings and structures which fall into the zone of influence of new construction receive additional settlements. To determine it in the calculations it is necessary to take into account the excess excavation ratio. The purpose of the study is to determine the excess excavation ratio for increasing the sample and determining the normative values of the ratio for application in design.

Materials and methods: in the article there is examines the construction of a tunnel in the city of Moscow. Calculations are carried out using the PLAXIS software package in two-dimensional and three-dimensional formulations. In the calculations the normative excess excavation ratio was included and a backward calculation was also carried out in order to determine the actual excess excavation ratio according to the data of geodesic monitoring. Results: the results showed that the excess excavation ratio varies from 0.1% to 1.2%. It is much less than the values that are included in the project according to the regulatory documentation.

Conclusions: due to the fact settlement is less than the calculation settlement, the cost of building tunnels can be reduced by reducing the cost of protective measures for buildings and structures, as well as reducing the number of buildings that can receive excess settlement.

Construction of facilities in cramped conditions requires a special approach connected with the development and implementation of measures to ensure safe operation of the surrounding buildings within the geotechnical influence. Builders often neglect the impact of a new facility construction technology on possible negative effects resulted in the existing buildings (cracks on the facades due to uneven settlement, tilts, etc.). So far the concept of a minimum price has been used when erecting a building part below the zero mark. This approach completely ignores the notion of engineering viability. At the same time builders resort to every kind of trick to reduce the cost of construction. Such an irrational method may eventually result in a substantial increase in the cost of the zero building part construction. As a rule, it can increase the construction time (agreement on a new project when replacing it with another geotechnical technology, and undergoing new expert review). This paper examines a negative case from the geotechnical practice of constructing a 16-storey residential house next to the existing five-storey one.

The issue of strengthening weak or overloaded bases is an important task for the development of underground space. This is especially true in the presence of alternating weak layers at the base. The paper considers a case from the geotechnical practice of strengthening the overloaded base of a reinforced concrete foundation plate of a 25-storey residential building under construction.

Combined ground piles consisting of Get (type 1) ground concrete piles reinforced along the longitudinal axis with made drill-injection piles using electric discharge technology (EDT piles) are used as buried structures. This method of arrangement of a combined buried reinforced concrete structure is due to the need to increase the load-bearing capacity of the pile on the ground by two times or more

The article presents the results of the practical applications of screw piles foundations for block quick-assembly buildings and buildings made of a metal frame. The results of experimental and theoretical studies of foundations in various ground conditions are presented. A method for estimating the stress-strain state of screw pile foundations using nonlinear calculation methods is proposed. The influence of pile length and blade diameter on the change in displacements and load-bearing capacity in cohesive and non-cohesive soils on the effect of pushing and anchor loads is revealed. The nature of the distribution of stresses and deformations at the base of foundations made of screw piles is revealed. The article is useful for engineers, specialists and researchers in the field of soil mechanics, foundation engineering and geotechnics.

In the interests of sustainable development of the country, improving the quality of the living environment of the population, ensuring environmental safety, it is necessary to create scientific and technological potential, which is noted in the Decree of the President of the Russian Federation and the Resolution of the Government. Based on the foregoing, this article discusses the issues of improving shell structures, composite nanomaterials, their reliability, longevity and stability in natural climatic, technogenic, social and environmental factors. A feature of the above shell structures is their ability to maintain their design shape after various influences, which is laid down in the design and technological processes. The use of shell structures made of various composite (fabric, metal-cord and rubber-fabric, etc.) materials was most widespread in the 70s and 80s of the previous century, which is characterized by the creation of various scientific schools: Sergeev B I - soft hydraulic structures; Petrakov B I -pneumatic dams, pneumatic formwork; Blinov Yu I - awning structures; Ermolov - pneumatic building structures; Stepanovich G Ya, - retaining structures for mine workings, etc. Significant successes in the creation of composite materials were made by foreign firms (Japan, Italy, USA, England, etc.).

Nowadays, it is a common practice to erect buildings and structures on base soils, which were previously compacted in various ways. During this process, the physical and mechanical properties of the following base soils are changed in order to increase their bearing capacity. In this article, on the example of some construction sites, test studies of the physical and mechanical properties of soils are described. Some results of these studies, both before and after soil compaction are given. Physical, deformation and strength characteristics were determined in both laboratory and field conditions. During the work, the following objectives were set: to conduct full-scale (field) and laboratory studies aimed at reliable determination of the strength and deformability characteristics of compacted sandy soils; to analyze the characteristics of compacted soils that determine the development of deformations over time; to conduct experimental field and laboratory studies on the use of compacted sandy soils of various granulometric composition and density as the structure base; to establish a set of controlled parameters of the compacted soils properties on the basis of conducted analytical studies. Thus, the object of the study during this work was sandy soils with different granulometric composition. The conclusions were drawn on the results of the work.

