• Week soils are improved by the installation of compacted columns.
  • Carried out by compacting with the drop hammer.
  • It identifies surrounding granular soils.

 This technique involves the improvement of weak soils by the installation of densely compacted columns made from gravel or similar material. The displacement process reinforces all soils in the treatment zone and densifies surrounding granular soils.

Common uses

  • Reduce foundation settlement
  • Increase bearing capacity, allowing reduction in footing size
  • Increase stiffness
  • Increase shear strength
  • Reduce permeability
  • Mitigate potential for liquefaction
  • Permits shallow footing construction in treated fills
  • Very effective for sand compaction and land reclamation

Process - The Top feed process

  • Using the drop hammer’s weight, compaction will be done, the temporary casing tube penetrates to the designed depth.    
  • The stone is added at ground level around the casing tube.
  • The stone falls through the space to the casing tube tip, and fills the void.
  • The drop hammer is then lowered displacing the underlying stone. This  process is repeated until a dense stone column is constructed to the ground surface.


  •    Economical.
  •    A process that can be adjusted to a wide variety of soil conditions and foundation requirements.
  •    Can be carried out to depths of up to 15 meters.
  •    Quicker execution so that subsequent structural works can follow very quickly.
  •    Standard shallow foundations are enabled which can lead to savings.   
  •    Environmentally-friendly as recycled materials can be used.   
  •    Extremely quiet with low vibration.

Quality assurance

In-house quality production management software enables us to capture and analyses data in real time and valid the performance of the ground improvement being carried out.
A variety of production parameters are generally logged during execution including depth, current, pull down force, uplift/pull down sequence, time and date and element number. Field trials can also be used to verify column production parameters, along with static load tests, single or group, column material compressive strength tests, and column diameter verification.