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Frost heaving (or a frost heave) is an upwards swelling of
soil Soil, also commonly referred to as earth or dirt, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Some scientific definitions distinguish ''dirt'' from ''soil'' by restricting the former ...
during freezing conditions caused by an increasing presence of ice as it grows towards the surface, upwards from the depth in the soil where
freezing Freezing is a phase transition where a liquid turns into a solid when its temperature is lowered below its freezing point. In accordance with the internationally established definition, freezing means the solidification phase change of a liquid ...
temperatures have penetrated into the soil (the freezing front or freezing boundary). Ice growth requires a water supply that delivers water to the freezing front via
capillary action Capillary action (sometimes called capillarity, capillary motion, capillary rise, capillary effect, or wicking) is the process of a liquid flowing in a narrow space without the assistance of, or even in opposition to, any external forces li ...
in certain soils. The weight of overlying soil restrains vertical growth of the ice and can promote the formation of lens-shaped areas of ice within the soil. Yet the force of one or more growing ice lenses is sufficient to lift a layer of soil, as much as or more. The soil through which water passes to feed the formation of ice lenses must be sufficiently porous to allow capillary action, yet not so porous as to break capillary continuity. Such soil is referred to as "frost susceptible". The growth of ice lenses continually consumes the rising water at the freezing front. Differential frost heaving can crack road surfaces—contributing to springtime
pothole A pothole is a depression in a road surface, usually asphalt pavement, where traffic has removed broken pieces of the pavement. It is usually the result of water in the underlying soil structure and traffic passing over the affected area. Wate ...
formation—and damage building foundations. Frost heaves may occur in mechanically refrigerated cold-storage buildings and
ice rink An ice rink (or ice skating rink) is a frozen body of water and/or an artificial sheet of ice created using hardened chemicals where people can ice skate or play winter sports. Ice rinks are also used for exhibitions, contests and ice shows. The ...
s. Needle ice is essentially frost heaving that occurs at the beginning of the freezing season, before the freezing front has penetrated very far into the soil and there is no soil overburden to lift as a frost heave.


Mechanisms


Historical understanding of frost heaving

Urban Hjärne Urban Hjärne (20 December 1641 – 10 March 1724) was a Swedish chemist, geologist, physician and writer. Biography He was born at Skworitz near Nyenschantz in Swedish Ingria. He was the son of vicar Erlandus Jonæ Hiærne (1596–1654 ...
described frost effects in soil in 1694. By 1930, Stephen Taber, head of the Department of Geology at the University of South Carolina, had disproved the hypothesis that frost heaving results from molar volume expansion with freezing of
water Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as ...
already present in the soil prior to the onset of subzero temperatures, i.e. with little contribution from the migration of water within the soil. Since the molar volume of water expands by about 9% as it changes phase from water to ice at its bulk
freezing point The melting point (or, rarely, liquefaction point) of a substance is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depend ...
, 9% would be the maximum expansion possible owing to molar volume expansion, and even then only if the ice were rigidly constrained laterally in the soil so that the entire volume expansion had to occur vertically. Ice is unusual among compounds because it increases in molar volume from its liquid state,
water Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as ...
. Most compounds decrease in volume when changing phase from liquid to solid. Taber showed that the vertical displacement of soil in frost heaving could be significantly greater than that due to molar volume expansion. Taber demonstrated that liquid water migrates towards the freeze line within soil. He showed that other liquids, such as
benzene Benzene is an organic chemical compound with the molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar ring with one hydrogen atom attached to each. Because it contains only carbon and hydrogen atoms ...
, which contracts when it freezes, also produce frost heave. This excluded molar volume changes as the dominant mechanism for vertical displacement of freezing soil. His experiments further demonstrated the development of
ice lens Ice lenses are bodies of ice formed when moisture, diffused within soil or rock, accumulates in a localized zone. The ice initially accumulates within small collocated pores or pre-existing crack, and, as long as the conditions remain favorable ...
es inside columns of soil that were frozen by cooling the upper surface only, thereby establishing a
temperature gradient A temperature gradient is a physical quantity that describes in which direction and at what rate the temperature changes the most rapidly around a particular location. The temperature gradient is a dimensional quantity expressed in units of degre ...
.


