Инновационные процессы в исследовательской и образовательной деятел

where T is time determined on the basis of the design calculations, day; temperature, K; x, r are the distances from the source of cold, m; t0 temperature of the cold source, K; t1 is environment temperature, K.

Also, with the application package ANSYS there was created a simplified mathematical model of the rock mass (Fig. 1) divided into three characteristic layers, different in their thermal properties.

Fig. 1. A spatial model of layered rock massif: 1 – temperature field;

2 – freezing wells; 3 – massif’s strata

Thermal properties of soil strata on the rock massif

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Due to the fact that the rock massif is heterogeneous, the drilling of wells is not rectilinear, so inclinometric data of wells were used to create geometrically accurate models. This data were obtained from the research facility and processed in geoinformation system ArcGIS, by which the thermophysical data from the massif were also received.

As a result of the use of experimental data during modeling the time length was received for freezing soil to 6 m thickness with a source of cold (Fig. 2.) placed in the center of the frozen rock wall. The time required for freezing to a temperature of 0 °C equals 105 days for model (2) and 170 days for model (3). The use of computational modeling package application ANSYS allowed getting the value of soil freezing time of 200 days.

Fig. 2. Temperature change from time dependence for the distance of 3 m from freezing wells: for models of one-dimensional transient heat conduction of a halfclosed flat massif – 1; half-closed cylindrical wall – 2; a two-dimensional finite element model – 3; and for design calculations – 4

Analyzing the data, it can be assumed that the improvement of the design model leads to the indicators close to the design. But the difference between the results of calculations, which is equal to 60 days, is large enough to rely on design calculations, as well as the mathematical modeling.

In the future, it is planned to examine the structure of the rock mass in detail, its thermal and mechanical properties, speed and temperature of water inflows to more accurately determine the formation time of frozen rock massif of required thickness. Due to the fact that the rock massif is a complex composite material, it is planned to improve the calculation model which will take into account both a complex distribution of temperature and its impact on stress strain behavior of rocks, the reliability and durability of the lining [4], and formation and development of cracks [5], using the methods and approaches of the mechanics of composite materials.

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References

1.Константинова С.А., Хронусов В.В. Проявление горного давления вокруг подземных выработок в калийных рудниках в случае негидростатического начального напряженного состояния // Физико-технические проблемы разработки полезных ископаемых. – 1999. – № 22. – С. 25–34.

2.Болотских Н.С., Бондаренко Н.А., Гальченко П.П. Строительство

3.Булычев Н.С., Комаров Д.С., Лукашин С.Б. Расчет необходимых параметров ледопородного ограждения // Известия ТулГУ. Естественные науки. – 2012. – Вып. 1, Ч. 2. – С. 54–60.

4.Sokolkin Yu.V., Postnykh A.M., Chekalkin A.A. A probably model of strength, fracture toughness and fatigue life of unidirectionally reinforced fibrous composites // Mechanics of composite materials. – 1992. – Vol. 4, № 2. – P. 196– 203.

5.Расчет эффективной трещиностойкости для упругопластической слоистой среды / Р.Я. Газизов, С.Л. Калюлин, Р.Н. Сулейманов [и др.] // Вестник Пермского национального исследовательского политехнического университета. Аэрокосмическая техника. – 2014. – № 37. – С. 154–171.

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D.A. Tatiannikov, V.I. Kleveko

Perm National Research Polytechnic University

STUDY OF GEOSYNTHETICS INTERACTION CHARACTERISTICS FOR RESEARCH OF REINFORCED FOUNDATION

PAD BEARING CAPACITY

The paper considers the results of shear and pull-out tests carried out to determine friction coefficients and pull-out resistance for two types of geosynthetics. The influence of geosynthetics-soil interaction on reinforced foundation pad bearing capacity is studied.

Key words: shear, friction coefficient, pull-out resistance, reinforced foundation pad, geosynthetics.

The use of soil pads is the most simple and rational technology existing nowadays for laying foundations in soft soils. The main disadvantages of this method are: relatively high materials consumption, large volumes of earthwork, as well as imperfection of current computing methods often giving exaggerated characteristics. The use of reinforcement in similar constructions makes it possible to reduce financial costs to a significant extent.

