<p><p><div></p><p><figure id='attachment_3401' style='max-width:626px' class='caption alignleft'><img class="wp-image-3401 size-full" src="https://www.geoinstitute.org/sites/default/files/geotech-tools-uploads/…; alt="Photograph of equipment used to install lime-cement columns during construction of I-15 in Utah." width="626" height="329" /><figcaption class='caption-text'> Lime-cement column construction, I-15 Utah (Elias et al. 2006a).</figcaption></figure></p><p></div><div></div><div></div><div></div><div></div><div></div><div></div><div></div><div></div><div></div><div></div><div></div><div></div><div></div><div></div><div></div><div></div><div></div><div><h2>Project Summary/Scope:</h2>The MSE wall, which is supported by deep mix columns, is located along westbound I-80 between the bridge crossing 200 West and 300 West. This project represents the first highway-related application of dry mix lime-cement columns in the U.S. The DRE system was used to stabilize soils to widen Interstate 15 East up to 15 meters (49 feet) and raise the roadway a maximum of 7 meters (23 feet) at the location of the bridge over 300 West Street. The air driven injection process of the dry method caused heaving. Cracks developed in the ground around the area of treatment to relieve underground pressures from the air injection.</p><p>Subsurface Conditions: The subsurface conditions consisted of up to 12 meters of clay with an OCR of 1.2 to 1.5 below a 3-meter crust. Water content ranged from 30 to 45% and PI’s were around 20. Below the upper clay is a 1- to 2-meter dense sand layer, which was typically underlain by interbedded sand and clay layers to great depth. Groundwater was encountered at about 3 meters below grade and artesian pressure from a depth of 18 meters was observed.</p><p>Columns about 22 meters long with diameters of 800 or 600 mm were used. The MSE wall was supported by panels of overlapping 800 mm columns approximately 22 meters long for the full width of the wall (approximately 0.7H) plus 2 meters in front and 2 meters behind the wall. The panels were spaced 2 meters center to center and had two cross-connections around the centroid of loading of the MSE wall. The retained fill behind the MSE wall was supported on 600-mm columns installed in a rectangular pattern between 1 and 1.2 meters apart and extending beyond the edge of the surcharge loading. The 800-mm columns were designed for a compressive strength of 600 kPa and the 600-mm columns were designed for a compressive strength of 800 kPa due to expected better mixing. A mixture of 85% cement and 15% lime was used with a dosage rate of 125 kg per cubic meter of treated soil.<br><h2>Alternate Technologies:</h2>Despite the planned installation of high-strength geotextile and staged construction of the embankment, primary consolidation was expected to be excessive and problematic to a nearby existing commercial building.<br><div class="mceTemp"></div><h2>Performance Monitoring:</h2>Unconfined compressive strength testing was used to verify the strength of the lime‑cement soil mixture. Vane shear tests and Swedish Probe tests were used at 7 and 28 days. Inclinometers were installed on the MSE wall. Load cells were installed on columns and on compressible clay. The design settlement was estimated to be 200 to 300 mm. Measured settlements after five months were about 100 mm and the revised projected total settlements were expected to be less than 150 mm. Load cells indicated that about 40 kPa was transmitted to the soil and about 400 kPa was transmitted to the columns.<br><h2>Project Technical Paper:</h2>Elias, V., Welsh, J., Warren, J., Lukas, R., Collin, J.G. and Berg, R.R., <em>Ground Improvement Methods</em>, U.S. DOT, Federal Highway Administration, Washington, D.C., FHWA NHI-06-019 (Vol. I) and FHWA NHI-06-020 (Vol. II), 2006.</p><p>Esrig, M.I, Mac Kenna, P.E., and Forte, E.P., (2003), Ground Stabilization in the United States by the Scandanavian Lime Cement Dry Mix Process, Geotechnical Special Publication 120: Grouting and Ground Treatment.</p><p>Farnsworth, C.B., Bartlett, S.F., Negussey, D., and Stuedlein, A.W. (2008). “Rapid construction and settlement behavior of embankment systems on soft foundation soils.” <em>Journal of Geotechnical and Geoenvironmental Engineering</em>. 134(3), ASCE, Reston, VA, pp. 289-301.<br><h2>Date Case History Prepared:</h2>November 2012</p><p></div></p></p>