<p><p><figure id='attachment_2603' style='max-width:780px' class='caption aligncenter'><img class="wp-image-2603 size-full" src="https://www.geoinstitute.org/sites/default/files/geotech-tools-uploads/…; alt="Schematic of the principle of jet grouting operations." width="780" height="481" /><figcaption class='caption-text'> Principle of Jet Grouting Operation (After Kutzner, C. (1996). Grouting of Rock and Soil, A.A. Balkema, Rotterdam, 271p.)</figcaption></figure><h2>Basic Function</h2>Columns are created by injecting cement-based grout to create an in-situ soilcrete.<br><h2>Advantages:</h2><ul> <li>Nearly unlimited configuration of column geometry</li> <li>Can be installed in areas of limited headroom</li> <li>Can be used in a wide range of soil types and groundwater conditions</li> <li>Minimal settlement</li></ul><h2>General Description:</h2>Cement-based grouts are injected at high velocities from jets at the base of the drill string. These jets are oriented laterally (i.e., sideways). As the string is withdrawn from the soil and rotated slowly, the grout jet cuts and mixes the soil for a finite distance around the drill string forming column elements. The erosive/mixing action of the jet of grout can be enhanced in various proprietary systems by the supplemental simultaneous application of high pressure air and/or water.<br><h2>Geologic Applicability:</h2><ul> <li>Jet grouting can be used in all soil types but best results occur in cohesionless soils or soft cohesive soils.</li> <li>Can be completed above or below the groundwater table.</li> <li>Can be installed up to 150 feet (45 meters) deep.</li> <li>Highly plastic soils and fibrous peat soils that are less erodible are not recommended.</li></ul><h2>Construction Methods:</h2>Cement-based grouts are injected sideways into the soil from jets at the base of a drill string at high velocities. As the drill string is removed from the soil, it rotates and the jet of grout mixes with the soil to a certain distance. The mixing action of the jet can be supplemented by high pressure air and/or water if needed. Soil can be treated 3 to 15 feet (0.9 to 4.6 meters) in diameter. The diameter size depends on the soil and the grouting parameters selected. If the drill string is not fully rotated during the jetting, panels of the grout can be formed as hydraulic cutoffs. The depth of the grouting is generally less than 100 feet (30 meters) but has been used to depths greater than 164 feet (50meters). Care should be taken to avoid surficial or lateral movement. The spoils created during the jetting should be continuously discarded.<br><h2>Additional Information:</h2>The strength of the soilcrete is reflective of the quality of the soil. Sands and gravels will have a higher strength when grouted. Silts and clays will have a lower strength after grouting and poorer homogeneity. High levels of QC/ QA and safety awareness are needed for these soils. This technology has a high unit cost.<br><h2>SHRP2 Applications:</h2><ul> <li>Embankment and roadway construction over unstable soils</li> <li>Roadway and embankment widening</li></ul><h2>Example Successful Applications:</h2><ul> <li>Central Artery/Tunnel Project – Boston, MA</li> <li>Brigantine Cut and Cover Tunnel Project – Atlantic City, NJ</li> <li>Islais Creek Sewer Project – San Francisco, CA</li></ul><h2>Complementary Technologies:</h2>Generally a stand-alone technology. Could be used with column supported embankments with or without load transfer platform.<br><h2>Alternate Technologies:</h2>Tieback walls, cross-lot bracing for walls, drilled piers, micropiles, conventional underpining and dewatering.<br><h2>Potential Disadvantages:</h2><ul> <li>Installation may cause ground heave.</li> <li>Complex equipment.</li> <li>Generated spoils must be disposed of or used as fill.</li> <li>Can be more difficult in plastic soils.</li></ul><h2>Key References for this Fact Sheet:</h2>Brill, G.T., Burke, G.K, Ringen, A.R. (2003). “A ten-year perspective of jet grouting; Advancements in applications and technology.” Grouting and Ground Treatment, Geotechnical Special Publication 120, ASCE, 218-235.</p><p>Burke, G.K. (2004). “Jet grouting systems: Advantages and disadvantages.” GeoSupport 2004, Geotechnical Special Publication 120, ASCE, 875-886.</p><p>Schaefer, V.R., Berg, R.R., Collin, J.G., Christopher, B.R., DiMaggio, J.A., Filz, G.M., Bruce, D.A., and Ayala, D. (2016). “Ground Modification Methods,” Federal Highway Administration, Washington, DC, FHWA NHI-16-028 (Vol. II), 542p.</p></p>