<p><p><figure id='attachment_3586' style='max-width:600px' class='caption aligncenter'><img class="wp-image-3586 size-full" src="https://www.geoinstitute.org/sites/default/files/geotech-tools-uploads/…; alt="Photograph of a carefully sculpted and stained shotcrete finish." width="600" height="450" /><figcaption class='caption-text'> Carefully sculpted and stained shotcrete finish. (Photograph courtesy of Del Norte County, from www.soilnaillauncher.com)</figcaption></figure></p><p><div><h2>Project Summary/Scope:</h2>The bluffs on the coastline in Del Norte County were experiencing erosion. In the past, riprap had been installed to help mitigate the receding slopes. Because of permitting and environmental issues, the project engineer decided launched soil nails were the best option.</p><p>Subsurface Conditions: Six exploratory borings were completed. A CPT test was also performed. These showed that the soil nails would be launched into an unconsolidated fat clay and sand.</p><p>The nails were installed in a triangular pattern. Fiberglass nails with steel tips were used. Over 350 launched soil nails were installed. The nail launcher was attached to the boom of an excavator. It was able to sit on the ledge of the bluff and extend down and over the slope to install the nails. Drainage galleries were installed in areas of the wall where excess pore pressure behind the shotcrete wall was anticipated.</p><p>There were issues with launched nails going too deep into the soil. To rectify this, air pressure in the launcher was reduced. Another issue involved the steel tips getting shot off of the nails. An aesthetical issue was also presented with protruding drainage pipes. This was addressed by cutting the pipes flush with the slope and painting them a color that matched the surrounding wall.</p><p>The project took place over a five-week period from December 2008 to January 2009.</p><p><img class="aligncenter wp-image-3588 size-full" src="https://www.geoinstitute.org/sites/default/files/geotech-tools-uploads/…; alt="Photograph of the installation of corrosion resistant fiberglass Launched Soil Nails™." width="600" height="450" /></p><p><img class="aligncenter wp-image-3589 size-full" src="https://www.geoinstitute.org/sites/default/files/geotech-tools-uploads/…; alt="Photograph of a shotcrete installation where all work is being done from above." width="600" height="450" /><h2>Date Case History Prepared:</h2>November 2012</p><p></div></p></p>