ABSTRACT
The use of ground freezing to strengthen and impermeabilize soils goes back almost a century and a half. The benefits accrue from the change of water to ice. In general terms, freezing is accomplished by bringing a cold medium into contact with the soil for a sufficient length of time for the pore water to freeze. In practice, pipes are placed in a suitable pattern into the zone to be frozen. Each pipe is a double unit, a small pipe concentric within a larger one. Refrigerant is pumped through the inner pipe and returns through the annulus, cooling the soil with which the outer pipe is in contact. After ice forms at the contact zone, continuing operation of the system causes the frozen zone to grow, and then eventually to contact the frozen zones from adjacent pipes. Virtually all saturated soils through which water is flowing at a rate less than four inches per hour can be frozen.
