| Description |
Secondary compression of foundation soils can cause long-term settlement damage to bridges, their foundations and approach embankments, overlying pavements and other nearby constructed works. Because this type of settlement is long-term and manifests itself many months to years following embankment construction, it sometime goes unnoticed until it damages overlying or nearby infrastructure. Surcharging or preloading of the earthen embankments and underlying compressible soils is the most commonly deployed strategy to reduce the magnitude of secondary compression. Surcharging or overconsolidating of the foundation soils can be used to reduce the post-construction secondary settlement. In the course of this research twenty-two consolidation tests and eighty-eight time rate tests were performed on Pleistocene and recent fine-grained, cohesive, lacustrine deposits comprised of Lake Bonneville and more recent clays, most likely of Utah Lake origin located along the Wasatch Front. Prior to analyzing the data, the test results were screened using the sample quality designation (SQD). Plots of the adjusted amount of surcharge (AAOS) were plotted versus the normalized rate of secondary settlement (C?-/C?) and compared with the research performed by Ng (1998). The data from this thesis plots higher than that reported by Ng (1998). This higher trend agrees better with the long-term settlement performance monitoring data obtained from the I-15 Reconstruction Project. Data from the time rate tests were used to determine the C?/CR ratio giving a mean value of C?/CR = 0.0456. This value was also compared with the research performed by Ng (1998) which has a value of C?/CR = 0.0433, this correlates well. A plot of moisture content vs. CR was developed and compared with research done by Bartlett and Lee (2004). The data from this thesis tendline is slightly lower than that reported by Bartlett and Lee (2004), but still correlates well. The correlation of moisture content vs. the C?/CR ratio was explored which shows promise, but more observations are needed to improve the statistical support for this relation. |
