DOI: 10.7256/2453-8922.2019.1.29380

Abstract: The object of this research is the exploration of anomalous sections of permafrost retreat at the soil baseline. In such cases, the apex of soil frost attains a complicated shape, forming the steep edges and mirrors of subpermafrost water. The authors propose a new  method of seismic survey  (0.5-1.0 kHz). The suggested seismic method modification is based on the joint application of the refracted and reflected waves in accordance with time curves of first onsets in their complicated shape, considering the below-cutoff angles of retraction within the depression. The time curves of the retracted waves were solved using the complex numbers; while their geometry remained traditional – the null time method  for determining the depth of refracting boundary and differential time curves for calculating velocities in the apex of depression. The modified seismic survey for studying the anomalous sections of permafrost retreat under the earth structures in cold regions was obtained and tested in the course of the research. It allows mapping out the local depressions with steep edges under embankments, occurred due to violation of the production sequence of transportation systems or normal exploitation of the structures built in such conditions. The surface seismic surveying using the method of retracted waves, and particularly, conducted via the null and differential time curve have a potential for modification depending of the current objectives. In the conditions of below-cutoff angles of waves retraction, the tasks on determining the subsurface depressions are solved mathematically, with application of complex numbers; at the same time, the basic conditions for the method of retracted waves, such as coordination of time curves in mutual duration and the precision of determination of the average velocities remain unchanged.  

DOI: 10.7256/2453-8922.2022.1.29498

Abstract: When studying landslide processes, researchers pay great attention not only to the geometric dimensions of landslide bodies, displacement mechanisms, geomorphological features and reasons for their activation, but also to the time of their activation. The data obtained by radiocarbon dating of organic material selected from various geomorphological elements of landslides in the upper reaches of the Mzymta river basin (Western Caucasus) with a large sample of samples allow us to confidently say about the age of the event, or several episodes of landslide formation, the frequency of repetition of the process, as well as to establish the trigger causes that triggered the landslide. To obtain more reliable definitions of the age of the landslide, a method for performing serial selection of organic matter has been developed. Organic material was selected from various elements of the landslide : a) from sections of depressions in the rear part of the landslide, b) from sections of depressions on the main body of the landslide, c) from the humus horizon buried under the lingual part of the landslide. More than 40 new dates of samples of organic material have been obtained. The chronology of late- and Mid-Holocene landslides in the valley of the Mzymta river has been performed: 1. Landslides located on the northern slope of the Aibga ridge were formed during two major stages of landslide formation; 2. The older stage of landslide formation dates from the Middle Holocene from 6310 to 5380 cal. 3. The relatively younger stage of landslide formation dates from the Middle Holocene from 2930 to 2820 cal. years ago.

DOI: 10.7256/2453-8922.2022.1.37649

Abstract: The subject of research is the earthwork of the railway track and artificial structures on hazy weak-draining areas in the areas of permafrost distribution on the bypass of the Bureyskaya HPP reservoir within the Verkhnebureinskaya depression. The purpose is to identify the conditions and causes of adverse processes and phenomena that have arisen during operation. The objectives of the research are to identify the main causes and conditions for the manifestation of unfavorable geocryological processes and phenomena – waterlogging, flooding, stagnation of water, degradation of permafrost, sediment of the roadbed. Design errors are analyzed and recommendations are given for the application of design solutions in accordance with the state and dynamics of geocryological conditions and the requirements of the current regulatory documents for the areas of distribution of low-level marys and high-temperature permafrost. For the first time, a comprehensive analysis of the conditions and causes causing adverse processes and phenomena was carried out for the described territory. Inefficient constructions and design solutions have been identified. Optimal design solutions and measures are recommended to ensure the stable and safe operation of transport facilities in the region in conditions of low-drainpipe and high-temperature permafrost. For the studied area, the characteristic features are the significant swampiness of the territory, and the wide distribution of low– and high-temperature permafrost soils of the merging type. There are cases of irrational and inefficient design. It is not uncommon to use unsuitable soils for filling the roadbed and its elements. Also, the excess of the volume of earthworks during construction. Under these conditions, it is recommended: When designing a railway track plan, trace the line through local elevated terrain areas, in order to ensure the necessary slope of the design profile of drainage ditches of at least 4 ppm. Drainage ditches along the path should be located at a distance that excludes the inflow of water into the base of the roadbed.