The article describes the concept of combined strip pile foundations with prestressed soil bases by pressing them with the cement mortar. The soil base pressing makes it possible to regulate and control the soil stress-strain state by creating prestresses that allow increasing the rigidity of the soil base and reduce the level of the base settlement and deformations of the above-ground part, the values of which determine the operational suitability of structures and their technical and economic indicators. The authors present the results of the applied combined strip pile foundation implementation in Tyumen (Russia) during the construction of two 22-storey high monolithic-frame apartment buildings as an alternative to pile-raft foundations based on composite driven piles, which helps to reduce the estimated cost and timing of the foundation constructions. Also the article describes the construction operations and contains the geotechnical monitoring results, which confirmed the operational reliability of the implemented solutions.

Rasskazov L.N., Bestuzheva A.S., Sainov M.P., CHernysh A.S., Francesco Castelli and many others were engaged in studies of the stability of slopes under seismic impact. The paper considers numerical methods for assessing the seismic stability of embankment dams in a flat and three-dimensional problems in two ways: a direct dynamic method and a pseudo-static method. Several simulation cases are considered in a flat problem on a test problem using soil properties taken from a real site of an operating hydroelectric power plant. During the simulation, the following main simulation cases were considered: the natural stability; calculation without static components; calculation with static components; impact of free vibrations; calculation with full accelerogram; calculation with static deformation properties of soils; calculation with dynamic deformation properties of soils; calculation with undrained strength of soils; pseudostatic method. The analysis of the results showed that the calculation of the seismic stability of an embankment dam by the direct dynamic method gives the results that are closest to reality, in contrast to the pseudo-static calculation method.

The paper considers main reasons of strengthening foundations and base soil stabilizations of used buildings. We analyzed more than 120 buildings with various design solutions, which were operated mainly on clay soils, identified reasons and divided them into four groups. The first group is reconstruction of buildings, including their restoration and complete overhaul. The second group is the material destruction of the foundations and a decrease in their waterproofing qualities. The third group is a violation of the stability conditions of foundations during the operation of buildings (structures). The fourth group is the development of significant deformations of buildings during their operations.

This article presents the results of studying the influence of the enclosing structure of the pit, made according to the technology of the reinforced concrete wall in the ground of the trench type, on the heeling of a high-rise building on a raft foundation. The study was performed using the numerical method with the PLAXIS 2D software package. The influence of the wall in the ground on the building roll was determined depending on the distance from the wall in the ground to the edge of the raft foundation of the building, the embedding depth of the wall in the ground below the bottom of the excavation and the characteristics of the contact element. The degree of influence of each of these factors on the heeling of the raft foundation was determined by the factor analysis based on the theory of experimental planning. The mosaics of deformations of the soil massif at the base of the raft foundation are given, as well as graphs of the dependence of the change in heeling for the considered factors of influence. According to the study results, the boundaries of the significant influence of each of the factors considered, as well as the walls in the ground as a whole on the heel of the building are determined. The issues are discussed on applications of the study results to reduce the heeling of high-rise buildings at the design stage.

The article represents crack control research results of horseshoe-shaped fibre reinforced concrete tunnel linings which are constructed by conventional tunneling method on a full cross-section in rocks. Based on linear fracture mechanics an alternative method for estimation of the crack resistance for such kind of linings is proposed. The research was carried out by using the finite element method supported with experiment planning method.

Using reinforced bases in clay soils is studied still insufficiently well. Therefore, in order to use the building practice of constructions of the bases on the reinforced ground it is necessary to carry out the analysis of their is stress-deformed condition to reveal a rational scope and to develop optimum constructions of the reinforced bases. For studying of work of the reinforced bases complex theoretical experimental researches have been carried out: laboratory modelling researches, natural tests, numerical modelling of work of the reinforced bases in water sated clay soils. The tests revealed that the single layer reinforcing clay base results in an increase in bearing capacity of 1.35 times the base. Effectiveness of reinforced bases increases with increasing precipitation structures. Stress-strain state reinforced base is markedly different from the stress-strain state of reinforced base. Introduction reinforcing element transforms the stress distribution in the core base. Stresses concentrate in an area of the reinforcing layer and decrease in the area below it. Redistribution of the active area in the vertical stress is reinforced based on depth amount 1.0-1.25 d from the base of the stamp, and in width by up to 1.0 d from the axis of the die. The test results showed high efficiency of reinforcement to increase the bearing capacity of foundations in clay soils. The carried out researches have allowed to receive a qualitative and quantitative picture of reinforced soil work of the bases and their stress-deformed condition to define a rational scope and to develop recommendations or their designing.

