Home – Home – Jornals – Earth’s Cryosphere 2022 number 6

The results of microscopic analysis of 118 samples of solid precipitation (snow) collected during the cold season of 2019-2020 at three key points in the neighboring Altai-Sayan and Tobol-Irtysh glaciological regions and on their border are presented. In 45 samples (38 %), advective pollen grains of trees (Betula sp., Pinus sp.) and herbs (Artemisia sp., families Asteraceae, Amranthaceae s.l. (incl. Chenopodiaceae), Fabaceae, Poaceae) were identified. Territories from which pollen grains arrived with air masses causing precipitation during the cold season were determined. Advective pollen of wormwood (Artemisia sp.) was brought from the territory of the Kazakh Upland and was determined in the snow of both glaciological regions and on their border. Pollen grains of Amaranthaceae s.l. (incl. Chenopodiaceae) were introduced from the plains of Kazakhstan and, partially, from the snow-free slopes of the Altai Mountains and from the Middle Ob Lowland. Pollen of Fabaceae family was only identified in the precipitation of the Altai-Sayan glaciological region, while pollen grains of Poaceae family were found in the precipitation of the Tobol-Irtysh region; in the border zone of the two glaciological regions, pollen grains of these taxa were not found.

Under natural conditions, soils of the active layer are open systems of varying composition, structure, and properties. However, in engineering projects, the values of thermal properties measured in laboratory on isolated samples of constant composition are used to describe their thermal state. To take into account the variability of the thermal properties of active layer soils under the influence of external factors, we propose a method for assessing the equivalent indicators of their volumetric heat capacity and thermal conductivity using a combined analysis of dynamics of soil temperature and heat fluxes based on long-term monitoring data. Monitoring of the heat flux and soil temperature has been carried out at two sites, one of which characterizing the area of seasonally freezing soils, and the other - the area of seasonally thawing permafrost-affected soils. A procedure for processing monitoring data is proposed, which makes it possible to determine the time-averaged effective values of the equivalent heat capacity and thermal conductivity. The proposed technique allows one to trace fluctuations of the equivalent heat capacity and thermal conductivity in time series against the background of changes in external factors of heat transfer in the active layer under natural conditions.

The construction of heated buildings in the Arctic is considered. To increase the bearing capacity of the foundations via their preservation in the frozen state, an environmentally friendly heat-insulating material obtained from the Arctic raw materials (opal-cristobalite and zeolite rocks) has been proposed. The aim of this work is to evaluate the efficiency of insulation layer made of granular foam-glass ceramic on the basis of numerical modeling of the thermal interaction between the heated building and the frozen base. We have investigated the influence of protective screens, construction parameters of a dome-shaped building, and the thickness of insulation layer on the thermal regime of a frozen base over 30 years in comparison with the option without the use of special engineering measures. Calculations indicate that the safe exploitation of a heated building without traditional seasonal cooling devices and a ventilated underground is only possible with the use of protective screens. The building can have the shape of not only a dome but also an elongated ellipsoid of unlimited length. In this case, for building width of 6-8 m, the thickness of insulation layer should be 1.0-1.4 m. The proposed technology is promising to reduce the cost of low-rise Arctic construction, rational use of mineral resources, and preservation of the permafrost and Arctic landscapes.

Glaciation of the northern Baikal region is associated with mountain ranges surrounding Lake Baikal. The underlying rocks are in the frozen state. The existing glaciers are remnants of a larger Pleistocene glaciation, and their area is subjected to continuous shrinking. The analysis of tree cores allowed us to reconstruct the climatic background of the glaciation changes in the recent past. A dendroclimatic curve is divided into two parts: the first part lasted until about 1860-1865, when the summer air temperature was almost always below the mean summer temperature for the entire considered period (~16 °С); the second part (until now) is characterized by higher (above-average) temperatures. During the field work, the current state of the regional glaciation was described for the areas of the Baikal, Barguzin, and Verkhneangarsk ranges. The areas of glaciation were determined from the Landsat 7 and Sentinel-2 satellite images for 2000 and 2021 and were controlled by orthophotoplans based on the UAV survey in August 2021. The maximum reduction of glaciated area over 21 years is generally typical for small forms of glaciation and reaches 10-30 % for the main glaciers. Data on temperature regime of air and rock surface along an altitudinal profile in the Verkhneangarsk Range were obtained for the first time.

This paper presents a retrospective analysis of the geometric electromagnetic induction (EMI) sounding data. The data were acquired in the 1990s in the city of Neryungri to determine probabilistic relationships between unconfined compressive strength of saturated sandstone samples and the attenuation coefficient of the harmonic field induced by a high-frequency vertical magnetic dipole at 1.125 MHz in frozen sandstone rock mass. The results indicate that the consistent increase in the attenuation coefficient with decreasing strength of sandstone rock mass is correctly described by a logistic function equation. The inverse regression relationship is adequately described by a power function equation which can be used as a probabilistic model for predicting mean values of unconfined compressive strength of saturated sandstone rock mass (but not only sandstone rock samples) from the attenuation coefficient. The relative error of model predictions at the 70-80 % confidence level is ±(27.7-32) %, which is close to the limit of allowable error (±20.0 %) for laboratory measurements of mean strength of rock samples. This provides favorable conditions for applying the geometric EMI method in rock strength mapping for geotechnical engineering in Neryungri, as well as in areas of similar geology in southern Yakutia with sporadic permafrost.

A recently published book by L.N. Khrustalev, a leading specialist in engineering geocryology, professor of the Department of Geocryology, Faculty of Geology, Lomonosov Moscow State University is devoted to methods for solving a wide range of problems of engineering geocryology: thermal and mechanical interaction of engineering constructions with bearing rocks, land reclamation measures, methods for assessing the reliability of design solutions for construction in the permafrost zone, as well as methods of predictive calculations for monitoring of objects built on permafrost. This monograph contains a wide range of recommendatory and standard calculations, as well as some previously unpublished author’s works. In essence, it is a desk reference for specialists involved in the design and calculations of engineering constructions on permafrost. Another highlight of the book is its electronic component: all the calculations proposed in the book are implemented in Microsoft Excel macros and are available for download and processing. This practically eliminates the possibility of errors (the user only needs to enter the correct input data).