Development of ice lenses

The dominant cause of soil displacement in frost heaving is the development of ice lenses. During frost heave, one or more soil-free ice lenses grow, and their growth displaces the soil above them. These lenses grow by the continual addition of water from a groundwater source that is lower in the soil and below the freezing line in the soil. The presence of frost-susceptible soil with a pore structure that allows capillary flow is essential to supplying water to the ice lenses as they form. Owing to the Gibbs–Thomson effect of the confinement of liquids in pores, water in soil can remain liquid at a temperature that is below the bulk freezing point of water. Very fine pores have a very high
curvature In mathematics, curvature is any of several strongly related concepts in geometry. Intuitively, the curvature is the amount by which a curve deviates from being a straight line, or a surface deviates from being a plane. For curves, the can ...
, and this results in the
liquid A liquid is a nearly incompressible fluid that conforms to the shape of its container but retains a (nearly) constant volume independent of pressure. As such, it is one of the four fundamental states of matter (the others being solid, gas, ...
phase being
thermodynamically stable In chemistry, chemical stability is the thermodynamic stability of a chemical system. Thermodynamic stability occurs when a system is in its lowest energy state, or in chemical equilibrium with its environment. This may be a dynamic equilibriu ...
in such media at temperatures sometimes several tens of degrees below the bulk freezing point of the liquid. This effect allows water to percolate through the soil towards the ice lens, allowing the lens to grow. Another water-transport effect is the preservation of a few
molecular A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions which satisfy this criterion. In quantum physics, organic chemistry, and bio ...
layers of liquid water on the surface of the ice lens, and between ice and soil particles. Faraday reported in 1860 on the unfrozen layer of premelted water. Ice premelts against its own
vapor In physics, a vapor (American English) or vapour (British English and Canadian English; see spelling differences) is a substance in the gas phase at a temperature lower than its critical temperature,R. H. Petrucci, W. S. Harwood, and F. G. Her ...
, and in contact with
silica Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , most commonly found in nature as quartz and in various living organisms. In many parts of the world, silica is the major constituent of sand. Silica is ...
.


Micro-scale processes

The same intermolecular forces that cause premelting at surfaces contribute to frost heaving at the particle scale on the bottom side of the forming ice lens. When ice surrounds a fine soil particle as it premelts, the soil particle will be displaced downward towards the warm direction within the thermal gradient due to melting and refreezing of the thin film of water that surrounds the particle. The thickness of such a film is temperature dependent and is thinner on the colder side of the particle. Water has a lower
thermodynamic free energy The thermodynamic free energy is a concept useful in the thermodynamics of chemical or thermal processes in engineering and science. The change in the free energy is the maximum amount of work that a thermodynamic system can perform in a process ...
when in bulk ice than when in the supercooled liquid state. Therefore, there is a continuous replenishment of water flowing from the warm side to the cold side of the particle, and continuous melting to re-establish the thicker film on the warm side. The particle migrates downwards toward the warmer soil in a process that Faraday called "thermal regelation." This effect purifies the ice lenses as they form by repelling fine soil particles. Thus a 10-
nanometer 330px, Different lengths as in respect to the molecular scale. The nanometre (international spelling as used by the International Bureau of Weights and Measures; SI symbol: nm) or nanometer (American and British English spelling differences#-re, ...
film of unfrozen water around each
micrometer Micrometer can mean: * Micrometer (device), used for accurate measurements by means of a calibrated screw * American spelling of micrometre The micrometre ( international spelling as used by the International Bureau of Weights and Measures; ...
-sized soil particle can move it 10 micrometers/day in a thermal gradient of as low as 1 °C m−1. As ice lenses grow, they lift the soil above, and segregate soil particles below, while drawing water to the freezing face of the ice lens via capillary action.


