<p><p><figure id='attachment_2628' style='max-width:625px' class='caption aligncenter'><img class="wp-image-2628 size-full" src="https://www.geoinstitute.org/sites/default/files/geotech-tools-uploads/…; alt="Schematic diagram showing placement of a shoot-in soil nail in a slope." width="625" height="335" /><figcaption class='caption-text'> Shoot-In Soil Installer Mounted on an Excavator (Figure from Barrett et al. (2002 ))</figcaption></figure><h2>Basic Function</h2>Shoot in Soil Nailing uses a high pressure system to insert passive inclusions into the ground as a temporary or permanent earth retention system.<br><h2>Advantages:</h2><ul> <li>More cost effective compared to alternate technologies</li> <li>Quick construction</li> <li>Can be constructed with limited headroom and limited right of way</li> <li>Can withstand large deformations</li> <li>Easily monitored and tested</li></ul><h2>General Description:</h2>Soil nailing is an in-situ soil reinforcement technique wherein passive inclusions (soil nails) are placed into the natural ground at relatively close spacing (3 to 5 ft.) to increase the strength of the soil mass. In shoot-in soil nailing, the soil nails are inserted by a launcher that is typically mounted on a hydraulic excavator using high-pressure air. The launcher typically launches plain or galvanized steel nails or fiberglass nails up to 1.5 inches in diameter and up to 20 feet in length. Shoot-in nails have seen much use in mountainous areas where rugged terrain limits construction options.<br><h2>Geologic Applicability:</h2><ul> <li>Work well in sands, gravels, silts, and clays.</li> <li>Soils with large boulders or cobbles are not suitable.</li> <li>Dense gravels and stiff clays will reduce penetration and are not preferable.</li> <li>Soils that are corrosive or prone to liquefaction or collapse when water is present are not suitable for the technology.</li> <li>A high groundwater table should be drained if the forces are too great. Water will decrease slope stability.</li></ul><h2>Construction Methods:</h2>Soil nails are inserted by a launcher that is typically mounted on a hydraulic excavator and uses high-pressure air acting upon a collet (plastic collar) which is attached to the tip of the nail. Compressed air suddenly released against the collet forces the collet and nail through the launch barrel. The nails are launched at speeds of over 200 miles per hour at pressures approaching 2500 psi. The collet breaks way as the nail enters the soil. As the launched nail passes into the soil, the ground around the nail is displaced by compression at the tip. The launcher typically launches plain or galvanized steel nails or fiberglass nails up to 1.5<br>inches in diameter and up to 20 feet in length.<br><h2>Additional Information:</h2>Nail capacities are in the range of 20 to 25 kips each. Soil nailing is recently starting to be used more often in mountainous terrain. Launched soils nailing is a relatively new technology. Obstacles restricting the spread of the use of the technologies include the lack of simple, comprehensive, and reliable analysis and design procedures, proprietary technologies, and the need for specialized equipment. The technology has similar or lower costs than its competing technology, drilled and grouted nails.<br><h2>SHRP2 Applications:</h2><ul> <li>Roadway and embankment widening</li></ul><h2>Example Successful Applications:</h2><ul> <li>Del Norte Bluff – Del Norte County, CO</li> <li>West Slope Reservoir Soil Nail Wall – Portland, OR</li> <li>Virginia Historical Society South Wing Addition, Richmond, VA</li></ul><h2>Complementary Technologies:</h2>Can be supplemental technology or used alone. Shoot in nails are typically used alone in places difficult to access or for small areas. Can be used with tiebacks or anchors and an SMSE Wall System.<br><h2>Alternate Technologies:</h2>Drilled/grouted and hollow bar soil nailing, Screw-in soil nailing<br><h2>Potential Disadvantages:</h2><ul> <li>Technology requires specialized contractor and equipment.</li> <li>Requires constant monitoring during construction.</li> <li>Inability to construct in sites where excessive drainage would be required, areas with soft clays, areas with freezing and thawing, expansive soils, soils with cobbles or boulders, and areas adjacent to structures or utilities sensitive to settlement.</li> <li>Lack of simple, comprehensive design procedure.</li></ul><h2>Key References for this Fact Sheet:</h2>Beekman, A. and Mallner, A. (2005). “Fiberglass Nail Pullout Capacity for Rapid Landslide Remediation.” EFRI at Rose-Hulman Institute of Technology, July 2005.</p><p>Myles, B., and Stevenson, P.E., (1994b) Project Report for Launched Soil Nails -1992 Demonstration Project, Vol 2, FHWA-FPL-93-003, Federal Highway Administration, July 1994.</p><p>Trimbath, K. (2006). “Soil Nail Launcher Strengthens Road Embankments.” Civil Engineering, Jan., Vol. 76 Issue 1, p34-35.</p></p>