<p><p><h2>QC/QA Guidelines</h2>Verification and proof load tests are effective in establishing the nail/ground interface strength. Verification and proof tests load the nail to a specified percentage of the design load. Verification tests load sacrificial nails to at least 200% of the design load. Results from verification tests are used to produce final design values. One or two verification load tests should be completed prior to production soil nail installation. During soil nail installation, at a minimum, two verification load tests should be performed in every different soil strata encountered. Larger projects will require more verification load tests (Lazarte et al. 2015 and Porterfield et al. 1994). Proof tests are similar to verification tests but load a production nail up to 150% of the design load. Proof tests are usually performed on 5% of the installed production nails (Lazarte et al. 2015). Results from proof tests are used to ensure consistent and acceptable installation methods and pullout capacities.</p><p>The creep test is normally conducted as part of a proof or verification test, in which the load test is maintained at a specified load while deformations in the soil nail over time are measured. The creep test can indicate how the loaded nail will behave throughout its service life under a constant load. Creep testing is typically only performed for projects where the soil nails are installed in cohesive soils where creep may be an issue. Creep tests should be performed at the same frequency as verification testing. Records of proof, verification, and creep test results should be kept to confirm design values have been achieved and adherence to specifications. This will help to ensure the wall’s longevity and ability to sustain the design load.</p><p>Visual inspection rapidly covers large areas and identifies problems such as cracking, seepage, and bulging, which may indicate failure. Inspection does not provide quantifiable results, but can identify major concerns, which should have been addressed. The wall should be visually inspected on a regular schedule in order to counteract a potential wall failure. Surveying is useful for monitoring the entire soil nail wall during and after construction for slope movements. Surveying is a more accurate and refined method to monitor wall movements. During construction, inspection of construction materials and activities verifies that samples from each batch of material conform to the design specifications and that proper construction procedures and design specifications are followed. Lazarte et al. (2015) provides a list of every item an inspector should verify and record in nail installation logs as part of project quality assurance.</p><p>Shotcrete cores are tested for compressive strength. Sampling, testing methods, and test frequency are described in Lazarte et al. (2015) and Byrne et al. (1998). These procedures help confirm that strength and property values defined in the specifications have been achieved.</p><p>In the laboratory, tension testing of representative nails verifies the batch’s ultimate tensile strength. Tension testing provides highly accurate and precise results for the strength of the nail which can be used as a QC tensile strength verification test. However, because nails come with certificates, the tension test is rarely used.</p><p>Inspections, construction observations, daily logs, and record keeping are essential QC/QA activities for all technologies. These activities help to ensure and/or verify that:<br><ul> <li>Good construction practices and the project specifications are followed.</li> <li>Problems can be anticipated before they occur, in some cases.</li> <li>Problems that do arise are caught early, and their cause can oftentimes be identified.</li> <li>All parties are in good communication.</li> <li>The project stays on schedule.</li></ul>Additional technology-specific details for inspections, construction observations, daily logs, and record keeping QC/QA activities are provided in the <em>Individual QC/QA Methods </em>section below.</p></p>