Permafrost covers 65% of Russia’s territory. Cryolithozone is the upper part of the Earth's crust. It usually contains ice, frozen water and various gases. Despite the name, these territories contain the richest natural resources in the country. Nowadays a developed infrastructure operates on these territories. Special technologies are actively used for its preservation and construction.
At first glance, life in permafrost may seem unattractive mainly because of the rather harsh climate and the lack of opportunity to cultivate the land. However, there are many more features to be aware of. For example, traditional burials are prohibited in permafrost. In these natural conditions, the bodies will not decompose and may attract predators. Speaking of which, a person without shooting and self-defense skills would have a hard time living in these areas. For the same reason, it is undesirable to have cats in the Arctic zone, as they irritate bears.
Foreign northern lands are extremely sparsely populated. For example, two thousand inhabitants of the Norwegian Longyearbyen live in a constant struggle with nature. At the same time, they also have no medical infrastructure. However, our country has developed large cities in the permafrost zone. The population of Murmansk, Yakutsk, Vorkuta and others began to grow rapidly back in the Soviet years. The infrastructure was also developing along with the population growth.
Nowadays Norilsk and Dudinka have also become major Russian cities in permafrost. 170 thousand people live in Norilsk and 20 thousand in Dudinka. Norilsk is a major center of non- ferrous metallurgy. It is also among the top three most comfortable Russian cities located in a harsh climate. Dudinka, in turn, is Russia's northernmost international port. Norilsk and Taimyr are located entirely in the permafrost zone.
"The conditions here are heterogeneous: permafrost extends to a depth of up to 500 meters, some areas are occupied by unfrozen layer (the so-called talik), and the average annual temperature of the rocks varies from minus five to plus seven degrees. All this leaves an imprint on construction conditions," says Giorgi Kunchulia, an expert of the Adaptation Department of Scientific Research in the Field of Climate Change of Nornickel.
The upper layer of permafrost seems to be stable. In reality, the permafrost is mobile and dynamic. Therefore, it is difficult to carry out construction in this region. The biggest problem for builders is global warming and climate change. They cause thawing and permafrost degradation. According to the Ministry of Natural Resources, about 40% of the infrastructure in this zone is under threat of degradation. It may cause damage of 5 trillion rubles by 2050, and this - is only preliminary estimates.
Foundation stability and maintenance of a constant temperature regime are the basic principles of construction in these conditions. Design mistakes and improper operation can accelerate the thawing process. This eventually leads to the destruction of buildings. For this reason, almost immediately after the city was founded in 1936-1937, the first temporary buildings in Norilsk quickly collapsed. Among these buildings were a wooden nickel electrolysis shop and barracks.
In those years, experts believed that the solution for the erection of industrial and civil buildings would be the construction of a ground floor with underfloor ventilation. They also suggested reinforced concrete columns or wooden piles embedded into boreholes as building supports. The technology turned out to be imperfect. First, the builders had to thaw the ground, then install the pile, and afterward, they had to wait a long time for the permafrost to recover. In 1959, a new technology was introduced by hydraulic engineer Mikhail Kim. Since then, builders began to erect houses on piles, the wells for which were drilled directly into the permafrost.
"At the same time, there are quite a lot of ways to build and provide thermal insulation. For example, construction on piles with underfloor ventilation, erection of buildings and structures on fill with surface heat insulation, arrangement of cold first floors, and use of seasonally active cooling devices or thermal stabilizers. Most of the buildings in Norilsk are built on piles with underground ventilation," explained Kunchulia.
Today, before choosing a suitable principle of construction, specialists conduct a whole complex of engineering surveys and a careful engineering process.
According to Sergey Goshovets, Deputy Head of the Department of Scientific and Technical Research, Information Technology and Economic Support of the Federal Road Agency, deformation processes are accelerating on several highways in the permafrost zone, namely on the A-331 "Vilyui", R-504 "Kolyma", A-360 "Lena", and R-297 "Amur". In 2012, 313 pavement defects were detected on R-297 "Amur" and, despite prompt work on their elimination, this figure increased to 504 by 2015.
