Artificial ground freezing is a technique that converts in situ pore water to ice through the circulation of a chilled liquid via a system of small-diameter pipes placed in drilled holes.
Artificial ground freezing for groundwater control and excavation support was developed more than a century ago. The technique is cost-effective in a relatively well-defined niche where both support of excavation and groundwater cut-off are required, and it is performed at significant depth or in difficult, disturbed, or sensitive ground.
The ground freezing process converts in situ pore water to ice through the circulation of a chilled liquid via a system of small-diameter pipes placed in drilled holes. The ice acts to fuse the soil or rock particles together, creating a frozen mass of improved compressive strength and impermeability. Brine is the typical cooling agent, although fast acting liquid nitrogen can be used for projects where the freeze only needs to be quickly established and maintained for a short period of time or in emergency situations.