## Vol 9, No 1 (2018)

NUMERICAL MODELING OF PILE FOUNDATIONS USING SCAD OFFICE STRUCTURAL ANALYSIS SOFTWARE
Nuzhdin L.V., Mikhaylov V.S.

#### Abstract

The article gives a comprehensive review of the main methods aimed at creating analytical and numerical models of slab-pile foundations in accordance with the present technical requirements using SCAD Office structural analysis software. Based on the example of a pile-and-slab foundation analysis, the authors compare the results which have been gained using analytical and numerical methods for two types of foundations, one of them has yield and the other one has rigid piling. Both foundations are ruggedized by basement walls. In order to determine the optimal analysis method for pile-and-slab foundation, three analytic methods of piling modeling are considered in accordance with SNiP 2.02.03-85 and SP 24.13330.2011. Besides, the authors have demonstrated the use of two numerical methods which are based only on the finite elements method for linear-elastic tasks solved using the widespread application sofware. The analytical modeling, which is regulated by standards, is carried out using the mathematical package SMath Studio. It is supposed that the complete analysis technology will use a standard mathematical package for import and export to and from the common data interchange format (DIF) in a structured view, which is acceptable for import and export in the SCAD system. A detailed description of the calculation technology is presented by the authors, thus indicating the applicability limits of these methods and recommendations for their use in static conditions. The demonstrated example testifies a fine precision of the considered methods. The research could be of great interest for designing engineers, university postgraduates and undergraduates.
Construction and Geotechnics. 2018;9(1):5-18
STUDYING THE INTERACTION OF PILES AND GRILLAGE MODELS
Mets M., Leppik V., Needo R.

#### Abstract

This paper investigates the interaction of grillage and piles with pile models. Steel pipes and concrete wedged piles were used. The tests were performed in a 3500×2000×2500 concrete box with medium-grained sand. The metal piles were 620 mm tubes with a diameter of 33.1 mm. The grillage was a metal plate 400×400×20 in size. The other series of tests was carried out with concrete wedge piles that were 300 and 400 mm in length and with metal grillage. The tests were made with a high grillage, when only the piles were performing; and the tests were made with a low grillage, when the function was divided between the piles and the grillage. The high grillage tests indicated that the shaft resistance and creep point do not depend on the number of piles in the foundation, but it does affect the ultimate load of the piles. The tests with a low grillage show that piles function as the primary load bearers up till their ultimate capacity, from which point the grillage switches into the combination. If the number of piles under the grillage is 4.5 and 9, the creep point and ultimate pressure on the pile foundations will rise with the number of piles used. The tests with wedge piles showed that in driving and loading wedge piles, the soil gets pressed out. The load bearing capacity of wedge piles grows with the rise in pile size and the density. The tests carried out using the combination of grillage and piles showed that the piles function as the primary load bearers up till their ultimate capacity is reached. It is only then that the grillage starts to work. The bearing capacity of the pile foundation consists of the sum of the ultimate load bearing capacity of the piles plus the bearing capacity of the grillage. The study shows that the idea of considering the interaction between piles and grillage allows us to reduce the number of piles used in pile foundations, as well as the cost of pile foundations in the future.
Construction and Geotechnics. 2018;9(1):19-29
NUMERICAL AND MODEL EXPERIMENTS TO DETERMINE THE STABILITY OF A HOMOGENEOUS SLOPE UNDERMINED WITH A HORIZONTAL PRODUCTION
Bogomolov A.N., Abramov G.A., Bogomolova O.A., Pristanskov A.A., Ermakov O.V.

#### Abstract

The article presents the results of the numerical analysis and model experiments to study the stability of a homogeneous isotropic slope undermined with a horizontal production having a cross-section in the form of a circle. Flume experiments were carried out on the models of homogeneous slopes, formed of an equivalent material, i.e. sand-oil mixture, physical and mechanical properties of which are close to some sandy and cohesive soils. The value of the coefficient of material’s lateral pressure is determined using the method of K.Terzaghi which entails pulling the steel band through its thickness. The models calculation and mathematical processing of the obtained results is made with the help of the software which is registered in the State Register of Computer Programs and Databases. The software formalizes the finite element method, the analytical solution of the first main and the basic mixed problem of the elasticity theory and an approximate analytical solution of the mixed problem of the theory of elasticity and theory of plasticity of soil. The construction of the most probable slip surface is carried out under the condition of the minimality of the numerical values related to the coefficient of stability margin at each point. The analysis of the results gained form the model and numerical experiments has shown their satisfactory convergence. As a result of the numerical experiment it is established that there is a significant concentration of the stress field and occurrence of regions of plastic deformations at certain distances in the neighborhood between the development and the base of the slope.
Construction and Geotechnics. 2018;9(1):30-41
METHODS OF STRENGTHENING FOUNDATIONS AND basement CONSTRUCTIONS OF RECONSTRUCTED BUILDINGS
Polishchyk A.I., Petukhov A.A.

