Ground Freezing
Ground Freezing has been carried for groundwater control and excavation support. Two different techniques are used: the open method, which uses liquid nitrogen, and the closed method, where electric plants chill a solution of calcium chloride into the water (brine). Liquid nitrogen evaporates at a temperature of -196 °C, producing a thermic shock on the surrounding groundwater and freezing a cylinder of 1.00 m within 3 to 4 days. Brine circulates into steel pipes at a temperature of approximately -36°C, creating the same cylinder of frozen soil within 3 to 4 weeks.