According to Mikhail Zheleznyak, Director of the Melnikov Permafrost Institute of the Siberian Branch of the RAS, the variability of the cryolithozone is the most difficult moment for road builders. To prevent ground deformation, road builders make efforts to isolate structures from water and heat: they lay Penoplex (heat-insulating material) on the subgrade foundation, protect embankment slopes from the sun and precipitation with cantilevered sheds, and install pipes that transfer natural atmospheric cold to the road foundation.
The unique Zapolyarye – Purpe – Samotlor Oil Trunk Pipeline is one of the examples of new developments. It was commissioned in Russia in 2017. As much of its territory is above ground, special pile-based supports were developed for the project: fixed, longitudinally sliding, and free-moving. Thanks to this new technology, the pipeline can move slightly without deformation. The supports are equipped with soil thermal stabilizers that maintain the natural soil temperature. This development of Russian specialists is protected by several dozens of international patents.
The implementation of new construction technologies requires serious research work. Already this year, Nornickel, together with the Research Center for Construction Technologies and Monitoring of Arctic Buildings and Structures of Fedorovsky Polar State University, is creating two permafrost landfills. One of them will be used to test construction technologies on permafrost soils and new types of foundations. It will also be used to verify geophysical methods. Specialists will apply the obtained data to build predictive models.
"All over the world, a system of geotechnical testing grounds with a wide range of geological soil conditions has been created to test and verify innovative construction methods. However, there are only a few such testing grounds in the cryolithozone. Norilsk will be one of the first regions to have its test site," says Giorgi Kunchulia.
In 2023, 30 pilot observation stations will also be installed in the Russian North. The entire system of 140 stations will implement strategic plans for the development of the Arctic zone of the Russian Federation.
Russia will launch a comprehensive permafrost monitoring system within the next three years.
"Permafrost thawing may bring significant adjustments to the activities of entities and entire industries, create risks for preserving the integrity of infrastructure facilities, including oil wells, pipelines and others. The main aim of monitoring is to timely record current changes, analyze them and facilitate prompt adoption of appropriate decisions," explained Dmitry Kobylkin, Chairman of the State Duma Committee on Ecology, Natural Resources and Environmental Protection.
A similar system was used in the USSR. However, it ceased to exist immediately after the collapse of the Soviet Union. The number of monitoring stations in those years was equal to 20. At that time, several studies were conducted under the guidance of authoritative Soviet engineers and permafrost scientists working at the Vorkuta permafrost station. The research groups were headed by Vladimir Yanovsky, Leonid Brattsev, and Vladimir Kudryavtsev. Specialists investigated the properties of permafrost soils for the future development of coal mines. They created new methods for the construction of residential buildings and the Vorkuta- Kotlas railroad and conducted experiments on farming in the Polar Region. The Vorkuta permafrost station became a major strategic industrial region and the polar city of Vorkuta.
Permafrost monitoring occupies a special place in Nornickel's operations. It ensures the reliable operation of the Company's facilities and environmental protection. The temperature should be monitored monthly during the construction phase of the project and no more than twice a year during the operational phase. But Nornickel has additionally launched an automated monitoring system. It includes large-scale studies of soil composition and properties, restoration of the network of observation thermometric wells in the region, comprehensive inspection of foundations and structures, identification of defects and deviations, and development of geotechnical monitoring programs. As part of this work, various sensors and instruments, including thermometric streamers, thermo hygrometers, and inclinometers, are being installed in the company's facilities. A centralized system of data collection, transmission, storage, processing and analysis is being actively implemented. Remote sensing technology is also being tested to qualitatively assess the magnitude of vertical displacements. As a result of this work, the approaches to design and construction have changed. Now all new facilities are necessarily automated and included in the informational diagnostic system.
In 2022, implementing the state program of background permafrost monitoring, the Polar Division of the Company (Norilsk Nickel) started drilling deep 200-meter wells. The Polar Division restored a 1960s well in Norilsk and drilled four new ones in Talnakh, Kayerkan, Oganer and Dudinka.
The second joint test site of Nornickel Company and the Polar State University will be located in an undisturbed (natural) area. It will be used to test background monitoring techniques.
"Our actions will allow us to assess the impact of anthropogenic and climatic factors on permafrost over the last 60 years and develop economically feasible adaptation measures," concluded Giorgi Kunchulia.
Based on the rbc.ru materials