№ 6 (2024)

The authors identified the main features of continental (land) ecological-geological systems (EGS) of hydrothermal soil massifs at the local level using the example of thermal fields in the south of the Kamchatka Peninsula — the East Pauzhetsky geothermal field. The field is located on the northwestern slope of the Kambalny volcanic ridge at an altitude of about 300 m above sea level. It has a shape elongated in the sublatitudinal direction with linear dimensions of the order of 350×100 m. From the surface, the thermal field is composed of hydrothermal clays formed due to the complete degeneration of andesites during interaction with gas–hydrothermal fluids. The abiotic and biotic components of the EGS data were analyzed. The specific features of the lithotopes of the considered EGS, represented by massifs of hydrothermal-metasomatic soils with a certain topography, a characteristic hydrotope, as well as geochemical, geodynamic and geophysical fields developed within their boundaries, have been established. The characteristic features of the lithotope of the EGS under consideration are: 1) the essentially clayey composition of the soils in the uppermost part of the section; 2) elevated temperature causing a temperature anomaly; 3) acidic–slightly acidic environment of pore solutions in the near-surface horizon and alkaline at depth; 4) changed (compared to parent rocks) characteristics of structure and texture, indicators of physical, physico-chemical and physico-mechanical properties. Lithotopes, in turn, determine specific edaphotopes on their surface, as well as the development of peculiar biocenoses: thermophilic microbiocenoses, communities of characteristic plants and animal thermophiles. The EGS of hydrothermal soil massifs is characterized by horizontal zoning, which manifests itself in all of its components and is caused, first of all, by the presence of a zonal temperature anomaly in the hydrotherms under consideration. The main determining factor in the formation of the specific features of this EGS is the originality of its lithotope, represented by an array of hydrothermal-metasomatic soils with vertical and horizontal zoning. The identified features in the composition and structure of the analyzed EGS must be taken into account during engineering and environmental studies and engineering and environmental surveys at similar objects.

In the mathematical description of sinkhole distribution with time, sinkholes are considered as random discrete events. The diameter of funnels is the main indicator of sinkhole impact power on the environment, and the intensity of sinkhole occurrence is the main probabilistic index. Most generally, the risk of losses from karst-suffosion sinkholes is the product of subsidence probability by the damage caused by a recipient object deformation or destruction. Formulas of direct damage and vulnerability have been derived, allowing for a unified assessment of physical and economic losses from damage to engineering and territorial facilities caused by geological processes. Two currently used stochastic models of sinkhole formation in covered karst areas are considered, i.e. exponential and linear models. It is shown that with the intensity of the process and the area of risk recipients less than 0.1 year^–1⋅km^–2 and 10 ha, respectively, these models give close values of the probability of damage to recipient objects. The linear model, written as a system of two equations, is devoid of some of its disadvantages and allows one to predict the risk of losses in case of non-compliance with Poisson’s law. In the article, the assessment of the risk of radioactive emissions and out-of-design accidents at the site of the projected NNPP power units is based on data obtained during surveys on 14 sinkholes formed over 53 years in an area of 50 km², in the center of which the industrial site is located. The Poisson flow of events is found to take no place in this area, and a linear risk model has been chosen for the forecast, written as the product of the frequency of sinkholes occurrence under the four main structures of the NNPP by their vulnerability. Taking into account some assumptions and design features of engineering facilities, it is shown that the risk of their beyond-design accidents and the risk of radiation emissions at the industrial site are many times less than their permissible values specified by regulatory documents on the use of atomic energy in Russian Federation.

The paper considers the peculiarities of changes in geocryological conditions on the section “288 km” of the “Amur” highway Chita–Khabarovsk. A comprehensive analysis of cryogenic processes and deformations of the roadbed in the conditions of formation and functioning of a special natural-anthropogenic “highway” system has been carried out. A landscape-geocryological schematic map has been compiled with the boundaries of the natural- anthropogenic system and zones of influence outlined. Engineering geocryological profiles of the deformed section of the highway was built on the basis of seven drilled wells with a depth of 7.5 to 30 m. Thermometric observations were carried out in five wells with the study of the peculiarities of temperature distribution under and near the roadbed. Studies have shown that the causes of deformations of the roadbed are heterogeneous, multidirectional and uneven changes in geocryological conditions as a result of the spatiotemporal formation and development of interdependent natural and man-made processes in the natural-technical system. A number of organizational measures have been proposed to control changes in geocryological conditions and the development of the natural-anthropogenic “highway” system in local areas.

