Soil Stabilization by Ground Freezing

Installation: Copper freeze pipes with a standard diameter of 2” (54 mm) are installed, at an average distance of 2” (54 mm) On the inside, downpipes with diameters of ½” (10–12) mm are installed.

Freezing: LIN is fed into the pipes through insulated supply lines. The LIN vaporizes, with 1 kg of LIN extracting about 200 kJ of energy from the surrounding soil, cooling and freezing it. The vaporized cold nitrogen (i.e., exhaust gas) extracts another 100 kJ from the ground. After about one week, this process forms a frozen wall with a diameter of about 1 m. This so-called “establishing phase” lasts four to seven days, and about 300 - 500 gal (1,500–2,500 l) of LIN is used to freeze 1 cubic yard (0.75 m³) of soil.

Maintenance: In the subsequent maintenance phase, the LIN supply is reduced. The frozen soil stops expanding and maintains its volume. Maintaining 1 cubic yard of frozen soil requires about 20 gal (70 l)

• Investments in a LIN freezing plant are only a fraction of those to install a brine freezing unit.
• The temperature of the frozen soil is substantially lower (and its stability therefore higher) than with a brine freezing plant.
• LIN’s low temperature -320°F (–196°C) allows soil-freezing in four to seven days – substantially quicker than the one month required by the brine freezing process.
• The process is environmental friendly, with no hazardous substances, vibrations, or ground water pollution or extraction.
• The process is suitable for automation.
• The process offers a combination of sealing and static support.
• Systems have a high tolerance to soil humidity (5–100%); frozen soil is 100% watertight, and there is no leakage.
• The hardness of frozen soil is comparable to concrete.
• The solidification of the soil is only temporary; after shutting down the LIN supply, frozen soil will melt in a few weeks.