#### Abstract

The experience of reconstructing and restoring basements of historical stone buildings is given using Tomsk as an example. The article outlines the importance of analyzing information related to construction and operation of buildings throughout their life cycle. The main objectives arising during the reconstruction and restoration of historic buildings are formulated, such as the extension of space due to reorganization of previously unexploited cellars, the deepening of basements, the expansion of existing and construction of new openings in the walls of buildings, the construction of new entry points in the cellars, etc. A brief description of the ground conditions of sites for buildings under consideration which belong to the historical ones. It is noted that it is necessary to carry out thorough engineering and geological surveys including geotechnical surveying of soil grounds and hydrogeological observations revealing the appearance of groundwater. It is proved that it is necessary to identify ground characteristics of bearing layer’s foundations which have been changed due to their compaction by the weight of buildings for a period of long operation. Generalized results obtained during the survey and assessment of the technical condition of foundations, as well as of above-ground building structures are given in the article. A classification of methods is proposed aiming to reinforce foundations on a natural basement (separately standing, band, plate and massive ones) using piles. Also we have considered piles that are arranged without excavation, i.e. piles of displacement (pressed and injected). Examples of numerical modeling are given ragarding the operation of separately standing and band-like foundations which are reinforced with the use of piles, when the basement floor’s marks are decreased. When simulating piles’ work using Midas GTS NX software complex, the successive technological stages of pile assembly are used; which allows taking into account the change in the stress-strain state of the base soil.
Construction and Geotechnics. 2018;9(1):42-51
ABOUT PECULIARITIES OF CALCULATING THE BEARING CAPACITY OF SOCKETED SHAFTS IN ROCK UNDER VERTICAL LOAD
Zertsalov M.G., Znamenskiy V.V., Khokhlov I.N.

#### Abstract

Large diameter socketed shafts are usually used to transfer loads from the aboveground constructions and structures through layers of soft soils to sound bedrock. Often during the construction of bridges and high-rise buildings on soft soils, underling rock formations, socketed shaft foundations are considered to be the most efficient and beneficial deep foundations. In this article the main peculiarities of calculating socketed shafts in rock under the action of vertical loads are analyzed. The major factors affecting the performance of socketed shafts under loads are associated with composition, structure and mechanical properties of rock mass. The main types of interaction of socketed shafts with rock mass under the action of vertical loads, as well as mechanisms of loss of bearing capacity of socketed shafts are described. The article presents the results of numerical simulations in terms of the three-dimensional elasto-plastic problem by considering the performance of the interface between the socketed shaft and the rock mass. Besides, it outlines the method of calculating the drilled shafts in rock under the action of vertical loads which is proposed and developed on their basis. The results are presented in the form of the parametric regression equations and nomograms allowing to perform an ‘express-analysis’ of the socketed shafts, which can be especially useful at the preliminary stage of design of socketed shaft foundations. The authors propose to carry out further studies and generalize domestic and foreign best practices related to socketed shaft foundations, thus improving national studies, as well as to modify the existing regulations, which at present do not contain detail issues of desiging socketed shafts in rock.
Construction and Geotechnics. 2018;9(1):52-59
TO THE QUESTION ABOUT THE ASSESSMENT BEARING CAPACITY DRIVING REINFORCED CONCRETE PILES OF STANDARD CROSS SECTIONS ON HORIZONTAL LOAD
Znamenskiy V.V., Znamenskaya E.P., Chunyuk D.Y., Khaliullina D.R.

#### Abstract

The article is devoted to evaluating the bearing capacity of pre-fabricated reinforced concrete piles with most common serial cross-sections from 0,25х0,25 m to 0,40х0,40 m under horizontal loading. A general classification and a brief description of calculation methods of piles under horizontal loading are outlined here. The issue of choosing a design scheme aimed to calculate the action of the horizontal load on piles using mathematical methods is considered in detail. By calculating pile rigidity based on several most common methods which determine the scheme of its deformation in soil and selection of a calculation method, it has been shown that it is impossibile to consider the specified pile as a hard rod rotating in the soil without bending. To confirm this conclusion, the article presents the experimental results data obtained during the tests under horizontal loading of the pile with a free head in different soil conditions. It has been shown that the considered piles, regardless of soil conditions, lose their bearing capacity because of fracture (in material) under horizontal displacement at the level of soil surface of about 10-15 mm. Based on the analysis of the calculated and experimental data, the article presents a table enabling a preliminary evaluation of bearing capacity for prefabricated reinforced concrete piles having standard cross-sections and a loose head without complex calculations, if the coefficient of proportionality K is known (which are listed in Table B.1, Attachhment В.S.P. 24.13330.2011. Apart from it, the recommendations which help to consider the pinching factor of its head in the grillage and interaction of piles through the soil when evaluating the bearing capacity of piles working as part of the foundation.
Construction and Geotechnics. 2018;9(1):60-69
THE INFLUENCE OF WATER SATURATION OF CLAY SOIL’S BASE ON ADDITIONAL SETTLEMENTS OF A FIVE-STOREY BUILDING WITH A STRIP SHALLOW FOUNDATION
Kudasheva M.I., Kaloshina S.V., Zolotozubov D.G.