According to [1], the mechanical properties of reinforcing materials (geosynthetics) have a great influence on the bearing capacity of reinforced foundation pads. There are a lot of papers devoted to the study of such characteristics as rupture strength and specific elongation, whereas the influence of geosynthetics – soil interaction characteristics on the reinforced foundation pad bearing capacity has not been investigated in our country yet.

It is possible to evaluate this interaction by doing the geosynthetics shear and pull-out tests [2, 3].

All experiments were carried out on the basis of the building faculty of Magdeburg-Stendal Hochschule (Germany). A special shear system made in accordance with the requirements of DIN EN ISO 12957-1 and DIN 60009 was used as the experimental equipment.

Two types of geosynthetics – the Secugrid (NAUE GmbH & Co) geogrid and the Geospan (Hexa) woven geotextiles – were used in the shear and pull-out tests.

Shear and pull-out testing technique was adopted in accordance with the German normative documents, DIN EN ISO 12957-1 and DIN 600009.

For example, the friction coefficient introduced to evaluate the geosynthe- tics-soil interaction more accurately in shear tests was determined according to DIN EN ISO 12957-1, paragraph 9. It is impossible to assess the bearing capacity of foundation pads on reinforced soils without this coefficient [4]. The obtained values of the friction coefficient are given in Table 1.

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T a b l e 1

Values of friction coefficients

The main parameter of the geosynthetics-soil interaction when doing the pull-out tests was the maximum value of pull-out resistance, which was determined in accordance with paragraph 8 of DIN 60009. That parameter made it possible to evaluate the stability, shear strength of constructions, as well as the ability of reinforced soil to expand [5, 6]. The obtained values of pull-out resistance are summarized in Table 2.

T a b l e 2 Values of pull-out resistance for different types of systems

Conclusions

1.The analysis of the experimental dependences showed that the ‘sand- sand’ system was able to perceive larger shear stresses (164.8 kPa) than the

‘sand-geogrid’ (152.7 kPa) and ‘sand-geotextile’ (138.5 kPa) systems.

2.In the constructions, that perceive significant shear forces, the use of geogrids is more reasonable than the use of geotextiles. This conclusion is confirmed by the obtained friction coefficients.

3.The value of the friction coefficient goes up when the normal stress increases to the peak value. Then it goes down for both types of geosynthetics system (see, Table 1). This dependence must be taken into account in the calculation of the reinforced foundation pad bearing capacity.

4.The lack of shear and pull-out test data understates the value of the reinforced foundation pad bearing capacity, which leads to the construction errors even at the design stage.

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References

1.Пономарев А.Б., Татьянников Д.А., Клевеко В.И. Определение линейной жесткости геосинтетических материалов [Электронный ресурс] // Интернет-вестник ВолгГАСУ. Сер.: Политематическая. – 2013. – Вып.

2(27). – URL: http://vestnik.vgasu.ru/attachments/PonomarevTatyannikov Kleveko2013_2(27).pdf (дата обращения: 18.02.2015).

2.Определение характеристик трения для двух типов геосинтетических материалов путем проведения испытаний на сдвиг / Д.А. Татьянников, А.Б. Пономарев, В.И. Клевеко, S.H. Schlömp, S. Schwerdt // Вестник Пермского национального исследовательского политехнического университета. Строительство и архитектура. – 2014. – № 1. – С. 174–186.

3.Татьянников Д.А., Клевеко В.И. Определение характеристик взаимодействия геосинтетических материалов с грунтом // Модернизация и научные исследования в транспортном комплексе. – 2014. – Т. 1. – С. 526– 529.

4.Alfaro M.C., Miura N., Bergado D.T. Soil geogrid reinforcement interaction by pullout and direct shear tests // Geotechnical Testing Journal, GTJODJ. – 1995. – Vol. 18, no. 2. – P. 157–167.

5.Koerner R.M. Designing with geosynthetics. – New Jersey: Upper Saddle River, 1999.

6.Melo D.L.A., Santos E.C.G. Shear strength of RCDW/nonwonen geotextile interface // 10th International Conference on Geosynthetics – Berlin, 2014. – Vol. 7.

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S.Y. Khovaev

National Research University Higher School of Economics

CREATION OF INNOVATIVE PROJECT MANAGEMENT SYSTEM

This paper examines the possibility of using the current project management system for projects with a high level of complexity and uncertainty. Based on a literature review in this area a new project management system has developed. This system combines the most essential elements of project management in order to manage complex projects.

Key words: project management, innovative projects, system of project management.

