<p><p><figure id='attachment_1866' style='max-width:600px' class='caption alignnone'><img class="wp-image-1866" src="https://www.geoinstitute.org/sites/default/files/geotech-tools-uploads/…; alt="Schematic illustration of dynamic compaction. Diagram shows a crane dropping a weight into the ground with waves emanating from the resulting depression." width="600" height="561" /><figcaption class='caption-text'> Schematic illustration of dynamic compaction (Elias et al. 2006).</figcaption></figure></p><p><h2>Project Summary/Scope:</h2>A study site was used to test the effectiveness of deep dynamic compaction. CPT soundings were conducted pre- and post-treatment. The results were evaluated with respect to the effects of the amount of fines in the soil profile.</p><p>Subsurface Conditions: The study site is underlain by sand from 0 to 7.5 meters, with the water table at a depth of 4.6 meters.</p><p>A 9-ton weight was dropped from a height of 17 meters. Two passes were used.</p><p>The results of the study indicated that the amount of densification improvement in the soils above the water table was not influenced by fines content. CPT soundings demonstrated little improvement at depths below the groundwater table.<br><h2>Performance Monitoring:</h2>CPT testing pre- and post-treatment was conducted. The post-treatment soundings were taken near the center of the treatment grid. See the following figure.</p><p><figure id='attachment_1629' style='max-width:1200px' class='caption aligncenter'><img class="wp-image-1629 size-full" src="https://www.geoinstitute.org/sites/default/files/geotech-tools-uploads/…; alt="Graph of CPT fines content in percent with depth and CPT tip resistance with depth for pre-improvement and post-improvement." width="1200" height="750" /><figcaption class='caption-text'> Mackiewicz and Camp 2007</figcaption></figure><h2>Project Technical Paper:</h2>Mackiewicz, S.M. and Camp, W.M. (2007). “Ground Modification: How Much Improvement?” Geo-Denver Conference Proceedings, ASCE Geotechnical Special Publication No. 172: Soil Improvement.</p><p><a class="arrow-link" href="https://www.geoinstitute.org/sites/default/files/geotech-tools-uploads/…; target="_blank" rel="noopener">Download the paper</a><h2>Date Case History Prepared:</h2>November 2012</p></p>