Assessing the Effectiveness of RIC/RDC Technique for Deep Fill Compaction Application-Paper

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The paper evaluates Rapid Impact/Dynamic Compaction (RIC/RDC) as an alternative to conventional roller compaction for thick granular fills. RIC/RDC uses an excavator-mounted hydraulic hammer to strike a ground-contacting compaction foot at 40–80 blows per minute, enabling compaction from the surface rather than placement and testing of many thin layers.<br /><br />A large-scale trial in Saudi Arabia tested two dune sands with fines contents of up to 8% and 15%. Compaction used three progressively closer grid phases, with a 16-ton hammer and different foot sizes. Cone penetration tests (CPTs) before and after treatment measured changes in soil resistance and assessed whether the target relative density of 70% was reached.<br /><br />Post-treatment CPT results showed substantial improvement, with cone resistance and sleeve friction increasing by approximately 100–500%. The 70% relative-density target was achieved to about 6 m in the lower-fines trial and about 5.5 m in the higher-fines trial. Stiffness increased at greater depths, although the target density was not consistently met below those levels. Estimated post-compaction elastic moduli reached 100 MPa and 75 MPa, respectively.<br /><br />The authors report that RIC/RDC can reduce project time by more than 50% and compaction costs by around 50% compared with conventional methods. Other benefits include high productivity, fewer equipment and supervision requirements, improved scheduling, and flexibility to use a wider range of fill materials. The technique is presented as a practical option for compacting substantial thicknesses of loose granular fill in a single bulk placement, provided that treatment performance is monitored and verified with CPTs.

Keywords

Rapid Impact Compaction

Dynamic Compaction

granular fill

cone penetration test

relative density

dune sand

soil improvement

compaction cost reduction

elastic modulus

bulk placement