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

97be determined. The challenges with using dynamic analysis methods are (1) the ability of adriving hammer to fully mobilize the pile resistance (i.e., causing pile displacement tomobilize the resistance along the pile-soil interface) for an accurate measurement of pileresponses; (2) the use of representative dynamic soil parameters that greatly influence thepile setup quantifications; and (3) the performance of time consuming and inconvenient pilerestrikes. In fact, AASHTO (2010) acknowledges that it is not feasible in practices toperform static load or dynamic restrike tests over a long period of time to quantify the pilesetup.2.8.5 Estimating pile setupPile setup can be estimated using empirical, analytical, or numerical methods. Elevenmethods and their limitations are chronologically summarized in Table 2.18 and areexplicitly depicted in the following paragraphs. Based on a large number of load test data onconcrete piles driven into Shanghai clay soils, Pei and Wang (1986) observed a considerablepile setup and proposed Eq. (2.58) to estimate the pile resistance at any time (t) after EOD.This setup equation is purely empirical and does not incorporate any soil and pile properties.Furthermore, this method requires the determination of a maximum pile resistance (R max )defined at 100% consolidation of the surrounding soil (i.e., complete dissipation of excesspore water pressure), which is usually difficult to estimate in practices., ( ) - ( ) (2.58)where,R t= pile resistance at any time (t) after EOD, kN or kip,R EOD = initial pile resistance estimated at EOD, kN or kip, andR max= maximum pile resistance after completing soil consolidation, kN or kip.