{{Short description|Construction technique}} thumb|Artificial ground freezing allowed tunnels to be excavated under an active railyard during Boston's Big Dig. Each white lump marks the top of a deep ground-freezing tap. thumb|Cross section of an artificial ground freezing pipe as used in the Big Dig. '''Artificial ground freezing''' is a construction technique used in circumstances where soil needs to be stabilized so it will not collapse next to excavations, or to prevent contaminants spilled into soil from being leached away.<ref name=PbsGroundFreezing/> Artificial ground freezing was used for the first time in 1862 in Swansea, South Wales, UK by Siebe Gorman & Co. The system was applied for a coal mine shaft sinking.<ref>{{Cite journal |last=Alzoubi |first=Mahmoud A. |last2=Xu |first2=Minghan |last3=Hassani |first3=Ferri P. |last4=Poncet |first4=Sébastien |last5=Sasmito |first5=Agus P. |date=2020-10-01 |title=Artificial ground freezing: A review of thermal and hydraulic aspects |url=https://www.sciencedirect.com/science/article/pii/S0886779820304880 |journal=Tunnelling and Underground Space Technology |volume=104 |article-number=103534 |doi=10.1016/j.tust.2020.103534 |issn=0886-7798|url-access=subscription }}</ref>
Pipes are run through the soil to be frozen, and then refrigerants are run through the pipes, freezing the soil.<ref name=PbsGroundFreezing/><ref>{{Cite journal |last=Alzoubi |first=Mahmoud A. |last2=Nie-Rouquette |first2=Aurelien |last3=Sasmito |first3=Agus P. |date=2018-11-01 |title=Conjugate heat transfer in artificial ground freezing using enthalpy-porosity method: Experiments and model validation |url=https://www.sciencedirect.com/science/article/pii/S0017931018311141 |journal=International Journal of Heat and Mass Transfer |volume=126 |pages=740–752 |doi=10.1016/j.ijheatmasstransfer.2018.05.059 |issn=0017-9310|url-access=subscription }}</ref>
== Design == Some artificial ground freezing projects use common salt brine as the refrigerant,<ref name=DotBigDig/> but other projects benefit from using more exotic refrigerants, like liquid nitrogen<ref name=PbsGroundFreezing/><ref name=Boc/> or solid carbon dioxide ('dry ice').<ref>{{cite journal |last1=Nikolaev |first1=Petr |last2=Sedighi |first2=Majid |last3=Rajabi |first3=Hamid |last4=Pankratenko |first4=Alexander |title=Artificial ground freezing by solid carbon dioxide – Analysis of thermal performance |journal=Tunnelling and Underground Space Technology |date=1 December 2022 |volume=130 |article-number=104741 |doi=10.1016/j.tust.2022.104741|doi-access=free }}</ref>
== Examples == Soil contaminated with radioactive elements that leaked from Japan's Fukushima Daiichi nuclear power plant was contained through artificial ground freezing.<ref name=PbsGroundFreezing/>
A project in Boston known as the Big Dig used artificial ground freezing during some of its tunneling, to allow its wide tunnels to be built under or through soil that supported existing infrastructure that would have been difficult or expensive to support using more traditional excavation methods.<ref name=PbsGroundFreezing/>
In northern Canada and arctic Alaska, passive pipe systems are used that do not require any external power to keep the ground frozen.<ref name=FlatLoop/> These systems use in-ground evaporators and above-ground radiators filled with liquid refrigerant. When ambient temperatures fall below ground temperatures, the liquid vapor starts condensing in the radiator, reducing the pressure in the system causing the liquid in the evaporator to boil and evaporate. This process results in heat transfer from the ground to the air and keeps the ground in a permanent frozen state.<ref name=Thermosyphon/>
Hani and Evirgen (2023) introduced a new method for sampling granular soils without disturbing their natural state; they suggest using artificial artificial ground freezing, a ground enhancement technique, as an on-site option for deep excavation applications.<ref>{{cite journal |last1=Hani |first1=Mostefa |last2=Evirgen |first2=Burak |title=A frozen soil sampling technique for granular soils and thermal modeling |journal=Bulletin of Engineering Geology and the Environment |date=2023 |volume=82 |issue=9 |page=354 |doi=10.1007/s10064-023-03372-4}}</ref>