In similarity to every civilization in history originated from the riverside, the city of Nur-Sultan, which the new capital of Kazakhstan developed around the Ishim River. During the last 25 years, many high-rise buildings supported by pile foundations are rising in Nur-Sultan. The paper presents the monitoring of development for the unique residential building of 310 m high with 4-story underground parking. The pile raft foundation (for block R) analyses had designed using Geocthenical soft, which can assess in precise of the deformations, occurs in soil. In the paper presidents, method monitoring raft foundations for block R, the height of this block R is 320 meters. Design of distributed fibre optic strain sensing system (DFOSS) has been employed for measuring the strain in civil engineering structures for over a decade. It is now harnessed worldwide for monitoring a wide range of structures slab pile foundation. Geotechnical monitoring data of adjacent building and utility systems settlement caused by the construction of presented high-rise buildings were compared to numerical modelling results, predicted, and permissible values.

Finally, the raft foundation recommended for future high-rise buildings constructed of Nur-Sultan city on complex soils.

The development of renewable energy sources technologies is relevant. Sun radiant energy, wind energy, water energy, earth low-potential energy are main renewable energy sources. Energy foundations are used for earth low-potential energy extraction. The research results this paper presented can be used for energy foundations calculations. It is necessary to know soil thermal characteristics to the energy foundations calculations. At the moment, there are many calculation methods for determining soil thermal characteristics, but none of them take into account their grain-size composition. The research purpose is to assess the dependence sandy soil thermal conductivity on grain-size composition. According to the research results, firstly, the influence of the density and moisture content of the soil on its thermal conductivity was confirmed, and secondly, it was established that, at the same moisture content and density, the size of the soil grains matters. Particle size distribution affects the sandy soil thermal conductivity. With an increase in the particle size, sandy soil thermal conductivity increases.

The main results of the work on the analysis of the possibility of using polyacrylamide drilling muds for the installation of drill piles, barrettes and slurry walls in sandy soils are presented. The results of the study of the possibility of solutions to keep the walls of boreholes from collapse, laboratory studies of the effect of polyacrylamide solutions on the shear strength of soils, as well as the results of field tests of piles with static pulling load are reflected.

The depletion of traditional fossil energy sources leads to an increasing development of non-traditional energy sources. One of the promising directions of alternative energy is the use of low-potential energy of the soil for heating buildings and structures for various purposes. Heat extraction is possible through the use of energy foundation. However, their rational design is impossible without a careful assessment of a large number of factors that affect the potential value of thermal energy extracted from the soil. The purpose of this work was to build a whole methodology to assess the degree of influence of soil thermophysical properties, in particular, such as heat capacity and thermal conductivity, on the amount of heat energy selected energy pile. The formulation and analysis of the numerical experiment to identify the desired dependencies. The matrix of experiment planning is made. The numerical simulation of the energy pile of different geometric parameters in different soil conditions is performed. Statistical processing of the obtained experimental data was carried out. A quadratic regression equation was developed to determine the amount of heat through the side surface of the pile depending on the length of the pile, its diameter, heat capacity and thermal conductivity of the soil. The analysis of this equation for the purpose of estimation of degree of influence of initial thermophysical parameters of soil on value of thermal energy of the selected pile is carried out.

A mathematical model of the problem of viscoelastic isotropic plate vibrations based on the Kirchhoff-Love hypothesis in a geometrically nonlinear formulation was presented. The mathematical model was built without considering the tangential forces of inertia. To describe the viscoelastic properties of the plate material, a weakly singular Koltunov-Rzhanitsyn kernel with three different rheological parameters was chosen. To solve the problem of parametric vibrations of a viscoelastic plate with a weakly singular relaxation kernel, a numerical method based on the use of quadrature formulas was applied. A discrete model of this problem was first constructed using the Bubnov-Galerkin method; i.e., a system of integro-differential equations with variable coefficients was obtained, and then, using a numerical method based on the elimination of a singularity of the kernel, the problem of parametric vibrations of viscoelastic rectangular plates was solved. The influence of the viscoelastic properties of the material and the variability of the plate thickness on the oscillatory process was shown.

