The basic principle of ground freezing is the use of a heat transfer fluid to stabilize the ground. A cold medium is circulated through a suitable pipe system, which cools the soil and thus converts the in-situ water to ice. It is used for major ground works in soil conditions which are not very stable. The use of ground freezing will prevent flowing downhill of water and mud, which can cause enormous problems in tunneling projects.
Our recommended product is
Freezium
-60°C or
Zitrec S -55°C
Ground freezing is not a new technology. It has been applied in Europe and North America for more than a century in cases of temporary ground freezing on a variety of construction and mining projects, for groundwater control and for excavation support in the underground construction industry.
Application areas
Although ground freezing has been
used for many years primarily on large complex projects where groundwater
and caving soils create an unstable situation and ground freezing represents
the only possible solution, today ground freezing applications are also
being promoted in the civil engineering arena. The reason for this switch is the use of smaller
pipes and smaller refrigeration equipments, of which the design can be
modified to freeze quickly or if needed, slower at less cost if time
permits. Together with its soil stabilizing capability to bear stress, the
ability to block water flow and its cost-effectiveness in achieving a
desired result, ground freezing is very effective for shoring in wet loose
soils.
The process
Ground freezing involves the
circulation of a cold medium through a suitable pipe system, which cools the
soil and thus converts soil water to ice. As cold medium mostly brines
are used.
When wet soil freezes, the main process is the physical change of soil water from liquid to solid that turns the soil into a hard mass resembling concrete. The rate at which soil freezes is dependent upon its thermal properties, moisture content, and the ambient air temperature. Of these, probably the most important is the amount of water to be frozen.
Advantages of ground freezing :
There are many advantages of ground freezing:
Ground freezing can be applied in all types of soil and groundwater conditions, such as running sand, clay, gravel... , and allows to work in each of these soils.
Ground freezing is most effective as an earth support system where groundwater is a concern and where either pumping or cutting off the water flow cannot be readily achieved with other methods. Ground freezing can provide absolute water cut off and can be installed in difficult ground conditions.
Ground freezing can be used for either temporary containment, such as to prevent offsite migration, or either as a long term barrier.
Ground freezing can be removed easily and completely, simply by allowing the ground to thaw naturally. It has no long-term effect on the subsurface environment.
Ground freezing allows the frozen soil barriers to be easily monitored in many ways just by including temperature and pressure sensors.
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