Construction and Geotechnics

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.

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.

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.

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.

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.

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.