The main purpose of this paper is to study the parameters of strength and deformation of clay soil in conditions of triaxial compression under block regime cyclic loading. To date, there are no data on the results of studies under this loading mode. Theoretical and experimental studies of the strength and deformability of clay soil of triaxial compression 0^02=03 under block regime cyclic loads are carried out. A distinctive feature of the experimental studies is that they were carried out in devices of triaxial compression of a prismatic shape with an aspect ratio of 100x 100x200mm. In the study of vibration creep deformations and changes in the fatigue resistance to the destruction of clay soils under triaxial regime block cyclic loading. It is established that the stress-strain state, deformation, and fatigue strength of soil vary depending on the sequence of alternating blocks with different values of the maximum load of the cycle. The developed and obtained equations describing the deformation of the soil under these conditions with the development of micro-cracks observed in experiments of hardening and softening effect of inhibition at different stages of cyclic triaxial compression allow to accurately estimate vertical deformation (settlement) bases under regime loading and to obtain reliable and economical design solutions.

The paper describes the calculation and design steps of deep excavations and foundations of a high-rise building on a territory with a high groundwater level and existing buildings with a physical wear of their bearing structures and foundations located in the zone of mutual influence. The aim is to find a rational solution for the diaphragm wall, pile-raft foundation of the high-rise building in order to protect adjacent objects and consider various factors that determine the nonlinear behavior of subsoil layers and the elements of geotechnical protection. As an example, a project of a high-rise building with a multi-level underground parking located in the central part of Krasnodar is shown. It is designed and calculated considering the staged construction of the pile-raft foundation, non-linear behavior of the subsoil layers, the influence of a variable groundwater level, the risk of technological settlements and liquefaction of the underlying sandy soil layers. Due to the performed researches and by following the construction methods, it became possible to keep the existing buildings and structures safe during the construction period and further operations. The observed methods of construction of the pile-raft foundations and deep excavations in difficult subsoil conditions using the example of the central part of Krasnodar make it possible to recommend the obtained results as a rational solution applicable for similar cases in conditions of a dense urban infrastructure.

Erection of structures on soft soils is a difficult task. The cost of the foundation in such cases can be up to 30-35% of the cost of the entire structure. Therefore, an urgent task is the use of effective foundation structures. The use of reinforcing geosynthetic materials is one such method. The article describes the experience of using geosynthetic reinforcing materials in the construction of the foundation for steel cylindrical vertical tanks with a volume of 630 m3. The results of calculations of the settlement of tank foundations by the analytical method and the finite element method are presented. The obtained values of vertical displacements were compared with the results of geodesic measurements of the constructed reservoirs. The analysis of the results obtained showed good convergence of the calculation results by the analytical method with the actual measurements of the vertical displacements of the foundations. Also, the economic efficiency of using a foundation on a reinforced base was determined.

In the presented article, the authors consider the issues of quality control of bored piles in the practice of bridge construction. The importance of quality control of these pile structures is emphasized. The basic requirements for quality control in the production of construction works and their acceptance are presented. A description of the control method is given. As a practical example, the results of quality control of the execution of bored piles by the method of cross well ultrasonic scanning at the bridge over the river Chusovaya. An assessment of the state of bored piles after testing is given.

In the case of thick soft and unstructured soils, pit excavation causes 20-75% of pile heads to have higher-than-normal horizontal displacements. The paper presents the results of statistical analysis for 9865 piles installed in pile fields at 17 construction sites in St. Petersburg, Perm, and Volgograd. We note that the distribution of frequencies of horizontal pile displacements follows a normal law. During the analysis, we identified the main factors affecting pile displacement: the time when a pile is in the slope, the properties of the cut soils, their tendency to softening, the excavation scheme, and the availability of pile head anchorage. The paper justifies the effectiveness of pit excavation in work zones of up to two meters deep with changes in the direction of machinery movement. We provide recommendations for raft design and analysis with account for possible displacement of pile heads.

