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.

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. 

One advantage of RIC is that the drop height and number of blows can be varied based on the soil conditions. Through a test program, we will work with the Geotechnical Engineer of Record (GER) to determine the appropriate improvement criteria and RIC set-up for various areas of the site. For a site with a mixed soil profile and varying thicknesses of sand and clay, the ability to accurately control the amount of energy delivered to the ground is critical as it allows one to improve the loose overlying loose soil without liquefying the fine grained soils below – providing more uniform compaction.

RIC is a high-frequency, controlled energy, soil compaction technique used to densify surface layers of soils (to a depth of 5 to 7 meters in most cases) with minimum impact on the immediate worksite environment. Rapid Impact Compaction is widely used to densify loose granular soils (sand or gravel) as well as loam fill and industrial brownfield sites for surface compaction, foundations and floor slab support, liquefaction mitigation and waste stabilisation.

A compaction plate is placed on the ground to be treated. A hydraulic hammer, generally weighing less than 10 to 15 tonnes, is fitted to an excavator and used to transmit compaction energy to the soil via repeated impact. Without specific site precautions, a safe working distance to sensitive structures can usually be defined on the order of 8 to 10 m, as a distance of 5 to 6 m can usually be adopted for classical structures. At that distance, noise levels are lower than 90 dBA.

It is possible to compact the ground near an adjacent site with rapid impact compaction. Rapid impact compaction suits to ground improvement in small spaces. As an example, we can apply this technique within or next to existing warehouses. In such cases, we monitor very carefully vibrations in adjacent structures during rapid impact compaction.