Vibro compaction improves and densifies granular, cohesionless soils to depths up to 35 m using a proprietary down-hole vibrator.
- Improve bearing capacity
- Reduce settlement
- Reduce liquefaction potential
The vibrator used for the vibro-compaction process is usually suspended by a crane and use its own weight and vibrations to advance vertically into the soil to the target depth. The vibrator assembly can also include water jets which helps with ground penetration. Densification of the soils occurs in lifts as the vibrator is removed from the bottom of the treatment zone. It is the vibratory energy that allows soil particles to move into a denser configuration, usually reaching a relative density of 70 to 85%. Meanwhile, at ground surface, clean sand backfill is added to offset the soil volume loss during the densification process. This ensures the elevation of the original site is preserved. In cases where the planned final site elevation is lower than the existing, lowering of the ground surface during densification is possible.
Generally, when designing a vibro-compaction project, spacing between penetrations locations is between 2 and 4 m; the centres of which are on a triangular or square pattern. Permanent densification is achieved because vibro-compaction occurs without the use of internal stresses in the soil. The improved characteristics of the soil is contingent on soil type and gradation, penetration location spacing, and time spent during compaction.