Annotation. A method for calculating the settlement of ring pile foundations of reservoirs on clay soils is considered. The proposed method provides for a separate calculation of the settlement of the central part of the tank (bottom draft) and a reinforced concrete ring pile foundation arranged along its edges (foundation ring settlement). The bottom of the tank is not rigidly connected to the ring foundation. The method of M I Gorbunov-Posadov and others for a flexible round foundation on a linearly deformable base was used. When calculating the settlement of the pile ring, the method of A A Bartolomey was used for strip pile foundations. The work takes into account the assessment of the additional settlement of the bottom and pile ring caused by repeated loading and unloading of the base of the tanks.

The article describes the experience of designing and construction the Olympic facilities in Sochi-2014 in difficult engineering and geological conditions, including on weak clay soils, with a seismicity of 9 points. Specific examples of design solutions and their implementation are given, as well as geotechnical monitoring data.

The research addresses the issue mathematical modeling of effective pile for construction in cold regions on the base of existing experimental studies. The problem of piles uplift by frost heave is critical and results in damage to overlying structures. Previous research and practice has shown that the existing methods of frost heave protection involving pile length extension lead to piles cost increase. It is assumed that a novel approach to the piles design is needed. The paper proposes directional reducing the influence of heaving soil on the reverse taper pile due to pile design features without its length extension. Positive effects which arise in this connection have been studied. The devised approach was based on mathematical modeling techniques. Heaving soil-pile interaction model has been developed. The study conducts an investigation of the pile frost heaving phenomenon that occurs in the annular space surrounding the pile. Particular attention has been given to working out pile geometry equations. It is concluded that the pile geometrical features developed by the devised mathematical modeling techniques allow to effectively reducing the frost heave influence. We can foresee that the research findings and the approach implementation will entail the reduction of construction costs in cold environments.

The permafrost zone is one of the main natural systems in the Russian Federation that are exposed to global warming. The temperature of permafrost soils changes, the seasonal thaw zone increases, the process of permafrost degradation is started, influencing the strength properties of the soils. The study sought to assess climate change in terms of the impact on the bearing capacity of the soil under buildings and structures built in the 1960s and 1980s on the principle of maintaining the permafrost condition of soils. On the basis of published archival and forecast data on the increase rate in the active layer thickness and the rising trends in the temperature of permafrost soils for four geographical regions of Russia (North of the European part, North of Western Siberia, Middle Siberia, Yakutia) a reduction in the bearing capacity of the standard reinforced concrete pile was determined (35x35 cm section, 10 m long). The study showed that, for most regions, the reduction in the bearing capacity of the pile is currently on average level (10-20 %). However a high (>30%) decrease is expected by 2050.

Freezing of wet dispersed soils is accompanied by a number of physical, physicochemical and physicomechanical phenomena and processes. In soils, when water freezes, the properties of the soils themselves change abruptly and abruptly, and the volume of frozen soil increases significantly, and not evenly. It was revealed that during freezing conditions can arise under which an increase in soil volume due to moisture migration to the freezing front and its freezing can reach tens of percent. This process is usually called frost heaving of soils. This phenomenon refers to physical and mechanical processes, as a result of which, under the influence of thermodynamic changes, the freezing soil acquires a stress-strain state. To combat frost heaving, it is necessary to study the patterns of changes in the water-thermal regime of road structures. The article presents various methods for assessing the water-thermal regime of road structures. The developed system of temperature monitoring of the road structure to a depth of up to 3 m and some measurement results are described, which make it possible to assess the temperature change at different depths from the road surface.

Due to the intensive development of the underground space of Moscow and the increasing requirements for environmental protection, there is a need for continuous high-precision monitoring of the settlements of existing structures of normal and higher levels of responsibility. Moreover, if points of observation of the structure are located in an open space, then traditional geodetic methods (using optical levels, tacheometers) cannot ensure the continuity of observations (for example, in case of heavy rain, fog, snowfall or smoke). This, in turn, does not allow us to promptly respond to emergencies and take measures to prevent them. The article discusses the experience of automated real-time monitoring using Monitron hydrostatic leveling system to prevent an emergency during the construction of a collector tunnel with a diameter of 4.0 m under one of the Moscow Metro lines.

Sheet piles are often used for fencing deep excavations. This is due, among other things, to the fact that when they are pressed, there is no negative impact on the surrounding buildings. In the course of the study, a technical and economic comparison of the domestic sheet pile L4 and its foreign analogue VL603K was carried out. The relevance of the study is confirmed by the fact that during the construction of underground parts of buildings and structures, great attention is paid to engineering measures to prevent the ingress of groundwater into the pits, as well as to strengthen the walls of the excavations from the possibility of collapse in unstable and water-bearing soils. It is also taken into account that the choice of the foundation pit construction depends on its depth, the level of groundwater and the structural scheme of the underground part of the structure, it is also necessary to carry out a static calculation to determine the thickness of the fence and its immersion depth. The analysis of sheet piles also revealed their disadvantages and advantages.

