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

267were plotted against the SPT N-value in Figure 7.23. Referring to the solid best fit lines ofthe data points, the poor correlation was substantiated with relative low R 2 of 0.40 for the J Tvalue and R 2 of 0.47 for the q T value. For a comparative purpose, the dynamic soilparameters determined from the default CAPWAP matching procedure for the same test pileswere similarly plotted against the same SPT N-value in Figure 7.23. The best fitting of thesedata points (represented by dashed lines of the open-filled circular markers) generated muchlower R 2 of 0.16 for the J T value and R 2 of 0.26 for the q T value. In other words, theproposed CAPWAP matching procedure gives a better estimation of these parameters.Despite the challenge with quantifying toe dynamic soil parameters in terms of anymeasureable soil properties, the results clearly indicate the toe dynamic soil parameters donot follow the typical constant value included in Table 7.1 as recommended by Smith (1962)and Hannigan et al. (1998).7.7. Validation of Proposed Dynamic Soil ParametersThe foregoing correlation studies not only provided successful quantification of thedynamic soil parameters in terms of SPT N-value, but also the match quality (MQ) of eachCAPWAP analysis has not been sacrificed during the proposed CAPWAP matchingprocedure. In fact, the match qualities, as shown in Table 7.7, have been improved by ashigh as 20%, based on matching the WaveUp (W u ) records (i.e., upward traveling force wavedefined by Eq. (7.6)). In addition, the match qualities for matching the force and velocityrecords have been improved in most cases as shown in Table 7.7. The improvement inmatching the measured and computed pile responses validates the proposed approach inquantifying the dynamic soil parameters.To expand the validation, an independent test pile, ISU8, not used in theaforementioned correlation studies, was selected for the CAPWAP analysis, based on theshaft dynamic soil parameters estimated using the proposed equations described in Sections7.5.1 and 7.5.3 for cohesive and cohesionless soil layers, respectively. Since the actual pileresistance was not measured using a static load test at EOD, the pile resistance of 621 kNestimated using the default CAPWAP matching procedure was maintained, while the