<p><p><strong>References:<br></strong><em>Bruce and Juran (1997)<br>DFI-ADSC (2002)<br>Gibler et al. (2005)<br>Gomez et al. (2008a, 2008b)<br>Sabatini et al. (2005)</em></p><p><strong>Method Summary</strong></p><p>Verification tests are conducted on pre-production micropiles installed following the same processes anticipated for production micropiles. Results from verification tests are used to confirm the adequacy of the design and construction process. At a minimum, one verification test is required for each significantly different soil or rock stratum where bond strength will be engaged. The micropiles are individually tested using a static load which is applied in compression, tension, or laterally and movement of the micropile head is measured for each load increment. The micropile is loaded and unloaded in increments until the specified maximum test load is reached. The micropile is loaded to 200 to 250% of the design load during verification tests. Because verification tests are carried to high loads, sacrificial micropiles are tested, which are not incorporated into the final structure. Three primary acceptance criteria must be met during verification testing of a micropile: rate of pile head movement at the test load, total pile head movement at the design load, and total pile head movement under sustained load (i.e. creep). If failure occurs during verification load testing, the design and/or the construction procedure must be adjusted to provide an acceptable capacity. Typical load testing equipment includes: a hydraulic jack and pump; reaction and reference beams; pressure gauges and load cells; dial gauges; and a wire with mirror and scale (Sabatini et al. 2005). Creep tests are performed as part of the verification test.</p><p><strong>Accuracy and Precision</strong></p><p>Verification testing accurately and precisely assesses the design and construction quality of a micropile project.</p><p><strong>Adequacy of Coverage</strong></p><p>Depending on the site and project conditions, more or less tests are required. On a typical project, at least one verification test is performed prior to production pile installation. Additional verification tests are required if significant subsurface variation exists in the soil stratum relied on for bond strength and/or projects where a large number of micropiles are installed.</p><p><strong>Implementation Requirements </strong></p><p>The requirements of verification testing are not excessive, although the amount of time required to conduct a verification test is greater than proof testing. As a result, verification testing is more expensive than proof testing. Verification testing is a required quality assurance procedure for all micropile projects.</p><p><strong> </strong><strong>General Comments</strong></p><p>Verification tests are performed to demonstrate the adequacy of design and construction method given similar subsurface conditions. “The results of a verification test can be used to provide an opportunity to verify the strength capacity of the micropile, establish load-deformation behavior, identify causes of pile movement, and verify the appropriateness of the assumed rock/soil shear strength used in design” (Gibler et al. 2005). These results are then used to determine the ability of the micropiles to carry an expected service load.</p></p>