When designing the foundation slab for a building facility, engineers decided to partially replace the base soils with a sand cushion having a deformation modulus of 18-25 MPa. This paper presents the results of quality control of fill soils compaction during the cushion construction. The compaction factor and the compression modulus of deformation were determined for each layer of the sand pad. There were also three stamp tests carried out on its surface. At the same time, several of additional studies were performed to control the quality of sand cushion compaction using express methods: the determination of the dynamic modulus of soil elasticity using the dynamic density meters DPG 1.2 and Terratest 5000 BLU; the determination of the sand cushion homogeneity by the CMPW geophysical method (the correlation method of refracted waves). The test results were presented, and a conclusion was made.

The paper is devoted to researching into the behaviour of reinforced pads made from cohesive soil. Compacted soft-plastic loam was considered as a pad material, and woven geotextile was used as an reinforcing element. The research was aimed at testing a well-known approach to the usage of a variable reinforcement pitch in cohesive soil pads. The goal was achieved by solving test problems for various types of reinforcement in the Plaxis 2D software package. Based on the results of the research, the formula for determining the arrangement of reinforcing layers at a variable reinforcement pitch in cohesive soil pads was adjusted. It was also found that when the layers were arranged at a pitch of 200 mm or less, the reinforcing effect in cohesive soils practically did not occur. In addition, it was confirmed that at a variable pitch of reinforcement, there was the most complete "inclusion of geosynthetic materials in work" in comparison with other considered cases of reinforcement.

The article provides information about the advantages of using information modeling technologies in the design and construction of facilities for subsoil use enterprises. The data on the state of the art of studying the aspects of the application of information modeling technologies in the field of industrial construction are presented. Recommendations for planning methods and the development of information models of buildings and structures of subsoil use objects are presented on base of the study of existing research. The article also provides information on the test information models of subsoil use industrial facilities which are necessary for the development of recommendations for the choice of levels of the attribute information of elements, for the correct and effective use of models at all stages of the object's life cycle.

As biodegradation proceeds, municipal solid wastes (MSW) acquire pronounced soil-like properties and upon completion of the process can be used as the foundation. The solid waste massif is an inhomogeneous soil-like mass which requires non-destructive and minimally invasive methods of research. The cone penetration testing of MSW by piezocone (CPTU) in combination with the multichannel analysis of surface waves (MASW) provide extensive data about physico-mechanical properties of wastes, which are usually unavailable in traditional approaches and which can be directly used in geotechnical stability calculations of the waste massif.

The paper presents the numerical simulation results of reinforced sand pads under load. During the simulation, the parameters of the soil base, the pad material, as well as the reinforcing materials varied. Based on the results of the study, a formula for determining the ultimate resistance force of a reinforced sand pad was set.

Pile foundations are among the most common types of deep foundations. Predicting their draft is a fairly standard engineering goal. There are many techniques for this. Many methods for determining the settlement of piles are based on various empirical relationships. In particular, the cone penetration test allows you to determine the settlement and bearing capacity of a pile using the developed empirical dependencies. However, some models must be used to develop such correlations. This study proposes to use a slightly different approach. Instead of using a pile model and a set of empirical dependencies, it is suggested to use machine learning methods. Artificial neural networks are one of the machine learning methods. The article presents a description of the development of a neural network that allows estimating pile settlement using data from the CPT test.

The authors propose a new approach to the settlement calculation of a single widened pile in a punched hole beyond the linear dependence between stresses and deformations in soil.

The construction and operation of bridge foundations in permafrost conditions is associated with many problems, the most urgent of which is the degradation of the frozen state of soils due to the effect of solar radiation on the thawing process. Thawing of permafrost soils of the base significantly affects structures, the design of which does not provide for thorough protection from natural factors - first of all, these are railway bridges. The changing climate has a destructive effect on permafrost soils, which is destructive for infrastructure facilities operated in the permafrost zone. The aim of the given work is to increase the efficiency of systems that regulate the temperature regime of permafrost soils of the bridges foundations which are located on railways in permafrost regions.

