No 5 (2019)

Accumulation capacity of soluble rocks as the main stability index in covered karst areas
Anikeev A.V.
Abstract

For an engineering geologist, covered karst areas are of special interest, not only because these are the most widespread on the Earth. More important, unlike the areas of bare karst, these areas are more favorable and suitable for economic development and human life as a whole. And the study shows that the greater is the thickness of the cover series, the more true is this statement.

The local forecast of sinkholes appears to be the most important and difficult engineering geological problem in these areas. It is especially acute there, where collapses and subsidence are absent, not registered, or poorly expressed in the relief, that is, in the areas of unrealized (potential, expected) sinkhole hazard. One of the possible approaches to solving this problem is discussed in the paper. It is based on comparing the volume of incoherent and fractured rock removed from the cover deposits with the accumulation capacity of the karst massif, i.e., the volume of hollow space in the karstic massif capable of receiving and accumulating clastic material.

The most common result of soils outflow in fissure-karst reservoirs is their loosening in the deformed-destructed area of the overburden. For the three canonical schemes of this area structure, the critical values of clastic matter volume were obtained from the equation for soil mass balance before and after loosening, the further removal of which will lead to the failure of the earth's surface. Some techniques and methods for assessing the accumulation capacity of soluble rocks are considered and serious differences in the use of the discussed approach in predicting the stability of karstified and undermined territories are revealed. In particular, it is shown that in karst areas, when performing calculations, one should be guided by the maximum values of the coefficient of primary loosening of soils. Otherwise, the predicted stability of the overburden will prove to be unjustifiably underestimated. The results obtained and the procedure for assessing the stability of covered karst terrains by the proposed method are exemplified by the construction site of the main buildings of the Nizhny Novgorod NPP (3.25 km2), where there are no collapse and subsidence sinkholes. However, the entire construction site (20 km2) is located in the area of active sulphate-carbonate karst. From the engineering-geological point of view, this is the main feature of the facility design.

Геоэкология. Инженерная геология. Гидрогеология. Геокриология. 2019;(5):3-14
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Natural and human-induced processes
Assessment of the geoenvironment stress state at the Caucasian mineral waters test plot using long-term seismic-ecological monitoring
Popova O.G., Popov M.G.
Abstract

According to the results of continuous long-term seismic-ecological monitoring at the Caucasian Mineral Waters test plot (the seismic zone in the Cis-Elbrus region), data on the seismic velocity distribution pattern were obtained for the test plot territory. The high-speed structure is revealed, the horizontal dimensions of which do not allow predicting local earthquakes with a very high magnitude in this territory. Three-dimensional models of anisotropy index γ were obtained and the indexes of stress state S were estimated for different depths according to the interpretation results of converted PS waves from distant earthquakes. It is found that the distribution of the anisotropy index γ varies continuously by the depth, by the laterals and in time. The cyclic changes in the index S with time are noted for all depths.

Геоэкология. Инженерная геология. Гидрогеология. Геокриология. 2019;(5):15-22
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Influence of shaking intensity attenuation peculiarities on reliability of earthquake loss estimation in emergency mode
Frolova N.I., Gabsatarova I.P., Petrova N.V., Ugarov A.N., Malaeva N.S.
Abstract

The methods and results of seismic hazard zoning are investigated for the Russian Federation territory and abroad. The input data used in the zoning procedure, aimed at revealing the boundaries of areas with stable seismic intensity attenuation parameters have been analyzed. The zoning procedure has been developed for determining the boundaries of territories, within which the macroseismic field parameters (i.e., the coefficients in N.V. Shebalin’s equation; the orientation of the elliptic isoseist axes, as well as the ratio of their semi-axes) show close values in each point. Examples are given in distinguishing zones characterized by quasi-stable parameters for separate regions, as well as in calibrating the computer model of the macroseismic field. The case studies are considered in the presence of a complete set of input data and under conditions of their insufficiency. The efficiency of the macroseismic field calibrated models application in the Extremum system in order to increase the reliability of near real time earthquake loss estimations is shown.

Геоэкология. Инженерная геология. Гидрогеология. Геокриология. 2019;(5):23-37
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The impact of Sochi – Imeretinsky harbor on the coastal processes (the Black sea)
Petrov V.A., Yaroslavtsev N.A.
Abstract

The impact of the harbor built near the Mzymta river mouth on the pebble sediment transport along the coast and the coastal line transformation is assessed proceeding from the survey data comparison. Sediment accumulation in the wave chamber of the permeable southwestern barrier pier are considered and the possibility of its circumvention by pebble material is estimated. It is shown that the sediments transported along the pier penetrate into the numerous canyon openings and go deeper. As a result of the bottom erosion behind the port, the pebble beach in front of the shore-protective structure protecting the embankment from the waves has disappeared at the 1-km-long coast site, and its erosion continues. The absence of a wave-setting pebble beach poses a threat to the destruction of the coastal protection structure and the embankment.

