<p><p><strong>Reference(s):</strong></p><p><em>Ashford et al. (2004)<br>Fordham and Purcell (1991)<br>Ghandi et al. (1999)<br>Gohl et al. (2000)<br>Narin van Court and Mitchell (1994a, 1994b)<br>Narsilio et al. (2009)<br>Solymar (1984)</em></p><p><strong>Method Summary</strong></p><p>Settlement can be measured almost immediately after blasting. Deep settlement markers such as Sondex casing or Borros anchors can be used to determine the settlement profile of the entire treated layer, and may be necessary to confirm that the required densification has been achieved. Surface settlement data alone has only limited ability to determine the success of the densification due to the difficulty of correlating ground improvement and settlement distributions with depth. Because of this, QC/QA programs should include a way of measuring the density and strength properties with depth, and this is usually done using SPT or CPT measurements.</p><p><strong>Accuracy and Precision</strong></p><p>Surface settlement measurements only provide an estimate of the total settlement in an area, not the settlement of individual layers.</p><p><strong>Adequacy of Coverage</strong></p><p>Surface settlement markers are inexpensive and the number of them needed to cover the entire blasting site is not prohibitive. However, deep settlement markers are more difficult and expensive to place. The time and cost required for deep settlement measurements is significantly greater than for surface measurements.</p><p><strong>Implementation Requirements </strong></p><p>Settlement measuring devices can be fairly inexpensive depending on the amount of automation, and placement of surface settlement markers is fairly easy. Deep settlement markers are more difficult to place, but can be installed by most contractors.</p><p><strong>General Comments</strong></p><p>Settlement measurements can be used in all applications of blasting densification.</p></p>