It is necessary to assess the additional loads transferred to the piles during the growth of a karst cavity in karst soils for designing bridge support pile foundations in karst areas. Additional loads arise due to the displacement of the soil mass above the cavity and the emergence of "negative friction" forces on the pile lateral surface. The paper proposes a method for determining the additional load on the pile depending on the distance from the pile bottom to the karst soil roof and the predicted diameter of the cavity in karst soils. A method for numerical variation calculations based on the analysis of the change of shear stresses on the pile lateral surface at different stages of loading with the growth of a cavity and the stable arch over the cavity is proposed. The correct design model and criteria for stability evaluation of the arch over the cavity are selected. A series of numerical calculations are made. An analytical solution to determine the additional load on the pile depending on the distance from the pile bottom to the karst soil roof and the predicted diameter of the cavity in karst soils is obtained.

The paper presents the study results of the stress state at the contour points of an underground horizontal working carried out by the methods of the complex variable theory. This study is the basis for solving the problem of determining an allowable value of the uniform pressure transmitted to the contour of the working, with predetermined values of the depth of its laying. The condition proposed by the authors of the paper is used as a criterion of strength (stability), according to which the working's contour strength is ensured if at any point the amount of the tangential normal stress does not exceed the tensile and compressive strength of the host soil (rock), i.e. σ_t ≤ σ_e ≤ σ_c. As a result of the solution, an assessment of the stress distribution on the contour of an underground horizontal working has been made. The working has a cross-section in the form of a curved trapezoid, which is under the action of uniform all-round stretching of a given intensity with a varying depth and various values of the host mass lateral expansion coefficient. The allowable values of the tensile internal pressure on the contour of an underground horizontal working of a trapezoidal cross-section have been determined at the given values of its depth and a constant coefficient value of the lateral expansion of the host mass μ = 0.25. The materials presented in the paper can be used when choosing the maximum or minimum allowable depth of the working used as a storage facility for liquid or gaseous hydrocarbons.

The article describes design of a pile with new rotary anchors for foundations of buildings operating on variable loads or on heaving soils. The results of plate load tests on piles' pressing in with one- and two anchor levels are presented. Based on calculations on bearing capacity of piles of proposed design, the adequacy of data on determination of its bearing capacity obtained by experimental method is calculated. Bearing capacity of anchor piles for pulling out is determined by calculations. Anchors located at one level at the height of pile increase its bearing capacity for pressing in by 20%, and increase it for pulling out by 94%. Anchors located at two levels at the height of pile increase bearing capacity of pile for pressing in by 60%, and increase bearing capacity for pulling out by three times. A decrease in the settlement of pile of proposed design is determined by the results of plate load tests on pressing in and it amounts to 85% for a pile with one-level anchors and to 94% for a pile with two-level anchors.

The results of experimental and theoretical studies of vertically loaded large-size (from 50 and more meters long) bored pile work features are presented. The results of testing the vertically loaded large-size bored piles with a diameter of 2m, a length of 55m and 65m in clay soils by the submerged jack method are analyzed. According to the test results, the features of the soil resistance formation under the pile tip and on the side surface are identified. On this basis, the need to design such piles according to the second soil limit state, taking into account the compressibility of the pile shaft is justified. The kinematic scheme of inclusion the soil base and the pile shaft into work under vertical loading is given. On this basis, a technique for calculating the settlement of a single pile and a method for determining the allowable load on the pile are developed. This load does not allow pile settlement to exceed the allowable settlement of the designed building. An example of a bored pile calculation by the developed method is given.

The results of experimental and theoretical research in work features of a rammed pyramidal pile with compacted bottom for horizontal load in clayey soils are presented. The experimental cast-in situ pyramidal piles with compacted bottom were made at 2 experimental sites, composed of clayey soils. Static horizontal load tests were carried out. At each stage of loading, horizontal displacements were measured at the load application level and at a height of one meter from the top edge of the pile. The "horizontal load - pile head displacement" dependencies were obtained. It was found that the rotation of the pile in the soil occurs without bending, i.e. according to a rigid scheme, and also that compacted bottom prevents horizontal displacement of the pile bottom. Based on the analysis of the results of static tests of piles, a design scheme has been created, in which the pile is considered as a rigid rod buried in a multilayer linearly deformable base with a point of zero displacements at the lower end of the pile. In accordance with the design scheme, an analytical method for calculating a pyramidal pile with compacted bottom for horizontal load and bending moment has been developed. The calculation method allows to determine the horizontal displacement of the pile head in any section along the depth, the angle of rotation of the pile, bending moment and shear force along the length of the pile.

