<p><p><figure id='attachment_2621' style='max-width:472px' class='caption aligncenter'><img class="wp-image-2621 size-full" src="https://www.geoinstitute.org/sites/default/files/geotech-tools-uploads/…; alt="Photograph of excavator-mounted rapid impact equipment and a resulting impact location." width="472" height="405" /><figcaption class='caption-text'> From Kristiansen and Davies (2004)</figcaption></figure><h2>Basic Function:</h2>Rapid Impact Compaction (RIC) provides controlled impact compaction to reduce settlement and improve geotechnical properties including stiffness and bearing capacity.<br><h2>Advantages:<em> </em></h2><ul> <li>More efficient use of energy to compact soil than deep dynamic compaction</li> <li>High quality of compaction in terms of degree and uniformity</li> <li>Versatility of movement of equipment</li> <li>Can be used close to existing structures</li> <li>Small foundation areas can be treated</li></ul><h2>General Description:</h2>RIC uses equipment mounted on an excavator that drops a weight to densify soils to a depth dependent on the groundwater, soil properties, and compaction energy. This technique is generally used on granular soils to improve the geotechnical properties and reduce settlement.<br><h2>Geologic Applicability:</h2><ul> <li>Technique is suited for a wide variety of granular soils and fills such as ash fills, waste fills and building wastes</li> <li>Not recommended for weak, low permeability soils with a high moisture content, for clayey soils and fills, or soils with high fines contents</li> <li>Effectiveness is dependent on soil properties such as degree of saturation, moisture content, and plasticity</li> <li>Groundwater may reduce densification if soil cannot drain. Groundwater level is recommended to be at least 3 feet (1 meter) below surface. Sump pump may be needed</li></ul><h2>Construction Methods:</h2>RIC is typically used to improve the geotechnical properties of granular fills and to reduce settlement. RIC has also been used in collapsible soils, ash fill, waste fill, and building waste. A 5 to 9 ton weight (4.5 to 8 tonne) is mounted on excavator equipment and is dropped about 4 feet (1.2 meters) on a 5-foot (1.5-meter) diameter tamper capable of imparting 40 to 60 blows per minute. The resulting force of this RIC process densifies soils to depths of 10 to 20+ feet (3 to 6 meters). Depth of compaction is dependent on compaction energy level, soil properties, and groundwater conditions. The higher the energy level, the greater the depth of compaction. Approximately 9,000 to 30,000 SF (800 to 2500 m²) can be covered in an average single-shift day.<br><h2>Additional Information:</h2>Quality control is performed by monitoring the compaction energy and deflection of the soil on each blow. Quality assurance is performed by recording the before and after results of the SPT N-value or CPT cone resistance until the required results are met for the zone needing improvement. Plate bearing tests have been used for different field trials to evaluate bearing characteristics. Peak noise levels have been recorded to be 88 dBA.<br><h2>SHRP2 Applications:</h2><ul> <li>New Embankment and Roadway Construction over Unstable Soils</li> <li>Roadway and Embankment Widening</li></ul><h2>Example Successful Applications:</h2><ul> <li>Pasco Middle School Building EE – Land O’Lakes, FL</li> <li>Tampa Terminal Tank 6 – Tampa, FL</li> <li>Naval Square Biddle Hall Annex and Townhomes – Philadelphia, PA</li></ul><h2>Complementary Technologies:</h2><ul> <li>Intelligent compaction</li></ul><h2>Alternate Technologies:</h2>Deep dynamic compaction, vibroflotation, stone columns, compaction grouting, excavation and replacement<br><h2>Potential Disadvantages:</h2><ul> <li>The depth of compaction cannot be controlled.</li></ul><h2>Key References for this technology:</h2>Serridge, C.J. and Synac, O. (2006). “Application of the Rapid Impact Compaction (RIC) technique for risk mitigation in problematic soils.” Proceedings of IAEG2006, London, Paper No. 294.</p><p>Simpson, L.A., S.T. Jang, C.E. Ronan and L.M. Splitter (2008) “Liquefaction Potential Mitigation using Rapid Impact Compaction.” Proceedings of the Conference of Geotechnical Earthquake Engineering and Soil Dynamics IV, Sacramento, CA, Paper No. 181.</p><p>Kristiansen, H. and Davies, M. (2004), “Ground Improvement Using Rapid Impact Compaction”, Proceedings from the 13^th World Conference on Earthquake Engineering, Vancouver, B.C., Canada, Paper No. 496.</p></p>