Vibro Compaction is a proven method for densifying granular soils with less than 10 – 15% silt present.
The process is done ‘in situ’, using an electric or hydraulic driven vibratory unit known as a Vibroflot.
Under the influence of simultaneous vibration and saturation, loose sand and / or gravel particles are repacked into a denser state and hence the lateral confining pressure within the soil mass is increased.
As an option, additional extension tubes can be added to allow the Vibroflot to do its work to depths in excess of 30 meters below surface level.
Phase 1: Penetration
With the aid of air and/or water pressure at the nose cone, to assist with penetration, the Vibroflot is lowered steadily into the ground to a predetermined design depth. At the same time, the side jets are also working with a air/water mixture to agitate the sand, remove any fines and assist to form an annular gap around the Vibroflot.
Upon reaching the correct design depth, the air/water at the nose cone, is either reduced or switched off.
Phase 2: Compaction
Due to induced horizontal forces, the soil particles surrounding the tip of the Vibroflot are rearranged to a denser state of compaction.
The Vibroflot is raised incrementally as compaction is achieved.
During this compaction phase, either in situ (1) or imported (2) material is pushed into the void around the Vibroflot. In case only the in situ material is used, the surface or the area being compacted will be lowered.
Once the compaction process has been completed, the ground is levelled and then a surface compactor is required to densify the top layer of around 2mtr in depth.
Typical Compaction Grid Layout