Artificial Ground Freezing

Artificial ground freezing technique is used to construct substructures in soft, unstable water-bearing soils.
The essence of this technique lies in drilling a system of boreholes with freezing pipes every 0.8-2m prior to starting operations along the substructure contour. Coolant liquid cooled to subfreezing temperatures (-20 -40) QC is passed through freezing pipes using pumps.
Due to constant circulation of coolant in freezing pipes, the water in water-saturated ground freezes and ice wall cylinders are formed around each pipe, which are later joined into a solid ice wall (Figure 1).
Frozen grounds abruptly change their physical and mechanical properties (strength, adhesion etc.), which allows starting mining operations after the design dimensions are reached. In that case, the ice wall serves as temporary waterproof lining, which ensures safe conditions for mining and construction works.

Ice wall is kept in frozen condition until the construction of substructure is completed. After the substructure construction is finished the ice wall is removed.

• In metro engineering : construction of  escalator tunnels;
• In hydraulic engineering the freezing method is used to excavate pits for dam construction, power plant buildings, dockage facilities and other structures;
• In industrial engineering this method is applied to construct foundations for machines and industrial buildings;
• Construction of subsurface structures for water supply, underground crusher stations at processing plants, etc.;
• Construction of miscellaneous tunnels in unstable formations;
• Construction of mines;
• Construction of underground petroleum gases storage tanks;
• Keeping storage facility walls in frozen condition

Freezing of formations includes following stages:

• well drilling;
• installation of freezing pipes and brine network;
• construction of ice wall with required dimensions (active freezing).

Following drilling rigs are used for well drilling:

• Drillmec G-25 (Italy)
• Drillmec G-33 Astra (Italy)
• Drillmec G-33 Iveco (Italy)

• Belaruskali OJSC in Soligorsk
• Mining and processing plant at Garlyk potash deposit in Lebap Region, Turkmenistan
• Petrikovsky mining and processing plant, Petrikov