Vibro Compaction

Vibro Compaction is the process of densifying clean loose sands with specialty down the hole Vibro-Probes.

Typically, Vibro-Probes are hung from a crane and penetrate to the treatment depth under their own weight, vibratory force and water jetting.

The densification process is performed from the bottom upward in two to three foot intervals. As the in-situ sands densify, clean sand is added at the surface to facilitate compaction and keep the site grade level.


  • Vibro Compaction should only be used on sites in which clean sands with less than 10 to 12 percent silt and no clay is present
  • Low to mid rise new construction buildings
  • Area loads such as tanks and embankments
  • Seismic mitigation beneath any structure or embankment
  • Densification of large areas of clean sand fill, such as dredge sites or lake filling
  • Sinkhole triggering and collapsing

Construction Advantages

  • Very economical compared to deep foundation systems
  • Increased allowable soil bearing capacity reduces the size of foundations
  • Expedient process and minimal site disturbance

What to Expect

  • Earth Tech will provide a signed and sealed design indicating the treatment plan
  • Site clearing and access preparation precede Vibro Compaction
  • 2” water source may be required for jetting the Vibro-Probe
  • Sand backfill is required and usually on-site sand is utilized
  • Generally this work is performed under a performance specification, with minimum improvement criteria specified
  • Post treatment testing, using SPT’s or CPT’s is used to verify specified requirements
  • Plate load testing can also be utilized to verify bearing capacity and settlement requirements
  • Final site grading and foundation construction follows Vibro Compaction