The purpose of this study is to investigate the possibility of quantifying the dynamic parameters of landslide processes of abrasion shores in the cryolithozone by analyzing the morphological pattern of these shores taken from a single space survey. The empirical study was carried out at six key sites within the Kanin Nose, Gydan, and Yamal peninsulas. As follows from the analysis, the probability distribution of the thermocircus sizes observed at each moment differs from that of young thermocircuses (and, respectively, landslides) formed due to the erasure of a part of a thermocircus or its complete erasure in the process of the coastal development. The results of the mathematical modeling show that in the case of an abrasion slope with relatively homogeneous geological and geocryological characteristics, a dynamic balance is achieved, which is manifested in the stabilization of the average size of thermocircuses and stabilization of the probability distribution of their sizes along the slope extension. The analysis of empirical data at the studied key sites showed that the observed trends in the average size of the thermocircuses correspond to the conclusion about the existence of the dynamic balance in the development of the coastal morphologic pattern. The study’s main result is the analytical dependence, which gives a principal possibility to determine the probability distribution of the sizes of young landslides based on the morphological pattern of abrasion shores observed from the single space survey without stationary observations. The morphological pattern of abrasion shores does not determine the generation density of forming landslides. The result of the study can be used in forecasting shoreline retreat and predicting landslide processes on abrasion shores of the cryolithozone.

Soil massifs have close contact with foundations, piles, enclosing and fixing structures (anchors, dowels, retaining walls), as well as reinforcing soil during grouting with injection veins. Many bodies are composed of hardening cement that has an interfacial boundary with the soil. The soil–material system can be considered as a composite, in which the components exhibit new qualities when interacting. Experimental studies of cement interaction with enclosing fine soil and hard rock have been performed. The interaction specifics controlled by the material, the concentration of the binder, the surface type, watering, as well as mutual penetration of cement and enclosing rocks are studied. Special methods of shear testing based on soil samples of pile models made of cement material have been developed. The results of studying the effect of smooth and rough surfaces upon waterlogging are presented; the values of friction coefficients, contact cohesion, and stickiness are given. A dependence is proposed for determining the limit shear stresses of composite models upon the contact between sands and hard rocks with the material of dies. For rocks in which the hardening of the pile material was modeled, the values of the limit stresses and shear strain modulus were obtained depending on the binder concentration in the cement mortar.

The content of dissolved substances, C_org, hydrocarbons, phenols, toxic metals and arsenic are studied in water, bottom sediments and soil of the catchment area of the small urban river Polezhaevka (Khabarovsk). A positive relationship is revealed between the content of C_org and the fraction of 0.01 mm particles in soil. Along the vertical profile of the soil, a decrease in C_org is accompanied by an increase in the content of metals (cadmium, copper, nickel, mercury, lead, zinc) and arsenic. The content of hydrocarbons in water did not exceed 0.18 mg/dm³ (3.6 MPC); in bottom sediments they were within the limits of permissible hydrocarbon overload of self-purifying capacity C_HC / C_org = 0.07–0.43; and their content did not exceed 141.6 mg/kg in soil. The coefficient of bottom accumulation in terms of iron, manganese, lead and zinc is characterized as “the entry of fresh pollution into a water body.” The information obtained is useful for assessing the geochemical consequences of flooding the floodplains of small rivers and for planning measures on revitalization of urban small rivers.

It is proposed to classify areas of contaminated geoenvironment in the territories of oil complex enterprises and the methods used for removing hydrocarbons depending on the depth. A set of technologies has been developed and introduced into construction practice that make it possible to remove hydrocarbon-containing pollution without soil extraction in the territories of reconstructed and closed oil complex facilities. Elements of the technological scheme for washing soils for various conditions of occurrence of hydrocarbon contaminants are presented.