<p><p><figure id='attachment_2569' style='max-width:953px' class='caption alignnone'><img class="wp-image-2569 size-full" src="https://www.geoinstitute.org/sites/default/files/geotech-tools-uploads/…; alt="Photograph showing equipment used to install deep-mixed method columns." width="953" height="663" /><figcaption class='caption-text'> After Elias et al. (2006).</figcaption></figure><h2>Basic Function:</h2>Deep mixing refers to the blending of cement, lime, slag, or other binders in powder or slurry form to stabilize soil in-situ. Methods increase strength and decrease compressibility.<br><h2>Advantages:<em> </em></h2><ul> <li>Can be used in noise and vibration sensitive areas.</li> <li>High production capacity.</li> <li>Applicability to on-land and marine projects.</li> <li>Applicable in a large range of soil types.</li> <li>Relatively easy installation procedure.</li> <li>Dewatering is not required.</li> <li>Can be economical on large projects.</li></ul><h2>General Description:</h2>Binders in powder or slurry form are mixed into soil using rotating tools, chainsaw like mixing equipment, mixing probes or other devices. When the binder is in powder form, the method is commonly referred to as the dry method. When the binder is in slurry form, the method is commonly referred to as the wet method. The choice of application method will depend upon the characteristics of a particular site and the desired performance characteristics of the treated soil.<br><h2>Geologic Applicability:</h2><ul> <li>Suitable in soils that can be stabilized with cement, lime, slag, or other binders.</li> <li>Not suitable in soils with large cobbles or boulders.</li></ul><h2>Construction Methods:</h2>Mixing can be done with single-axis rotating tools to create single columns, multiple-axis rotating tools to create a set of overlapping columns in a single stroke, chainsaw-like mixing equipment to create continuous panels, mixing probes for mass stabilization, or other devices. For dry- and wet-method rotary mixing tools, binders are injected through the hollow stem of the rotating tool. Dry method columns are usually 2 to 3 ft (0.6 to 0.9 m) in diameter and less than 60 ft (18.3 m) deep. Wet method columns can b up to 8 ft (2.4 m) in diameter and are usually less than 100 ft (30.5 m).<br><h2>Additional Information:</h2>Deep mixing methods can be less expensive than excavation and replacement since the in-situ soil is used. Cost is increased by high mobilization and demobilization costs from the large machines so this method is not suited for smaller projects. The wet method produces spoil where the dry method is environmentally friendly and does not produce spoil.<br><h2>SHRP2 Applications:</h2><ul> <li>Embankments Over Unstable Soils</li> <li>Roadway and Embankment Widening</li></ul><h2> Example Successful Applications:</h2><ul> <li>I-95/ Route 1 Interchange Test Embankment – Alexandria, VA</li> <li>I-15 – Utah</li> <li>Cypress Permanent Replacement Project – Oakland, CA</li> <li>Oil Storage Tanks – Lafourche Parish, Louisiana</li></ul><h2>Complementary Technologies:</h2><ul> <li>Lightweight fills for embankment construction</li> <li>Deep mixed columns for column supported embankments.</li></ul><h2>Alternate Technologies:</h2><ul> <li>Column technologies.</li> <li>For construction on soft soils, removal and replacement, vacuum or traditional preloading and prefabricated drains..</li></ul><h2>Potential Disadvantages:</h2><ul> <li>The wet method requires large and heavy mixing rigs with large headroom and may be too heavy for softer soils.</li> <li>A simple, comprehensive, and reliable design procedure is not available.</li> <li>Lack of widely recognized quality assurance program.</li> <li>High cost for mobilization and demobilization.</li></ul><h2>Key References for this technology:</h2><ul> <li>Bruce, M.E.C., Berg, R.R., Collin, J.G., Filz,G.M., Terashi, M., and Yang, D.S., (2013). “Federal Highway Administration Design Manual: Deep Mixing for Embankment and Foundation Support.” FHWA-HRT-13-046, FHWA, Washington, DC, 244p.</li> <li>Rutherford, C., Biscontin, G., and Briaud, J-L. (2004). Design Manual for Excavation Support Using Deep Mixing Technology, Texas A&amp;M University, College Station, TX. 276 p.</li></ul></p></p>