The RIC is an innovative dynamic compaction device based on the piling hammer technology and is used to increase the load-bearing capacity of soils through controlled impacts. The general idea of this method is to drop a falling weight from a relatively low height onto a special foot assembly at a fast rate while the foot remains permanently in contact with the ground.

The compaction effect of the Rapid Impact Compactor is characterized by pulse-shaped loading of the ground and is achieved by a specific number of blows. The ground to be improved is both compacted and displaced depending on the soil type, thus, causing plastic deformations in the near-field while elastic waves are generated in the far-field. The nature of vibration excitation (transient or periodic) is one of the limiting factors for the allowable impact on buildings and human beings and has to be taken into account for the assessment of standardized limit values. 

The technique can usually be employed within 10-15m of sound structures with the vibrations significantly less than traditional dynamic compaction. RIC can also be used in shallow granular fills containing contaminants where penetrative ground improvement techniques such as Vibro Stone Columns would risk exposing contaminants to the atmosphere.  

The RIC attachment currently being manufactured by Hangshen is mountable on a regular hydraulic crawler excavator in the 30t to 65t operating weight category. During controlled impact the RIC’s 1.5m diameter foot stays in contact with the ground, ensuring efficient impact energy transfer to the ground at all times. Energy is imparted by dropping the weight through a relatively small height of up to 1.2m at a rate of between 30 to 80 blows per minute.

The latest generation HC models in the RIC range are available with drop weights of 5t, 7t, 10t and, more recently, a 16t version has been introduced. Treatment is effective in top layers typically down to 6m depth. The latest HC model, complete with a 10t drop weight, is fitted with a new sound attenuation pack which has been designed by Hangshen to significantly reduce the noise level produced by the compactor when in operation.

RIC increases the stiffness and shear strength of soils through the use of impact compaction effort. Specific benefits include:

Increases Standard Penetration Resistance – the standard penetration resistance (N-Values) of loose granular soil can increase significantly. In developing an RIC specification for a project the minimum target blow count for the performance required should be specified.

The energy and deflection of the soil is monitored and recorded at each location, which allows the geotechnical engineer to determine when effective treatment is complete. It also enables the engineer to identify weak zones (red dots) or debris zones throughout the pad so that any remedial actions that may be required can be minimized resulting in cost savings.