S - Kam Ng PhD Dissertation Final.pdf - Digital Repository of CCEE ...

291increased immediately and rapidly within a day after EOD and continuouslyincreased at a slower rate after the second day over the maximum monitoredduration of 36 days. A comparison of the gradients of the best fits obtained forvarious restrike data revealed that the logarithmic increase in total pile resistancegenerally followed the rate of the pore water pressure dissipation.3. The experimental investigation confirmed that the amount of setup at a given timedepends on soil properties including the coefficient of consolidation, the SPT N-value as well as the thicknesses of the cohesive soil layers along the embeddedpile length. Piles embedded in a cohesive soil with a larger coefficient ofconsolidation exhibited higher percent increase in total pile resistances. However,piles embedded in a softer soil characterized by a smaller SPT N-value led to ahigher percent increase in setup. The collected experimental data showedsufficient information for quantifying the pile setup using properties ofsurrounding soil, which is not promoted in the past studies.4. A new pile setup method incorporating the commonly used SPT N-value andhorizontal coefficient of consolidation as well as employing an equivalent pileradius was developed. This proposed method utilizes the initial pile resistanceestimated at the EOD using either CAPWAP or WEAP, which eliminates theneed for performing any inconvenient and costly restrikes or pile load tests. Theproposed setup method was successfully validated using additional twelvehistorical records and five well-documented tests completed by other researchers.The proposed method adequately estimated the pile setup with the differencebetween measured and predicted pile resistances being 8 and 11% for 90 and 98%confidence intervals, respectively.6. Based on the analysis performed using six external data sources on largedisplacement piles, the proposed method provides a better pile setup predictionfor piles with diameters smaller than or equal to 600 mm.7. The analytical study performed based on the test pile ISU8 embedded in a mixedsoil profile concluded that the amount of pile setup was smaller than that expectedin a complete cohesive soil profile. The observed pile setup followed the