DOI: 10.7256/2453-8922.2020.2.32405

Abstract:   This article is devoted to the mathematical modeling and computing experiment in problems of temperature fields forecast in continuous foundations in cryolithozone, which will provide a qualitative approach to non-stationary thermal calculations for making design decisions to ensure the stability and reliability of bases and foundations of buildings in the Arctic zone.  The article formulates the problem of forecasting by determining changes in the temperature, areal distribution, thickness, and vertical structure of permafrost, seasonal and perennial freezing of the soil, their temperature strength state, and properties in connection with the construction of buildings. Presented mathematical calculations are based mainly on the assumption of a non-stationary process of heat exchange. Mathematical models for determining depth of thawing are considered. The problem of determining the temperature in the basement of the foundation, limited on the one side, in which the temperature depends on only one coordinate with the condition that the surface temperature of the permafrost soil undergoes periodic fluctuations around zero value under the influence of external influences, has been solved. It is demonstrated that the two-dimensional problem of permafrost ground with a semi-infinite foundation thickness can be generalized even more. The problem is formulated in the form of a differential equation of heat balance taking into account the heat flux, which varies according to the Fourier’s law.  

DOI: 10.7256/2453-8922.2020.3.32222

Abstract: The object of this research is the examination of stability of volcanogenic-sedimentary and effusive rocks in the mine workings of Kupol Deposit. The subject of this research is the analysis and assessment of the physical and mechanical properties of these rocks in the solid, considering the intensity of fracturing and the degree of their water content, using the indicators developed by Professor N. S. Bulychev and Professor G. L. Fisenko. The data acquired in real assessment of the state of rock mass prove the choice of applied ground support at Kupol mine. Research methodology is based on the analysis of structural-tectonic peculiarities of Kupol deposit, which defines the high degree of disintegration of complex set of rocks and dictates the need for development of staging approach towards characterization rock stability in mines – from the samples to the full array. The scientific novelty lies in the fact that this work is first to implement phasic approach towards evaluation of stability of the rocks in Kupol mine for transition from the results of laboratory studies of rock samples to assessment of their actual behavior during the exploration of the deposit in severe mining, geological and hydrogeological conditions. It is noted that the Deposit is associated with the volcano-tectonic depression of the Okhotsk-Chukotka volcanic belt, complicated by younger volcanogenic tectonic activity, and is located in the zone of the Middle Kayemraveemsky fault of 1st level of latitudinal outstretch. Analysis is conducted on the implemented system of field development in complex mining and geological conditions.

DOI: 10.7256/2453-8922.2022.3.38777

EDN: HNHLEU

Abstract: The design and construction of highways in the cryolithozone is associated with a number of difficulties, which are determined not only by geocryological and climatic operating conditions, but also by the complexity of the actual forecast of the thermal regime of road coverings and foundations. Many thermal calculations to substantiate technical solutions for the protection of highways in the cryolithozone from negative cryogenic phenomena are based on the determination and selection of a given thermal resistance of the structural layers of the pavement. The purpose of these studies was to assess the feasibility of using equivalent thermal resistance in modeling thermal processes and to determine the error in calculations that we make by replacing the layered pavement structure with an equivalent one.     Simple engineering dependences are obtained that allow us to determine the error in calculations when using equivalent thermal resistance. The calculation of the thermal resistance of the three-layer construction of the pavement is made. It is established that for a three-layer pavement structure, the error value in the calculation of thermal resistance is directly related to the degree of deviation of the values of the thermal conductivity coefficient of the materials of individual layers from each other. Moreover, the parameters of the inequality of thermal conductivity coefficients for individual structural layers when determining the minimum calculation error are functionally related to each other. The results of variant numerical calculations are presented in the form of 3D and 2D graphs, which allow us to visually assess the influence of the studied parameters on the relative error of calculating the thermal resistance of the pavement.