<p><p><strong>References:<br></strong><em>ALLU (2007)<br>Dunnicliff (1998)<br>Garbin and Mann (2010)<br>Havukianen et al. (2011)<br>Jelisic and Leppanen (1999)</em></p><p><strong>Method Summary</strong></p><p>A primary objective of shallow soil mixing and mass stabilization is to improve settlement properties of a foundation soil. To ensure that the treatment is effective, settlement should be monitored for some time following treatment. Settlement is monitored primarily through traditional geotechnical means, i.e., surveying and settlement plates. For individual evaluations of these methods, see the GeoTechTools QC/QA documents for the Prefabricated Vertical Drains and Vacuum Consolidation technologies.</p><p><strong>Accuracy and Precision</strong></p><p>Methods of settlement monitoring are well-established. The results of these tests are accurate and precise.</p><p><strong>Adequacy of Coverage</strong></p><p>While surveying can be performed over an entire site with ease, other methods provide local results. Repeated measurements should be performed such that their data can be considered to cover the representative areas of interest.</p><p><strong>Implementation Requirements</strong></p><p>Methods of settlement monitoring are common in geotechnical engineering practice. Some special equipment and experience with the equipment is required. The FHWA Geotechnical Instrumentation Reference Manual (Dunnicliff, 1998) provides a detailed description of the equipment and requirements for planning a monitoring program.</p><p>General Comments</p><p>Settlement monitoring is important to determine the effectiveness of the SSM or MS. Excessive settlement indicates that either the design was inadequate or the design was not properly implemented. The behavior of shallow-mixed or mass-stabilized soil is different from traditional fine-grained soils in the short term (i.e., within approximately 28 days) following treatment. Shallow-mixed or mass-stabilized soils can compress a lot under the initial preload as curing occurs. Once the treated soil has cured, relatively little settlement should occur, and the majority of that settlement should occur as loads are applied. However, as indicated in the Mass Mixing Design Guidance, untreated soils underlying the stabilized soil may experience long-term settlements based on the consolidation characteristics of these underlying materials. In addition, long-term settlement may also occur in stabilized peat-type soils above the water table due to organic degradation. Such conditions should be evaluated during the design phase, and the period for monitoring should be appropriately established based on specific site conditions.</p></p>