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

159consider the immediate gain in pile resistance measured after the EOD, the time at the EOD(t EOD ) was assumed to be 1 minute (6.94E-3 day). Both CAse Pile Wave Analysis Program(CAPWAP) and Wave Equation Analysis Program (WEAP) with SPT N-value based method(SA as referred by Pile Dynamic, Inc. 2005) were selected for the following pile setupevaluations. Figure 4.3 presents the CAPWAP results by five linear best fits representing thefive test piles. A similar evaluation was also performed for the WEAP-SA method shown inFigure 4.4. Each best fit line was generated using a linear regression analysis based on therestrike results indicated by open markers. All linear relationships shown in Figure 4.3 andFigure 4.4 except ISU3 of WEAP analysis fit reasonably with the normalized pileresistances, confirmed by good coefficients of determination (R 2 ). For a comparativepurpose, static load test results, indicated by solid markers, are also included in the figures.The slope (C) of the best fit line describes the rate of a pile resistance gain; i.e., a larger slopeindicates a higher percentage of pile setup or provides a larger normalized pile resistance(R t /R EOD ) at a given time. Figure 4.3 and Figure 4.4 show that ISU2 (the short-dashed line)embedded in a relative soft cohesive soil (i.e., average SPT N-value of 5) has the largestslope of 0.167 for CAPWAP and 0.178 for WEAP. On the other hand, ISU5 (the longdashedand dotted line) embedded in a relative stiff cohesive soil (i.e., average SPT N-valueof 12) has the smallest slope of 0.088 for CAPWAP, and ISU4 (the long-dashed line)embedded in a relative stiff cohesive soil (i.e., average SPT N-value of 10) has the smallestslope of 0.141 for WEAP.4.4.2. Development of pile setup rateGiven that all test steel H-piles have the same size and the additional pile penetrationwas corrected for using the normalized embedded pile length (L EOD /L t ), the non-uniquenessof the slopes or pile setup rates (C) shown in Figure 4.3 and Figure 4.4 confirms that itsvariation depends on the surrounding soil properties. The general form of the proposed pilesetup equation is[ ( ) ] ( ) (4.1)