The compaction of loose soils or uncompacted fills can be achieved at depth by using the process of vibroflotation.

The penetration of the vibroflot in granular soils produces a cavity that is subsequently filled with gravel, either feed from the top of the hole or using a bottom feed system. The vibroflot is then reintroduced into the gravel and the procedure repeated until adequate stone compaction and column size has been achieved.

Each vibrocompaction phase is carried out in 300 to 500 mm steps, proceeding from the bottom to the top so as to create a "stone column" with load bearing properties and vertical drainage effects.

Case history at "CHALON SUR SAONE"

The construction of an industrial plant with various storage areas for a total surface area of 10,000 m2 at Chalon sur Saone (France) was performed by Menard using stone columns in silt deposits.
The soil reinforcement consisted of a network of 1700 columns installed by the bottom feed method to a depth of 8 m in a triangular pattern at 2.7 m centers.