Proper soil mixing is an essential step in creating durable earth-retention solutions. When done correctly, the mixing process yields a soilcrete mixture that has both increased strength and reduced permeability.
One application for soil mixing is in the construction of earth-retaining structures where a groundwater cut-off is also required. Schnabel typically drills a series of overlapping soilcrete columns to create a continuous groundwater cutoff wall.
Steel piles are typically placed in the soilcrete while it is still wet to improve its strength. The increased strength of the treated ground allows it to span between the piles. The reduced permeability of a soil mix wall allows the excavation to take place under relatively dry conditions with limited draw down of the water table outside the excavation.
Soil mixing can also be used to create an impermeable barrier below the ground surface where no excavation takes place, such as to reduce seepage through a dam or to contain contaminated groundwater. Another use for soil mixing is the improvement of foundation soils to increase their strength and reduce the likelihood of liquefaction during an earthquake.