Vibro replacement is an efficient ground improvement technique that constructs dense aggregate columns by utilizing a crane-suspended downhole vibrator, to reinforce all soils and densify granular soils. Vibro replacement stone columns are constructed with either the wet top feed process, or the dry bottom feed process.
The vibrator’s weight and vibrations along with water jets located in the vibrator’s tip allows the vibrator penetrate into the soil to achieve the design depth in the wet top feed process. The stone whether is crushed or recycled concrete is then introduced at the ground surface to the annular space around the vibrator created by the jetting water. The stone falls through the annular space to the vibrator tip, and fills the void created as the vibrator is lifted several feet. The vibrator is lowered to densify and displace the underlying stone. The vibro replacement process is repeated until a dense stone column is constructed to the ground surface.
The dry bottom feed process is smilar with a slight difference that no water jets are utilized the stone is fed to the vibrator tip through a feed pipe attached to the vibrator. Pre-drilling of dense strata at the column location may be required for the vibrator to penetrate to the design depth. Both methods of construction create a high modulus stone column that reinforces the treatment zone and densifies surrounding granular soils.
Vibro replacement stone columns have been used to increase bearing capacity, and decrease settlement and mitigate liquefaction potential for all types of planned structures including buildings, embankments, dams, tanks and towers.