For ground improvement in general three different methods can be recognized. For cohesive soils such as sand, gravel and some silty sands, compaction methods are a good solution for ground improvement. In case soils are difficult to compact such as clay, peat and soft silt layers soil replacement could be the solution. Instead of compacting, these soft soils are reinforced by installing sand-, gravel- or grout columns in order to improve the soils‘ characteristics. Another solution is drainage of pore water in soft soils like clay, peat and soft silty layers. By installing vertical strip drains the pore water is transported to the ground level surface reducing the pore water pressure between the soil grains. Reduction of pore water pressure enables faster settlement of soil embankments. This paper however concentrates on the Rapid Impact Compaction (RIC) technique which can be categorized under soil compaction methods. Woltman has developed specialized RIC equipment to perform soil compaction in a highly efficient way and suitable for various project types and challenges. This paper will give an insight into the approach, methodology, engineering, operations, soil investigation and testing for RIC works.
The RIC method is very suitable for final treatment of the upper strata. The RIC method increases soil stiffness and creates uniform soil bearing capacities of soil embankments. The RIC method was developed in the early 90’s for shallow compactions like runways, floor slabs and roadway subgrades. The RIC method in these days has been improved and developed which makes it possible to compact soil layers approximately up to a maximum between 6 and 9 meters below ground level. RIC is often used for land reclamation works sometimes in combination with other techniques like vibroflotation. RIC is a compaction method using an excavator mounted hydraulic impact hammer to compact cohesive soils like sands, silty sands and gravel. The energy of the hydraulic impact hammer blows is transferred into the soil with a circular shaped exchangeable compaction foot. The impact energy is transferred into the granular soils providing soil grains with a better distribution which increases the soil density.
In general the RIC method is performed according the following steps