The deep mixing soil improvement are commenly used for soft ground improvement and foundation systems for embankments, port and harbor foundations, retaining walls, and liquefaction mitigations. The advantage of this method is that it not only improves the strength of soft ground, but is a superior method for the prevention of settlement. Quality controls of the improved soils affect of the efficiency of this method are not yet properly established. These effects vary depending on the construction environments and operating conditions of the mixing paddle. The strength and shape of the improved column are not unique and these are affected by the mechanical properties of the mixing paddles.

In order to investigate the efficiency of the deep mixing soil improvement on a soft clay, experimental studies are conducted that consider the mechanical properties of mixing paddles; the location of the exit-hole of the admixtures, the angle of the mixing wing. The experiments are conducted with a simulated deep mixing plant at a reduced scale of 1:8 of the real plant. From the results, the sizes and shape of the improved column mass vary depending on the mechanical properties and operating conditions of the mixing paddle. The quality of the column in the shapes and strength is improved when the exit-hole for admixtures is located in the mixing wing, when an angle of the mixing wing is large.