Dynamic Compaction is an in-situ compaction technique that has been successfully used by FRANKI in projects throughout Southern Africa.  The technique involves the in-situ compaction of soils to depths of up to 12m using pounders to impart high energy compaction.  The choice of pounder and drop height depends on site conditions, compaction depths and materials to be compacted.  Available pounders vary in mass from 7 to 15 tonnes.  Using high capacity crawler mounted cranes, the pounders are dropped from heights of up to 22m to achieve the desired compaction depth.

Dynamic Consolidation is normally used under the following circumstances:

  • To increase in-situ density and in this way improve the bearing capacity and consolidation characteristics of soils (or waste materials) to allow conventional foundation and surface bed construction to be carried out. 
  • To increase in-situ density and in this way improve in-situ permeability and / or reduce liquefaction potential.

Not all material types are suitable for Dynamic Consolidation.  Under these circumstances Dynamic Replacement can often be utilised. In this technique a selected material is driven to partially or completely displace the unsuitable in-situ material to form columns of compacted material which transfer the load onto underlying more competent horizons.  Generally a blanket or raft of selected material is compacted at surface to effectively transfer the loads onto the compacted columns.