#### Abstract

At present, the territory of urban development is becoming increasingly exposed to dangerous geological processes and phenomena. One of such processes is the waterlogging of the foundation soils caused by various factors including leaks from underground utilities. This article considers how underflooding influencs the base soils’s strength and deformation properties when it comes to a five-storey building with brick bearing walls constructed on a strip shallow foundation. The physical characteristics of the soil are given in the article, as well as the results of laboratory tests of clay soil samples with different contents. Strength and deformation characteristics of the clay soil were determined using the compression and single-plane cut methods. After the completion of the tests, the statistical processing of the data was carried out. The obtained regulatory values of the clay soil’s characteristics were compared to the values presented in the regulatory and reference literature. The results of the soil’s laboratory tests were used to simulate the deterioration of the ground base’s characteristics using Plaxis software complex. The calculations were performed in a plain setting using the Mohr-Coulomb model. In the course of numerical modeling, the values of the base soil’s additional settlement of a five-storey brick building were determined for various cases of water saturation. At the same time, the gradual deterioration of the base soil’s characteristics for each of the considered cases was taken into account depending on the area of soil soaking. Based on the results of the numerical simulation, the most unfavorable cases of water saturation of soil foundations were determined.
Construction and Geotechnics. 2018;9(1):70-81
THE INFLUENCE OF HORIZONTAL UNDERGROUND TUNNELS, ORIENTED PARALLEL TO THE FRONT OF THE UNIFORM SLOPE, ON ITS STABILITY
Bogomolov A.N., Abramov G.A., Bogomolova O.A., Pristanskov A.A., Ermakov O.V.

#### Abstract

The paper presents the results of analyzing the numerical modeling of the stress state transformation of a homogeneous slope when it is undermined with horizontal workings having square and circular cross-sections oriented parallel to the slope’ front. The calculations are performed using computer programs which formalize the finite element method to analyze the stress state of the soil massif, provide the solution of the mixed problem of the theory of plasticity and theory of elasticity to build plastic areas (areas of destruction) and the method of constructing the most probable sliding surface which is based on the analysis of the object’s stress state. It is established that the undermining of a homogeneous slope in underground development, in all other equal conditions, leads to a significant redistribution of stresses in a near-slope massif and, as a consequence, changes the position and shape of the most probable sliding surface, as well as the value of the stability factor. The difference between the stability factors among the investigated samples ranges from 13 % to 25 %. The shape and size of the excavation, its location and orientation in the near-slope region, as well as slope’s geometrical parameters, significantly affect the redistribution of stresses in the soil mass. When calculating the stability of undermined slopes it is necessary to check that there are no fracture zones at an excavation’s contour in order to enable its safe operation.
Construction and Geotechnics. 2018;9(1):82-92
NUMERICAL MODELLING OF VIBRATION IMPACT OF MOTOR TRANSPORT ON BASES OF BUILDINGS
Shutova O.A., Ponomaryov A.B.

#### Abstract

The article considers the use of Quake/W module of GeoStudio softaware complex for numerical modeling of vibration influence caused by motor transport moving down the street on bases of buildings and constructions in restrained urban conditions. A module of the software complex is described, its options and parameters necessary for numerical modeling are considered and main attention is paid to selecting the parameters and their values to perform modeling and calculations. The principles aimed at determining the regions of factor space taking into account the considered parameters and their boundary conditions are considered. Soils characteristics of the studied platforms and basic data for modeling have been obtained at natural experimental conditions. The technique enaibling the modeling of a signgle car vibration impact on the base structure is suggested. It proves that when modeling such loadings, it is impossible to draw analogies to seismic influences. In this case loading will have a triangular pulse character, so during the calculation and modeling it is necessary to consider load per axis but not the mass of a vehicle. The results received during the numerical modeling have been presented. Based on the analysis of the obtained data, it has been concluded that there is a nonlinear dependence of the base’s vibration acceleration on the distance to a vibration source. Also the numerical modeling proved that the speedup depends not on the mass of a vehicle, as it has been supposed initially, but on the maximum load on an axis. When comparing the results obtained for various types of soils, it has been established that motor transport exerts the greatest impact on bases consisting of clay soils; the impact is smaller, when bases consist of sandy soils. The data obtained from the numerical modeling are planned to be used further to obtain mathematical dependences of vibration acceleration of buildings’ bases on the studied parameters.
Construction and Geotechnics. 2018;9(1):93-102
FEATURES OF SUBSOIL BEHAVIOR CONSIDERATION IN GEOTECHNICAL DESIGN OF HIGH RISE BUILDINGS LOCATED ON FLOODPLAIN TERRITORIES IN SEISMIC REGIONS
Marinichev M.B.

