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

161companion paper also show that pile setup mostly occurs along the pile shaft. Therefore,only the cohesive soil layers along the pile shaft are considered in the calculation of the N a .The average SPT N-value is calculated by weighting the measured N-value (N i ) at eachcohesive soil layer i along the pile shaft by its thickness (l i ) for total of n cohesive layerssituated along the embedded pile length, or it is simply expressed as∑∑ (4.5)As discussed before, the best fit lines demonstrate that the pile setup rate (C) for a specificsite is independent of the time (t) and R EOD . Therefore, Eq. (4.3) can be presented byreplacing (dR t /dt) with the horizontal coefficient of consolidation and the average SPT N-value as shown below.(4.6)The C h values were estimated from pore water pressure dissipation tests during CPT andcalculated using the strain path method reported by Houlsby and Teh (1988). In case C h wasnot measured, it can be estimated from its respective SPT N-value based on the correlationstudy discussed in the companion paper using Eq. (4.7)( ⁄ ) (4.7)The C h value in Eq. (4.6) was taken to be an average value calculated using an equationsimilar to Eq. (4.5). The soil parameters (C h and N a ) are listed in Figure 4.6. An equivalentpile radius (r p ) of 5.05 cm was calculated from the 80 cm 2 cross-sectional area of HP 250 ×63. Plotting the C values determined from Figure 4.3 for CAPWAP and from Figure 4.4 forWEAP-SA with thevalues in Figure 4.6, the relationship for Eq. (4.6) can be bestexpressed as