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№4/2015

 

Magazine «Engineering Geology» , 4/2015

 

SOIL’S STUDIES

Korolev V.A., Chzhan Shenzhun

Modeling of sandy soils with specified physical and physical-mechanical properties ...6

The article considers questions of modeling of sandy soils with specified physical and physical-mechanical properties using an original graphic method proposed by the authors, i.e. using triangular diagrams represented by modified Feret triangles. Such triangular diagrams constructed on the basis of experimental investigations make it possible to select mixtures of various granulometric fractions to obtain soils with specified values of their physical and physicalmechanical parameters such as the density, porosity, angle  of internal friction, etc. The offered method can be very useful and efficient for road construction as well as for creation of soils with specified physical and physicalmechanical properties for other purposes.

Key words: sand; granulometric composition; triangular diagram; Feret triangle; physical properties; physical properties; physicalmechanical properties; density; porosity; angle of internal friction, optimum mixture; modeling.

Ter-Martirosian A.Z., Ter-Martirosian Z.G.

Experimental and theoretical basis of transformation of weak water-saturated clay soils at surface and deep compaction ...16

Experimental and theoretical foundations of transformation of weak water-saturated clay soils at surface and deep compaction of them are discussed. The article presents a solution of the problem of axially symmetrical consolidation of a weak water-saturated soil layer at surface compaction under influence of a sand dam or the equivalent vacuum, as well as at deep soil compaction during pilot hole reaming using various technologies. The author describes a solution of Lame's problem on estimation of the stress-strain state of a thick-walled water-saturated soil cylinder at specified displacement of the inner surface of a pilot borehole. Some examples of solution of these problems as well as nomograms based on the obtained formulae to determine the pore pressure, consolidation degree and excess pore pressure dissipation time are given.

Key words: weak water-saturated clay soils; surface soil compaction; deep soil compaction; axially symmetrical consolidation problem; weak water-saturated soil layer; Lame's problem; thick-walled water-saturated soil cylinder; pilot borehole; stress-strain state; pore pressure; consolidation degree; excess pore pressure dissipation time.

Seredin V.V., Krasilnikov P.A., Chizhova V.A.

Influence of the pore fluid (hydrocarbons) viscosity on the deformation modulus of clay ...26

Accidents sometimes occur during production, transportation and processing of oil and petroleum products. As a result hydrocarbons spill onto the ground surface. It leads to changes of foundation soil properties resulting in both increase and decrease of strength properties of sands and clay soils. However, many questions remain open, including influence of the pore fluid type on the deformation modulus of soil. Therefore, the aim of this paper is to study influence of the hydrocarbons viscosity on the deformation modulus of clays. It was experimentally found the deformation modulus decreases with increase of the pore fluid content in clay. Mathematical models for forecasting the total deformation modulus depending on the content of water, diesel fuel, engine oil, transmission oil in clay are calculated. Relationships between the hydrocarbons viscosity and the deformation modulus are revealed: the total deformation modulus of clay increases with growth of the hydrocarbons viscosity. Comparison of changes of the internal friction angle and deformation modulus at hydrocarbon pollution shows that the internal friction angle of sands and loams and the total deformation modulus of clays are subjected to the same regularity: the internal friction angle and the deformation modulus increase with growth of the pore fluid viscosity.

Key words: deformation modulus of soil; petroleum products; pore fluid viscosity.

Zdobin D.Yu.

The natural strength and deformability of clay soils. Part 2 ...30

Determination of strength properties of clay soils from the standpoint of the theory of natural strength of contact interactions (NSCI) is considered. Such property of the first order as the consistency of soil of natural structure is analyzed. The author argues that this characteristic is a particular case of such fundamental indicator of soil properties as the specific penetration resistance. Dependences of the specific cohesion and internal friction angle on the consistency of soil of natural structure and its flow index on the basis of laboratory determinations of physical-mechanical soil properties by the step penetration method were obtained. Charts and the corresponding summary table for determination of the strength parameters of clay soils (sandy loams, clay loams, clays) depending on the specific penetration resistance are presented. The author proposes to use the laboratory penetration method for engineering surveys for construction as one of the most objective and simple soil investigation methods.

Key words: clay soils; types of contacts between soil particles; physicalmechanical properties of soils; consistency index of soil of natural structure; specific cohesion; angle of internal friction; step penetration; relationship between parameters.

ENGINEERING GEOLOGY OF PERMAFROST

Vasil’chuk A.C., Vasil’chuk Yu.K.

Engineering-geological and geochemical conditions of polygonal landscapes in the area of the Tambey River mouth (the north of the Yamal Peninsula) ...36

The paper deals with the factors determining engineeringgeological aspects of development of the territories adjoining the South Tambey Gas-Condensate Field in the Yamal Peninsula (including widespread development of shallow location ice wedges) by the example of a licensed site of the field in the area of the Tambey River mouth. The relief, climate, hydrological conditions, geochemical features of bottom sediments of the Gulf of Ob, soils, geocryological conditions, cryogenic processes and engineering-geological conditions of the site are characterized. Subfossil pollen spectra, spore and pollen content, chemical composition of ice wedges and surrounding sediments are investigated, that permits to clarify the formation history of ice wedges. The character of enclosing soil deformations on the contacts with ice wedges is considered especially in detail. The macro ice content of the floodplain massif to the depths of 1 and 3 m and the potential subsidence at thawing of ice wedges are calculated. Comparison of the results of geothermal measurements in boreholes of 1978 and 2013 shows that the average annual temperature increased by more than 5 °С per 35 years.

Key words: Tambey River; Yamal Peninsula; engineering-geological conditions; geochemical conditions; polygonal landscapes; ice wedges; soil temperature; pollen; spores.

Valiev N.A., Kondratiev V.G.

Experiments on stabilization of the roadbed in the central part of the Baikal-Amur Mainline using awning roofs ...56

The current state of the roadbed in the section between Nalednyy and Khani of the East-Siberian Railway (ESRW) is characterized. The article describes experiments carried out in 2009–2015 that consisted in additional cooling of the permafrost soil massif in the base of the railway track using placement of awning roofs (sun-precipitation-protective sheds) on the railroad embankment slopes. The awning roofs proved to be technically and economically efficient.

Key words: Baikal-Amur Mainline (BAM); BAM central part; East-Siberian Railway (ESRW); permafrost soils; railway track deformations; subgrade stabilization; awning roof (sun-precipitationprotective shed).

SUPPLEMENT

From the book of "Mining Institute graduate's notes" by I.V. Arkhangel'skiy ...64

 

English abstracts ...78

 

 

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