FOUNDATIONS
City of Yakutsk
Yakutsk is the largest and oldest city on permafrost (founded 1632; population ~ 323,000; area 122 km2). It is located within a valley of the middle Lena River in central Yakutia (62°01′38″ N, 129°43′55″ E). Most of the city lies on a low river terrace, 5 to 10 km wide, above the current floodplain. Permafrost in the Yakutsk area is continuous in extent and varies in thickness from 250 to 422 m. There are over 37,000 buildings and structures in the city, with foundation systems ranging from slabs-on-grade to pile foundations.
Yakutsk CHP
The Yakutsk Combined Heat and Power Plant was constructed in 1937 in the northeastern part of the city on the bank of a side channel of the Lena River. It was the first large industrial facility in the country built on permafrost using the passive construction method, i.e., keeping the supporting ground in its frozen state. Prior to construction, the permafrost varied from 180 to 200 m in thickness, and the mean annual ground temperature at 15 m depth ranged from -3 to -5ºС. In order to keep the foundation frozen, the building was founded on column footings with a 1.2 to 1.8 m ventilated air space between the ground and the structure. In the 1960s-1970s, twenty three Gapeev thermosyphons were installed to stabilize the permafrost. However, talik development due to leakage incidents remains an issue.
Long-term thermal monitoring has been conducted since 1982 to detail the ground temperature field and to determine trends in its dynamics. Currently, ground temperatures are measured quarterly in 90 boreholes to a maximum depth of 20 m. Surveying of settlement markers (over 100) is conducted before each thaw and freeze season to monitor vertical displacements of the foundation elements.
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Ground temperature distribution |
Ground temperature distribution |
Read more
Zabolotnik P.S. (2020). Contribution of permafrost scientists to ensuring long-term and trouble-free operation of the Yakutsk CHP Plant. In: Environmental and Infrastructure Integrity in Permafrost Regions: Proceedings of the Russian Conference with International Participation on the Occasion of the 60th Anniversary of the Melnikov Permafrost Institute, Yakutsk (Russia), September 28–30, 2020, pp. 396-399 [in Russian]
Reclaimed Floodplain, Districts 202 and 203
Districts 202 and 203 are housing projects on dredged hydraulic fill in the floodplain of the Lena River. Fill, 8.5-10 m over bars to 12-14 m thick over oxbow lakes, was placed in 1980-1988, with additional earthworks in 1990-1992 and 2012. District 202 was designed and constructed in the 1990s on the principle of maintaining the underlying permafrost in its frozen state. However, geothermal observations conducted by MPI from 2009 to 2015 showed that foundation soils were unfrozen down to depths of 10–15 m over much of District 2020 due to the combined effects of natural and anthropogenic factors (leaks from water supply and wastewater lines, percolation of rain and melt water, complex groundwater processes, hydraulic connection with the river, warming effect of the fill mass, and freeze-thaw-induced changes in mechanical and strength properties of the fill material). Buildings in the neighboring development, District 203 (construction began in 2014), are designed to allow thawing in the foundation. MPI continues geothermal and hydrogeological monitoring in several boreholes instrumented in 2014-2015 in District 203.
District 203 development model.
Subsurface conditions in District 203 in 2019 showing areas of
(1) active-layer water, (2) 10-15 m taliks, (3) 15-20 m taliks, (3) >20 m taliks, (5) borehole, (6) floodplain boundary.
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Pavlova N., Ogonerov V., Danzanova M., Popov V. (2020). Hydrogeology of reclaimed floodplain in a permafrost area, Yakutsk, Russia. Geosciences, 10 (5), art. no. 192, DOI: 10.3390/geosciences10050192
Zhang R.V., Pavlova N.A., Ogоnerov V.V., Lobanov A.L., Zabolotnik P.S., Danzanova M.V. (2020). Civil construction on low floodplains in permafrost region. In: Environmental and Infrastructure Integrity in Permafrost Regions: Proceedings of the Russian Conference with International Participation on the Occasion of the 60th Anniversary of the Melnikov Permafrost Institute, Yakutsk (Russia), September 28–30, 2020, pp. 440-444 [in Russian]