Deep Soil Mixing

Deep Soil Mixing is a soil improvement technology used to construct cutoff or retaining walls and to treat contaminated soils, in-situ. This is accomplished with a series of overlapping stabilized soil columns (typically 24 to 56 inches in diameter and greater than 40-feet in depth). The stabilized soil columns are formed by a series of mixing shafts (2 to 4), guided by a crane-supported set of leads. As the mixing shafts are advanced into the soil grout or slurry is pumped through the hollow stem of the shaft and injected into the soil at the tip. The auger flights and mixing blades on the shafts blend the soil with the grout or slurry in pugmill fashion. The mixing shafts are positioned to overlap one another and form a continuously mixed overlapping column. When the design depth is reached, the augers are withdrawn and the mixing process is repeated on the way to the surface. Left behind are stabilized DSM columns having the following properties: low permeability; improved bearing capacity, or shear strength; or immobilized contaminants that when reinforced, are able to withstand differential soil and hydrostatic loading).