#### Abstract

The paper contains an example of calculating and designing the foundations for multistoried buildings located on a floodplain of the Kuban River. The construction site of an upcoming residential block is complicated by non-homogenous and spatially irregular sandy-clay layers. In order to determine a foundation type it is necessary to consider such factors as high seismicity and subsoil liquefaction. Foundation design principles have been proposed for the block of multistoried residential buildings located on non-uniformly composed sandy-clay subsoil. Due to a constant development of large cities which is often associated with constructions based on inconvenient geotechnical sites, as well as floodplain areas, the issue of improving the principles of foundation design in such conditions has remained to be relevant for at least two decades. However, any proposed principles of foundation design can be implemented, only if they have the necessary substantiation after all the stages of theoretical, experimental and practical studies. In addition, the number of performed studies and investigated objects should be enough to approve the proposed methods. The research carried out in the last fifteen years allowed the author to generalize the results of scientific and practical work aimed at finding a reliable and rational technical solution for foundations of high-rise buildings located in non-homogenous subsoil conditions. One of these solutions is presented in the paper. The proposed method of foundation design for high-rise buildings on unevenly-compressible soils in seismic regions had been used during the construction process of numerous projects in different cities of Kuban region.
Construction and Geotechnics. 2018;9(1):103-113
AN ACADEMIC MENTOR’S ROLE IN CAREER DEVELOPMENT OF THE POLYTECHNIC UNIVERSITY GRADUATES
Mironov I.P., Belozerova T.A.

#### Abstract

The article reveals an important role of an academic group montor in personal and carrer development of each student throughout the whole tuition period. It examines the dynamics of personal changes that first-year students of the polytechnic university might undergo as a result of their carreer orientation. This work is being successfully carried out in cooperation with the psychological Consultancy Office of the Department of Social and Extracurricular Activities of the University for three years. We have presented the optimized algorithm of the research which allows reducing the timing and increasing the number of career guidance participants. The statistical material clearly underlines the success of both the whole project and its current stage. These studies can help to disseminate positive experience in other universities.
Construction and Geotechnics. 2018;9(1):114-121
ADVANCED TRAININGS FOR POLYTECHNIC UNIVERSITY STAFF IN THE FIELD OF BUILDING ENGINEERING AND TECHNOLOGIES
Chekalkin A.A., Makarova E.Y.

#### Abstract

Additional professional programs for a polytechnic university staff in the field of building engineering and technologies are presented in the article, such as “The implementation of programs using e-education related to building engineering and technologies” and “Development of research and innovation activities in building engineering and technologies”. The Federal State Educational Standard in education and pedagogical sciences (44.06.01 - higher qualification specialists) and the professional standard (01.004 -teacher of professional education, professional education and vocational education) are the basis of these programs. The additional professional programs in the field of building engineering and technologies comprise two academic modules, i.e. state policy in education as the common module and a special module for each additional professional program. The common academic module includes the following main topics: the structure of Russian educational system, the organizational principles of educational activities, the rights and responsibilities of teachers and students, the state planning and regulations of educational activities, the management of the education system, economic fundamentals and financial support, the international cooperation in the educational field. The special academic module on the implementation of the main professional program using e-education includes the following topics: information modeling in construction engineering and technologies, the program package for construction information modeling (CIM), organization of the project file, exploring the interface, assessment of functionality, functional features of CIM, using simulation tools, working with objects, modeling of your own objects, getting information from digital building models (types, specifications, statements, catalogs, etc.), modeling of high buildings, validation of models, cloud technology and mobile access to CIM data, engieneering design documentation, external links, templates and tools of model’s further development. The special academic module related to the development of research and innovation activities includes other topics as well: research activities in the planned and market economies, market relations in research activities’ management, pricing, pricing strategies with setting the price for an innovative product, approach tracking of competitor prices and effective advertising. The staff trainees of the additional professional program defend the final certification work. The individual assignments of the final certification work are the development of methodical guidelines for different disciplines, students’ methodical guidelines on research work, lectures and manuals, textbooks, manuals to laboratory work, manuals to self-study work or the preparation of scientific publications, grant application and innovative project.
Construction and Geotechnics. 2018;9(1):122-136