Frost-susceptible soils

Frost heaving requires a frost-susceptible soil, a continual supply of water below (a
water table The water table is the upper surface of the zone of saturation. The zone of saturation is where the pores and fractures of the ground are saturated with water. It can also be simply explained as the depth below which the ground is saturated. T ...
) and freezing temperatures, penetrating into the soil. Frost-susceptible soils are those with pore sizes between particles and particle surface area that promote capillary flow. Silty and loamy
soil types A soil type is a taxonomic unit in soil science. All soils that share a certain set of well-defined properties form a distinctive soil type. Soil type is a technical term of soil classification, the science that deals with the systematic categoriz ...
, which contain fine particles, are examples of frost-susceptible soils. Many agencies classify materials as being frost susceptible if 10 percent or more constituent particles pass through a 0.075 mm (No. 200) sieve or 3 percent or more pass through a 0.02 mm (No. 635) sieve. Chamberlain reported other, more direct methods for measuring frost susceptibility. Based on such research, standard tests exist to determine the relative frost and thaw weakening susceptibility of soils used in pavement systems by comparing the heave rate and thawed bearing ratio with values in an established classification system for soils where frost-susceptibility is uncertain. Non-frost-susceptible soils may be too dense to promote water flow (low hydraulic conductivity) or too open in porosity to promote capillary flow. Examples include dense
clay Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4). Clays develop plasticity when wet, due to a molecular film of water surrounding the clay pa ...
s with a small pore size and therefore a low hydraulic conductivity and clean
sand Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural class ...
s and
gravel Gravel is a loose aggregation of rock fragments. Gravel occurs naturally throughout the world as a result of sedimentary and erosive geologic processes; it is also produced in large quantities commercially as crushed stone. Gravel is classifi ...
s, which contain small amounts of fine particles and whose pore sizes are too open to promote capillary flow.


