Deep Soil Mixing (DSM) is a ground improvement technique that involves the blending of a hardening agent (usually cement grout) with the native soils, in situ. The process improves the strength and stiffness of the native soil.
A revolving hollow shaft with mixing paddles and/or a section of auger (the mixing tool) is advanced into the soil. As the mixing tool is advanced, the cement grout is pumped through the hollow stem of the revolving shaft and discharged laterally along the lower mixing paddle where it is mixed with the native soil. The kneading action of the mixing tool blends the cement grout and the soil. When the design depth is reached, the tool is withdrawn while maintaining, or often increasing, the rotational speed of the mixing tool. The resulting column is a well-blended mixture of native soil and cement grout which will cure over time to the required design strength. Tie-down rebar can also be installed in the Soil Cement column to provide uplift capacity.