<p><p><figure id='attachment_3465' style='max-width:496px' class='caption aligncenter'><img class="wp-image-3465 size-full" src="https://www.geoinstitute.org/sites/default/files/geotech-tools-uploads/…; alt="Photographs of the high energy impact roller compactors used on the New Doha International Airport." width="496" height="395" /><figcaption class='caption-text'> Compactors on the project, with close-up. (Avsar et al. 2006)</figcaption></figure></p><p><h2>Project Summary/Scope:</h2><div></p><p>The airport consists of two parallel runways, 80 terminal gates, and capacity for handling 50 million passengers and 2 million tons of cargo per year. The project size was 22 km² with 65 million m³ of sand and rockfill reclaimed from sea at a production rate of 3 million m³ per month. After several compaction trials using different techniques (heavy dynamic compaction, conventional vibratory roller compaction, and high energy Impact Roller (IR) compaction with Broons BH-1300 and BH-1300 HD IRs), high energy impact roller was chosen as a better alternative. The compaction process using IR has been optimized using the Six Sigma quality improvement scheme.</p><p>Subsurface Conditions: Dredged sand and rockfill over seabed. The sand fill was calcareous, often shelly, and thus extremely crushable.</p><p>Compaction was carried out using nine IRs. Six of those had 8-ton modules and the other three had 12-ton modules. IRs are driven in fixed patterns and reverse their direction from clockwise to counter-clockwise after every ten passes. The following process parameters were used:<br><ul> <li>Roller operation speed – 10 to 12 km per hour.</li> <li>Impact rate – 1.8 to 2.2 impacts per second.</li> <li>Roller track width – 2.4 to 2.8 meters per track.</li> <li>Timing of water – 15 to 25 minutes/watering session.</li></ul></div><h2>Alternate Technologies:</h2>Heavy dynamic compaction, conventional vibratory roller compaction</p><p><figure id='attachment_3466' style='max-width:744px' class='caption aligncenter'><img class="wp-image-3466 size-full" src="https://www.geoinstitute.org/sites/default/files/geotech-tools-uploads/…; alt="A site map of the new Doha International Airport in which high energy impact rollers were used to compact site soils." width="744" height="635" /><figcaption class='caption-text'> Site of the new Doha International Airport. (Avsar et al. 2006)</figcaption></figure></p><p><figure id='attachment_3467' style='max-width:748px' class='caption aligncenter'><img class="wp-image-3467" src="https://www.geoinstitute.org/sites/default/files/geotech-tools-uploads/…; alt="An aerial photograph overview of the New Doha International Airport site which wherein site soils were compacted using a high energy impact roller." width="748" height="434" /><figcaption class='caption-text'> An aerial overview of the New Doha International Airport site. (Avsar et al. 2006)</figcaption></figure><h2>Performance Monitoring:</h2>Fill compaction requirements and testing included:<br><ul> <li>Cone penetration testing – at least 9 MPa cone resistance below mean sea level, never reducing with depth.</li> <li>In-situ dry density – 95% of the maximum dry density above the mean seal level.</li> <li>Settlement – maximum 25 mm at a design bearing pressure of 150 kPa.</li></ul>A direct result of the Six Sigma campaign on compaction was that the average in-situ dry density increased by 8% and the variance decreased by 56%.<br><h2>Project Technical Paper:</h2>Avsar, S., Bakker, M., Bartholomeeusen, G., and Vanmechelen, J. (2006). “Six sigma quality improvement of compaction at the new Doha international airport project.” <em>Terra et Aqua</em>, No. 103, June, pp14-22. <a href="http://www.terra-et-aqua.com">www.terra-et-aqua.com</a><h2>Date Case History Prepared:</h2>November 2012</p></p>