The article provides the information about studies devoted to determining the position, shape and size of the elastic soil core and areas of plastic deformations formed in the soil foundation under the jucked stamp. Based on the results analysis of experiments carried out by third-party researchers and the results of calculations performed by the authors of the article, it was concluded that an elastic soil core in the form of a triangle is formed in the case when the indentation of a stamp is carried out into a base folded with loose ground, provided that φ>25-30° (this depends on the value of the lateral soil pressure coefficient), and the specific cohesion C is quite small. In cohesive soils, the vertical section of the elastic soil core has a form close to that of half an ellipse, half or a segment of a circle. The exceptions are the results of the experiments by Kaganovskaya S E, where a triangular elastic core was obtained for clay soil. All these facts are in satisfactory agreement with Prandtl's design scheme, and therefore, the use of calculation methods based on it is justified only for sandy bases. To solve the problem of calculating the bearing capacity of soil foundations composed of various types of soils, methods should be created that are not based on hypotheses about the shape of the elastic core and areas of plastic deformation.

The information on the basics of designing pile foundations on swelling clay soils is presented and analyzed. New designs of conical piles and those with a variable cross-section, in which the soil mass swelling is accompanied by the effect of pile pinching, have been developed. Moreover, new pile foundation structures with protective shells involving a calcium elastic rolling member and some rubbing elements like low-friction plastic and metal braces are proposed.

The analysis of the results of the experimental researches conducted in Platov South-Russian State Polytechnic University (Novocherkassk Polytechnic Institute), in conditions of tape and axisymmetrical basis loadings permits to identify general patterns of the sand basis operating in case of different loading conditions, to consistently trace the development of ranges of strains, compaction and decompaction and the formation of a condenced core under stamps and to assess this process with the phases of the stress - strain state of the basis.

The results of laboratory studies of strength and water resistance indicators of asphalt treated with different amounts of added foamed bitumen by using cylindrical specimens for indirect tensile strength test are presented. It has been experimentally established that the fulfillment of the minimum requirements for material of class 1 is observed with the addition of foamed bitumen of at least 2.2%.

The article presents the test results of clay reinforced with discrete polypropylene fibers. The authors prove the effectiveness of fiber reinforcement to improve the soil's strength characteristics and the lack of fibers' effectiveness to increase the deformation characteristics. The article presents previous studies on the effect of fiber reinforcement on the degree of swelling and shrinkage of the soil. The testing program and results of heaving tests are considered. The article presents an analysis of the influence of fiber reinforcement on the soil's heaving properties on the thawing coefficient and compressibility of clay soils during thawing. The test results are presented in tables and graphs, conclusions and recommendations are drawn up.

The paper notes that the influence on the increase in the clay soil swelling disturbs both intra-aggregate and inter-aggregate bonds. A new technique and device for studying the "sensitivity" of swollen clay soils have been developed, which make it possible to study more accurately the swelling of clay soils in the natural state and also in the structurally disturbed one on the same sample. Studies of the swollen clay soils "sensitivity" selected from various regions of Azerbaijan have shown that with an increase in the depth of clay soils, their coefficient of structural strength influence on swelling, i.e., "sensitivity" increases significantly.

The article describes the reconstruction of the historical stone building basements. It provides a brief description of the constructive solution of the buildings under consideration and summarizes information about their technical condition. The article highlights the importance of analyzing information about the construction and operation of buildings during the entire history. This article lists the main tasks of the reconstruction of historical buildings: area augmentation due to the reconstruction of previously unexploited basements, deepening of basements, expansion of existing openings in the walls and construction of new ones, arrangement of new entrance nodes into the basements of a building, etc. Besides, the article gives a brief description of the soil conditions of the reconstructed buildings sites, which are typical for historical buildings in Tomsk. It points out the need for thorough engineering and geological examinations with additional geotechnical examination of the soil base. Additionally, the paper clarifies the necessity to examine the characteristics of supporting layer foundation soils, changed due to their compaction by the weight of the building during the period of long-term operation. The results obtained during the examination and assessment of the technical condition of foundations and overhead building structures will be presented. Also, this study proposes classification of methods for strengthening natural foundations (freestanding, strip, slab and massive) using piles. In particular, it talks about piles that are installed without soil extraction - displacement piles (pressed and injected), as well as examples of numerical modeling of the work of detached and strip foundations reinforced with the use of piles when the basement floor elevations are lowered. Finally, it shows he experience of scientific and technical support for the reconstruction of buildings.