Landforms created by frost heaving

Frost heaving creates raised-soil landforms in various geometries, including circles, polygons and stripes, which may be described as palsas in soils that are rich in organic matter, such as peat, or lithalsa in more mineral-rich soils. The stony lithalsa (heaved mounds) found on the archipelago of
Svalbard Svalbard ( , ), also known as Spitsbergen, or Spitzbergen, is a Norwegian archipelago in the Arctic Ocean. North of mainland Europe, it is about midway between the northern coast of Norway and the North Pole. The islands of the group rang ...
are an example. Frost heaves occur in alpine regions, even near the
equator The equator is a circle of latitude, about in circumference, that divides Earth into the Northern and Southern hemispheres. It is an imaginary line located at 0 degrees latitude, halfway between the North and South poles. The term can also ...
, as illustrated by palsas on
Mount Kenya Mount Kenya (Kikuyu language, Kikuyu: ''Kĩrĩnyaga'', Kamba language, Kamba, ''Ki Nyaa'') is the highest mountain in Kenya and the Highest mountain peaks of Africa, second-highest in Africa, after Mount Kilimanjaro, Kilimanjaro. The highest pea ...
. In
Arctic The Arctic ( or ) is a polar regions of Earth, polar region located at the northernmost part of Earth. The Arctic consists of the Arctic Ocean, adjacent seas, and parts of Canada (Yukon, Northwest Territories, Nunavut), Danish Realm (Greenla ...
permafrost Permafrost is ground that continuously remains below 0 °C (32 °F) for two or more years, located on land or under the ocean. Most common in the Northern Hemisphere, around 15% of the Northern Hemisphere or 11% of the global surface ...
regions, a related type of ground heaving over hundreds of years can create structures, as high as 60 metres, known as pingos, which are fed by an upwelling of ground water, instead of the capillary action that feeds the growth of frost heaves.
Cryogenic In physics, cryogenics is the production and behaviour of materials at very low temperatures. The 13th IIR International Congress of Refrigeration (held in Washington DC in 1971) endorsed a universal definition of “cryogenics” and “cr ...
earth
hummocks In geology, a hummock is a small knoll or mound above ground.Bates, Robert L. and Julia A. Jackson, ed. (1984). “hummock.” Dictionary of Geological Terms, 3rd Ed. New York: Anchor Books. p. 241. They are typically less than in height and ...
are a small formation resulting from
granular convection Granular convection is a phenomenon where granular material subjected to shaking or vibration will exhibit circulation patterns similar to types of fluid convection. It is sometimes called the Brazil nut effect, when the largest of irregularly sh ...
that appear in seasonally frozen ground and have many different names; in North America they are earth hummocks; thúfur in
Greenland Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an island country in North America that is part of the Kingdom of Denmark. It is located between the Arctic and Atlantic oceans, east of the Canadian Arctic Archipelago. Greenland ...
and
Iceland Iceland ( is, Ísland; ) is a Nordic island country in the North Atlantic Ocean and in the Arctic Ocean. Iceland is the most sparsely populated country in Europe. Iceland's capital and largest city is Reykjavík, which (along with its ...
; and pounus in
Fennoscandia __NOTOC__ Fennoscandia ( Finnish, Swedish and no, Fennoskandia, nocat=1; russian: Фенноскандия, Fennoskandiya) or the Fennoscandian Peninsula is the geographical peninsula in Europe, which includes the Scandinavian and Kola penin ...
. Polygonal forms apparently caused by frost heave have been observed in near-polar regions of Mars by the Mars Orbiter Camera (MOC) aboard the
Mars Global Surveyor ''Mars Global Surveyor'' (MGS) was an American robotic space probe developed by NASA's Jet Propulsion Laboratory and launched November 1996. MGS was a global mapping mission that examined the entire planet, from the ionosphere down through t ...
and the
HiRISE High Resolution Imaging Science Experiment is a camera on board the '' Mars Reconnaissance Orbiter'' which has been orbiting and studying Mars since 2006. The 65 kg (143 lb), US$40 million instrument was built under the direction ...
camera on the
Mars Reconnaissance Orbiter ''Mars Reconnaissance Orbiter'' (MRO) is a spacecraft designed to study the geology and climate of Mars, provide reconnaissance of future landing sites, and relay data from surface missions back to Earth. It was launched on August 12, 2005, an ...
. In May 2008 the
Mars Phoenix ''Phoenix'' was an uncrewed space probe that landed on the surface of Mars on May 25, 2008, and operated until November 2, 2008. ''Phoenix'' was operational on Mars for sols ( days). Its instruments were used to assess the local habitabilit ...
lander touched down on such a polygonal frost-heave landscape and quickly discovered ice a few centimetres below the surface.


In refrigerated buildings

Cold-storage buildings and ice rinks that are maintained at sub-freezing temperatures may freeze the soil below their foundations to a depth of tens of meters. Seasonally frozen buildings, e.g. some ice rinks, may allow the soil to thaw and recover when the building interior is warmed. If a refrigerated building's foundation is placed on frost-susceptible soils with a water table within reach of the freezing front, then the floors of such structures may heave, due to the same mechanisms found in nature. Such structures may be designed to avoid such problems by employing several strategies, separately or in tandem. The strategies include placement of non-frost-susceptible soil beneath the foundation, adding insulation to diminish the penetration of the freezing front, and heating the soil beneath the building sufficiently to keep it from freezing. Seasonally operated ice rinks can mitigate the rate of subsurface freezing by raising the temperature of the ice.


See also

*
Cryoturbation In gelisols ( permafrost soils), cryoturbation (frost churning) refers to the mixing of materials from various horizons of the soil down to the bedrock due to freezing and thawing. Cryoturbation occurs to varying degrees in most gelisols. The c ...
* Frost law * Frost weathering * Ice jacking * Palsa


Footnotes


References


Further reading

* {{DEFAULTSORT:Frost Heaving Building defects Geomorphology Glaciology Ground freezing Patterned grounds Soil mechanics Frost and rime