Editing Permafrost (section)

=== Construction on permafrost ===

There are only two large cities in the world built in areas of continuous permafrost (where the frozen soil forms an unbroken, below-zero sheet) and both are in Russia – [[Norilsk]] in [[Krasnoyarsk Krai]] and [[Yakutsk]] in the [[Sakha Republic]].<ref name="NY11022">{{cite magazine|author1=Joshua Yaffa|date=January 20, 2022|title=The Great Siberian Thaw|magazine=The New Yorker|url=https://www.newyorker.com/magazine/2022/01/17/the-great-siberian-thaw|access-date=January 20, 2022}}</ref> Building on permafrost is difficult because the heat of the building (or [[pipeline transport|pipeline]]) can spread to the soil, thawing it. As ice content turns to water, the ground's ability to provide structural support is weakened, until the building is destabilized. For instance, during the construction of the [[Trans-Siberian Railway]], a [[steam engine]] factory complex built in 1901 began to crumble within a month of operations for these reasons.<ref name="Chu2020" />{{rp|47}} Additionally, there is no [[groundwater]] available in an area underlain with permafrost. Any substantial settlement or installation needs to make some alternative arrangement to obtain water.<ref name="NY11022" /><ref name="Chu2020" />{{rp|25}}

A common solution is placing [[foundation (architecture)|foundations]] on wood [[Deep foundation|piles]], a technique pioneered by Soviet engineer [[Mikhail Kim]] in Norilsk.<ref>{{Cite magazine|last=Yaffa|first=Joshua|date=2022-01-07|title=The Great Siberian Thaw|url=https://www.newyorker.com/magazine/2022/01/17/the-great-siberian-thaw|access-date=2022-01-12|magazine=The New Yorker }}</ref> However, warming-induced change of [[friction]] on the piles can still cause movement through [[Creep (deformation)|creep]], even as the soil remains frozen.<ref>{{Cite book|last=Fang|first=Hsai-Yang|url=https://books.google.com/books?id=X8hEt3l1SPQC&q=foundations+on+permafrost&pg=PA735|title=Foundation Engineering Handbook|date=1990-12-31|publisher=Springer Science & Business Media|isbn=978-0-412-98891-2|page=735 }}</ref> The [[Melnikov Permafrost Institute]] in Yakutsk found that pile foundations should extend down to {{convert|15|m}} to avoid the risk of buildings sinking. At this depth the temperature does not change with the seasons, remaining at about {{convert|-5|C}}.<ref>{{Cite book|last1=Sanger|first1=Frederick J.|url=https://books.google.com/books?id=YDArAAAAYAAJ&q=yakutsk+pile+foundations+on+permafrost&pg=PA786|title=Permafrost: Second International Conference, July 13–28, 1973 : USSR Contribution|last2=Hyde|first2=Peter J.|date=1978-01-01|publisher=National Academies|isbn=978-0-309-02746-5|page=786 }}</ref>

Two other approaches are building on an extensive [[gravel]] pad (usually {{cvt|1-2|m}} thick); or using [[anhydrous ammonia]] [[heat pipe]]s.<ref name="ASCE">{{cite book |last=Clarke |first=Edwin S. |title=Permafrost Foundations—State of the Practice |series=Monograph Series |publisher=American Society of Civil Engineers |year=2007 |url=https://books.google.com/books?id=O-voTug5apsC&pg=PA34 |isbn=978-0-7844-0947-3}}</ref> The [[Trans-Alaska Pipeline System]] uses [[Heat pipe#Permafrost cooling|heat pipes built into vertical supports]] to prevent the pipeline from sinking and the [[Qingzang railway]] in Tibet employs a variety of methods to keep the ground cool, both in areas with [[Frost heaving#Frost-susceptible soils|frost-susceptible soil]]. Permafrost may necessitate special enclosures for buried utilities, called "[[Utility tunnel#In Arctic towns|utilidors]]".<ref>{{Cite book|last=Woods|first=Kenneth B.|url=https://books.google.com/books?id=3jErAAAAYAAJ&q=utilidors+in+permafrost&pg=PA441|title=Permafrost International Conference: Proceedings|date=1966|publisher=National Academies|pages=418–57 }}</ref>

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<gallery mode="packed" heights="150px">
File:PICT4417Sykhus.JPG|A building on elevated piles in permafrost zone.
File:Trans-Alaska Pipeline (1).jpg|[[Heat pipe#Permafrost cooling|Heat pipes in vertical supports]] maintain a frozen bulb around portions of the [[Trans-Alaska Pipeline]] that are at risk of thawing.<ref>{{Cite web |url=http://apps.dtic.mil/dtic/tr/fulltext/u2/a073597.pdf |title=C. E. Heuer, "The Application of Heat Pipes on the Trans-Alaska Pipeline" Special Report 79-26, United States Army Corps of Engineers, Sept. 1979. |access-date=2013-10-22 |archive-date=2013-10-22 |archive-url=https://web.archive.org/web/20131022022419/http://www.dtic.mil/dtic/tr/fulltext/u2/a073597.pdf |url-status=live }}</ref>
File:Yakoutsk Construction d'immeuble.jpg|Pile foundations in [[Yakutsk]], a city underlain with continuous permafrost.
File:Raised pipes in permafrost.jpg|[[District heating]] pipes run above ground in Yakutsk.
</gallery>