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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.
Ground freezing has been used for at least one hundred years.
Pipes are run through the soil to be frozen, and then refrigerants are run through the pipes, freezing the soil.
Frozen soil can be as hard as concrete.
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.
Ground freezing has been used for at least one hundred years.
Pipes are run through the soil to be frozen, and then refrigerants are run through the pipes, freezing the soil.
Frozen soil can be as hard as concrete.
Design
Some ground freezing projects use common salt brine as the refrigerant, but other projects benefit from using more exotic refrigerants, likeliquid nitrogen
Liquid nitrogen (LN2) is nitrogen in a liquid state at cryogenics, low temperature. Liquid nitrogen has a boiling point of about . It is produced industrially by fractional distillation of liquid air. It is a colorless, mobile liquid whose vis ...
. or solid carbon dioxide ('dry ice').
Examples
Soil contaminated with radioactive elements that leaked fromJapan
Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...
's Fukushima Daiichi nuclear power plant was contained through ground freezing.
A project in Boston
Boston is the capital and most populous city in the Commonwealth (U.S. state), Commonwealth of Massachusetts in the United States. The city serves as the cultural and Financial centre, financial center of New England, a region of the Northeas ...
known as the Big Dig used 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.
In northern Canada and arctic Alaska, passive pipe systems are used that do not require any external power to keep the ground frozen. 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.
Hani and Evirgen (2023) introduced a new method for sampling granular soils without disturbing their natural state; they suggest using artificial ground freezing, a ground enhancement technique, as an on-site option for deep excavation applications.
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. In addition, they developed an uncoupled thermo-hydro-mechanical approach to simulate a pykrete diaphragm wall for numerical analysis using finite element methods.References
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