Nowadays, the organizations operating in the dynamic environment have to constantly innovate to maintain the market share. The use of obsolete management techniques is not sufficient to provide growth. Innovations have become an essential part of any organization activities. Innovations can be implemented by using of project management.

The role of project management increases in the science of management. Using project management an organization becomes more flexible and easily adaptable to environmental changes. Although the project management was developed more than 50 years, the current project management manuals are designed for standard projects with low uncertainty level. Innovative projects are characterized by high level of uncertainty and project complexity [1].

Projects can be divided into four categories according to the complexity and the environment uncertainty level. The three types of projects (ad-hoc, bureaucratic, normative) are described in the current works of project management. The fourth type of projects (innovative projects) characterized by high levels of complexity and uncertainty, is not studied in detail. To manage innovative projects we need to create a new system adapted to the complexity and uncertainty of the specific environment [1]. This system should include five main elements:

1.Strategic project management, when organization should use projects to achieve its objectives, as a result projects are related to organizational strategy. The projects, which are not connected with the organizational strategy, are considered to be a waste of corporate resources [2].

2.Key success factors. There are many empirical studies aimed at identifying the factors that determine the project success (management, good communications, clear objectives, detailed plan, sufficient resource etc.). These factors create the basis for the successful project management. Without these factors the probability of good result declines [3].

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3.Context project management. The project management team should take into account the environmental factors, such as clients, suppliers, rivals, partners, government and other stakeholders. Each project should be considered with relevance to its environment. It is obligatory to do before the project is launched.

4.Risk management. Nowadays there exist different methods to measure the risk of the project as well as the methods that allow us to decrease risk. Managers should select projects according to their risk level. The more risky projects are more suitable for organization with high margins that decrease the possible negative result of risky projects. If company does not have sufficient resources to launch a risky project it should use special techniques to decrease the probable risk or abandon the project.

5.Project evaluation. Traditional quantitative methods of project evaluation are suitable for standard projects, but when it comes to innovative projects it is necessary to complement quantitative methods with qualitative ones. Qualitative evaluation methods allow us to understand the role of this project for organizational strategy, the leadership competences of the project manager, the links existing between the project and the organization environment. Thus, qualitative methods allow us to take into account not only financial factors [4].

All these factors could be combined within the integrated system (Figure). This system consists of three main elements: organizational context, environmental context and internal factors of projects.

Fig. System of innovative project management

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B.S. Yushkov, O.V. Tretyakova, S.A. Rebrov

Perm National Research Polytechnic University

APPLICATION OF SHEET-PILE WALLS

IN SOIL FROST HEAVING ENVIRONMENT

The stress-strain state of inclined piles of thin sheet-pile walls without anchors and with anchors in soil frost heaving environment is considered. An analytical and design comparison of pile design options is carried out. The conclusion about the ways of sheet-pile walls optimization in heaving soils is drawn.

Key words: soil freezing, frost heaving force, sheet piling, anchors, biconical piles.

The development of trench and retaining walls fastening in different soil conditions, including soil frost heaving, has become an urgent problem in the conditions of dense urban development and the growing rate of hydraulic and transport construction. The solution of this problem is connected with the study of soil properties at freezing and the rational design of retaining walls.

Frozen water can be an element of permafrost or it can be of seasonal freezing nature, depending on a climatic region. Freezing of wet dispersed soils is characterized by a number of physical, chemical and mechanical laws, the main of which is the redistribution of humidity and moisture migration in frozen soils.

Moisture and water migration in frozen soils gives rise to their volume gain. When water contained in the soil or entering it as a result of migration is frozen, the soil properties change unevenly due to the increase of adhesion forces. The uniform increase in soil volume over a large area does not cause internal stresses, but the natural heterogeneity of soil and the impact of buildings and structures on it cause uneven and local character of the soil volume increase. According to N.A. Tsitovich [1] this is the very cause of significant frost heaving forces.

M.F. Kiselyov [2] also notes the impact of water crystallization on frost heaving when water is additionally pulled to ice crystals. Normal and tangential forces of soil frost heaving cause deformations of above-ground and underground parts of buildings and engineering structures.

Anti-heaving measures to protect buildings and structures are directed at avoidance or restriction of deformations produced by frost heave forces. These measures are carried out on the basis of engineering and land reclamation, thermal, chemical, and structural solutions. They can be temporarily taken in the course of construction.

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