Геоэкология. Инженерная геология. Гидрогеология. Геокриология. 2019;(5):38-47
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Soil and rock engineering
Physico-chemical nature of clayey soils strength
Karpenko F.S.
Abstract

The principles of soil mechanics based on Mohr–Coulomb strength theory and Terzaghi effective stresses theory give us the idea about the nature of clay strength. However, these theories consider the clay as a solid body and do not take into account their internal structure. In the present paper, the problems in determining the strength of clayey soils are considered from the standpoint of the physicochemical theory of effective stresses. This theory is based on the ideas of the internal structure of clays. The main idea implies that the structure of clays depends on the contacts formed between mineral particles, where the external stresses transmitted to the soil are concentrating. Water in clayey soils not only fills the pore space but also interacts with the mineral particles forming hydrate films around them. The prevailing type of structural contacts in clays determines the properties of latter. Strength is an intrinsic property of soil determined by its composition and internal structure, independent of the conditions of load application to it and characterized by the actual effective strength value. The value of actual effective strength in clays is determined by the total strength of individual contacts. This is the maximal stress transferred to the soil contacts, the structure being ruined upon exceeding this value. The actual effective strength in soils with the same predominant type of contacts depends on the number of contacts. The numerical strength characteristics of contact types are determined for different clay soil varieties to characterize the actual effective strength. The parameters of relationship between the actual effective strength in clays and their strength characteristics are obtained from the soil testing by standard methods.

Геоэкология. Инженерная геология. Гидрогеология. Геокриология. 2019;(5):48-60
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Research methods and techniques
Remote assessment of natural hazards on the base of the mathematical morphology of landscape
Victorov A.S., Orlov T.V., Sadkov S.A., Trapeznikova O.N.
Abstract

The aim of this paper is to show approaches for the quantitative evaluation of natural hazards using the remote sensing data and basing on the results of the mathematical morphology of landscape. The mathematical model of the morphological pattern for lacustrine thermokarst plains with fluvial erosion was taken for the decision of the problem in case of an asynchronous start of the thermokarst process with the continuous generation of new thermokarst depressions.

The mathematical analysis of assumptions taken in the model gives us the regularities of the morphological pattern for the thermokarst plains with fluvial erosion including exponential distribution for khasyrei areas, integral-exponential distribution for lake areas, and the Poisson distribution for a quantity of either khasyreis or lakes within the key sites. Besides, analyzing the development of the territory in question by the approaches used in mathematical morphology of landscape we found out that in case of asynchronous start under very general conditions a dynamic equilibrium is established in generating thermokarst lakes and turning them into khasyreis after a long time. At the same time, the distribution density of thermokarst foci and their sizes, as well as process damage and the dimensions of khasyreis tend to some final levels specified by the expressions described above.

The results obtained were empirically tested at 17 key sites. Generally, the empirical testing shows that the asynchronous start takes place within thermokarst plains with fluvial erosion at a sufficient number of sites, and the theoretically obtained regulations are valid.

The regulations obtained were used for the mathematical solution of the probabilistic task for damage of a linear structure crossing the thermokarst plain with fluvial erosion.

Геоэкология. Инженерная геология. Гидрогеология. Геокриология. 2019;(5):61-73
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Evaluation of seismic properties of water-saturated soils for solving problems in seismic microzoning
Trifonov B.A., Sevostyanov V.V., Milanovskiy S.Y., Nesynov V.V.
Abstract

The experts involved in seismic microzoning (SMZ) have different opinions on whether to take into account the response of water-saturated fine soils upon the assessment of expected seismic effect. When using the method of seismic stiffness (MSS), a number of researchers consider inexpedient to apply the correction for the groundwater level (GWL). In the present paper, we analyze both the results of our own field studies and those of other researchers involved in the development of SMZ methodology. Particular attention is paid to the GWL influence on the increment of seismic intensity (ΔIGWL ) in the S.V. Medvedev’s equation upon MSS calculations by transverse s-waves. The research results provided in this paper prove that the correction for ΔIGWL should not be ignored in calculations of the seismic intensity increment. The authors appear it expedient to continue field tests in the registration of strong movements in water-saturated fine soils.

Геоэкология. Инженерная геология. Гидрогеология. Геокриология. 2019;(5):74-81
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Significance and technological capacities of natural study of the ground pore pressure dynamics under the freezing and thawing conditions
Ginzburg А.А., Kal’bergenov R.G., Isaev V.S., Tipenko G.S., Sergeev D.O., Khimenkov А.N.
Abstract

Actual geotechnical monitoring systems and models of geocryological processes are aimed at assessing and preventing hazardous dynamic impacts on infrastructure facilities in the Arctic and Subarctic of Russia. The level of methodological support and hardware development of these systems are insufficient in Russia in the context of a changing climate, growing environmental impact and decreasing quality of geological survey and design. Pore pressure is successfully studied at the sample level in the laboratory and in the field by using the static sensing method, however, the dynamics of pore pressure and the physical patterns of this dynamics in soil massifs remain studied inadequately. For theoretical reasons, pore pressure should change under the influence of processes associated with freezing and thawing, and, consequently, it should affect the intensity of gas hydrate dissociation as well as the mechanical properties of soils. The modern technological base provides new opportunities for the study of the pore pressure dynamics in the soil mass. This opens prospects for improving geotechnical monitoring systems for the protection of infrastructure facilities from adverse natural and man-made impacts.

Геоэкология. Инженерная геология. Гидрогеология. Геокриология. 2019;(5):82-88
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Discussion
About fundamental losses in engineering geology
Osipov V.I.
Abstract

The paper considers the viewpoint of the author, i.e., the full member of the Russian Academy of Sciences Prof. V.I. Osipov, on the problem raised by Prof. V.T. Trofimov, the head of the Department of Engineering and ecological geology at the Moscow State University, in his article published in “Inzhenernaya geologiya” journal, about the losses in engineering geology in the last decades. Both the objective and subjective reasons of this science degradation are mentioned.

Геоэкология. Инженерная геология. Гидрогеология. Геокриология. 2019;(5):89-91
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