==See also== * Pykrete, a composite building material which utilizes similar properties in frozen sawdust, Hani and Evirgen investigated the mechanical and microstructural properties of an artificially frozen sawdust-ice mixture (pykrete) and its usability as a retaining structure.<ref>{{cite journal |last1=Hani |first1=Mostefa |last2=Evirgen |first2=Burak |title=The Mechanical and Microstructural Properties of Artificially Frozen Sawdust–Ice Mixture (Pykrete) and Its Usability as a Retaining Structure |journal=International Journal of Civil Engineering |date=2023 |volume=21 |pages=119–134 |doi=10.1007/s40999-022-00751-y }}</ref> In addition, they developed an uncoupled thermo-hydro-mechanical approach to simulate a pykrete diaphragm wall for numerical analysis using finite element methods.<ref>{{cite journal |last1=Hani |first1=Mostefa |last2=Evirgen |first2=Burak |title=Uncoupled thermo-hydro-mechanical modeling of a pykrete diaphragm wall for an alternative artificial ground freezing application |journal=Computers and Geotechnics |date=2024 |volume=169 |article-number=106243 |doi=10.1016/j.compgeo.2024.106243}}</ref>
==References== {{Reflist| refs= <ref name=Boc> {{cite news | url = http://www.boc-gas.com.au/en/processes/water_and_soil_treatment/ground_freezing/index.html | title = Ground Freezing: Freezing soil with liquid nitrogen | publisher = The Linde Group | date = 2014 | archive-url = https://web.archive.org/web/20140226093544/http://www.boc-gas.com.au/en/processes/water_and_soil_treatment/ground_freezing/index.html | archive-date = 2014-02-26 | access-date = 2014-07-22 | url-status = live | quote = During the last two decades soil freezing with liquid nitrogen (LIN) has developed from an exotic gas application with many uncertainties into a standard procedure for treating unstable soil and leakages. }} </ref> <ref name=PbsGroundFreezing> {{cite news | url = https://www.pbs.org/wgbh/nova/article/artificial-ground-freezing/ | title = How Engineers Use Ground Freezing to Build Bigger, Safer, and Deeper | publisher = PBS | author = Jessica Morrison | date = 2013-10-30 | archive-url = https://web.archive.org/web/20140411143354/http://www.pbs.org/wgbh/nova/next/tech/artificial-ground-freezing/ | archive-date = 2014-04-11 | access-date = 2014-07-22 | url-status = live | quote = The basic premise behind ground freezing is that soil—made up of bits of minerals and organic matter, water, and air—becomes stronger and less penetrable when its water freezes and expands. }} </ref> <ref name=DotBigDig> {{cite news | url = https://www.fhwa.dot.gov/bridge/tunnel/ | title = Technical Manual for Design and Construction of Road Tunnels - Civil Elements | publisher = US Department of Transport | archive-url = https://web.archive.org/web/20131205014516/http://www.fhwa.dot.gov/Bridge/tunnel/pubs/nhi09010/12.cfm | archive-date = 2013-12-05 | access-date = 2014-07-22 | url-status = live | quote = In order to maintain support to the tunnel face, excavation and jacking normally carried out alternately in small increments, typically in the range of 2 to 4 feet. In most cases, the soft ground must be treated by means of ground improvement techniques such as ground freezing, jet grouting, etc. as discussed in Chapter 7 Soft Ground Tunneling to enhance its stand up time. }} </ref> <ref name=FlatLoop> {{cite news | url = http://www.pws.gov.nt.ca/pdf/publications/Thermosyphon%20Foundations%20in%20warm%20permafrost%20.pdf | title = Flat Loop Thermosyphon Foundations in Warm Permafrost | publisher = Government of the NT Asset Management Division Public Works and Services | author = Igor Holubec, Ph.D., P.Eng | date = 2014 | archive-url = https://web.archive.org/web/20150402092321/http://www.pws.gov.nt.ca/pdf/publications/Thermosyphon%20Foundations%20in%20warm%20permafrost%20.pdf | archive-date = 2015-04-02 | access-date = 2015-06-12 | url-status = live | quote = Passive cooling by means of pressured heat exchange pipes was developed in Alaska by the U.S. Army Corps of Engineers in 1965 to preserve foundations in 'warm' permafrost. }} </ref>
<ref name=Thermosyphon> {{cite news | url = http://simmakers.com/thermosyphon-technology-ground-freezing/ | title = Thermosyphon Technology for Ground Freezing | date = 2014 | archive-url = https://web.archive.org/web/20141126093213/http://simmakers.com/thermosyphon-technology-ground-freezing | archive-date = 2014-11-26 | access-date = 2015-06-12 | url-status = live | quote = The basis of thermosyphon thechnology is a heat transfer device (thermosyphon) which extracts the heat from the soil during winter and passes it to the environment. }} </ref> }}
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Category:Ground freezing