<p><p><figure id='attachment_1482' style='max-width:500px' class='caption aligncenter'><img class="wp-image-1482 size-full" src="https://www.geoinstitute.org/sites/default/files/geotech-tools-uploads/…; alt="Photograph of vacuum tubes and the pipeline connections for a project in China." width="500" height="312" /><figcaption class='caption-text'> Site overview of vacuum tubes and pipe line connections. From Chang et al., 2010</figcaption></figure><h2>Basic Function:</h2>Hydraulic fill provides a rapid means of placing fill without hauling. Vacuum assisted consolidation with geo-composite drains provides the means to expedite consolidation of the hydraulic fill materials.<br><h2>Advantages:<em> </em></h2><ul> <li>Combining methodologies allows expedited construction</li> <li>Vacuum treatment reduces consolidation time</li> <li>Replaces standard preloading, eliminating risk of foundation failure</li> <li>Cost effective in comparison to conventional techniques</li></ul><h2>General Description:</h2>Combining these technologies, hydraulic fill, vacuum consolidation and horizontal drains allows the use of both waste and non-waste materials and expedites construction. Placement of horizontal drains in the fill eliminates the need for a geomembrane at the surface and allows for improvement of soil both above and below the drain. The preload of vacuum typically varies between 80 to 100 kPa for achieving the target of soil improvement. The hydraulic fill height is typically designed to be 3.5 m or greater for soil reclamation.<br><h2>Geologic Applicability:</h2><ul> <li>Method is applicable to very soft soils in coastal and inland areas, typically dredged and reclaimed grounds with high clay contents.</li></ul><h2>Construction Methods:</h2>Horizontal drains, consisting of prefabricated geocomposites, are placed during hydraulic filling. Vacuum loads of 80 to 100 kPa are applied to the drains are used to induce consolidation in the soils.<br><h2>Additional Information:</h2>The technology performs in the top of the ground surface for on-land applications, or below the water lever beneath the fine-grained deposit for underwater applications.<br><h2>SHRP2 Applications:</h2><ul> <li>Embankment and roadway construction over unstable soils</li> <li>Roadway and embankment widening</li> <li>Stabilization of pavement working platforms</li></ul><h2>Example Successful Applications:</h2><ul> <li>Field Test at the Pier 300 42-Acre Site, CA</li></ul><h2>Alternate Technologies:</h2>Soil replacement, raft foundation supported by piles, and conventional surcharge preloading.<br><h2>Potential Disadvantages:</h2><ul> <li>Equipment availability in U.S. is limited</li> <li>Performance data is limited</li> <li>Clogging of drains can occur, reducing effectiveness of technique</li> <li>Some applications are patented</li></ul><h2>Key References for this technology:</h2>Chu, J. and Yan, S. W (2005b). “Soil improvement using a combined vacuum and fill surcharge preloading method,” <em>Proceedings of the International Conference on Geotechnical Engineering for Disaster Mitigation and Rehabilitation</em>, December, Singapore, 452-459.</p><p>Dumas, C., Mansukhani, S., Porbaha, A., Short, R.D., Cannon, R.R., McLain, K.W., Putcha, S., Macnab, A., Lwin, M.M., Pelnik III, T.W., Brown, D.A. and Christopher, B.R. (2003). “Innovative Technology for Accelerated Construction of Bridge and Embankment Foundations.” Federal Highway Administration, U.S. Department of Transportation, Washington, D.C., FHWA-PL-03-014, 34.</p><p>Shinsha, H., Watari, Y. and Kurumada, Y. (1991). “Improvement of Very Soft Ground by Vacuum Consolidation Using Horizontal Drains.” <em>Conference on Geotechnical Engineering for Coastal Development</em>, Port and Harbor Research Institute, Vol. I, Yokohama, Japan, 387-392.</p></p>