<p><p><strong>Reference(s):</strong></p><p><em>Byrne et al. (1998)<br>Gomez (2009)<br>Lazarte et al. (2015)<br>Porterfield et al. (1994)<br>Rogbeck et al. (2003)<br>Samtani and Nowatzki (2006)<br>Terzaghi et al. (1996)</em></p><p><strong>Method Summary</strong></p><p>This method tests the strength of an individual soil nail by applying a specific load to a nail and measuring deflections and strain of the nail. The verification test typically loads a sacrificial nail until failure (ultimate test) or to at least 200% of the design load thus verifying the pullout resistance. Verification tests are also used to determine an ultimate grout-to-ground bond value to be used for final design. Lazarte et al. (2015) defines failure as “the inability to further increase the test load while there is continued pullout movement of the test nail.” The proof test loads a certain percent of the nails (typically 5 %) to a load that is usually 125% or 150% of the designed load according to Porterfield et al. (1994). Proof testing can be performed on production nails. Verification tests occur prior to installation of production nails whereas proof tests are conducted concurrently with production nail installation. A hydraulic jack is used to load the nail while the load is measured with a load cell or pressure gage, and deflections of the soil nail are measured with a dial-gage. An exact description is found in Lazarte et al. (2015).</p><p><strong>Accuracy and Precision</strong></p><p>The applied load, nail strain, and deflection are readily measured. This test is commonly performed and the information gained is highly relied upon.</p><p><strong>Adequacy of Coverage</strong></p><p>A small percentage of nails tested in each soil type encountered provide adequate coverage. Depending on the site conditions, more or less tests are required. Typically, 5% of installed nails are proof tested and one or two nails are subject to verification testing for each soil strata encountered. In Rogbeck et al. (2003), a chart is provided to determine the amount of tests necessary based on number of nails and area covered.</p><p><strong> </strong><strong>Implementation Requirements </strong></p><p>Pullout test are fairly expensive and time-consuming, but are a necessary component of quality assurance of soil nail walls. Samtani and Nowatzki (2006) recommend that an inspector training program be implemented.</p><p><strong>General Comments</strong></p><p>Verification tests assist in producing final design values and proof tests assure that the installed nails have adequate pullout capacity. However, the test can be expensive, time consuming, and limited in its coverage. Pullout verification testing is applicable to performance and method approach specifications.</p></p>