 |
DFI Journal: Vol III Subscription: 2 Issues (No. 1 May 2009 and No. 2 Nov 2009) To order an electronic version choose Fedex/UPS Overnight Shipping and type in ELECTRONIC for Acct#., (DFI)
Evaluating Axial Elastic Pile Response from Cone Penetration Tests
Paul W. Mayne; Fawad S. Niazi
Axial pile performance can be rationally evaluated within an elastic continuum framework using
fi eld results from seismic piezocone tests (SCPTu). Adopting a versatile Randolph-type elastic
pile model, the approach can be applied to either traditional top down loading using an anchored
reaction beam or the newer Osterberg cell that simultaneously pushes the base and shaft in opposite
directions. The axial load distribution within the shaft is also evaluated. For site-specifi c data at
a given site, the SCPTu is an optimal means for collection of subsurface information because it
combines penetrometer readings and downhole geophysics in one sounding. The results obtained
are at opposite ends of the stress-strain-strength curves, specifi cally the peak strength for capacity
interpretations and the small-strain stiffness (Emax) for evaluating the initial deformations. Axial pile
capacity can be analysed using both direct and indirect CPT methods. As such, the approach allows
for a complete representation of the axial load-displacement-capacity curve for pile response. Case
studies are presented for deep foundations situated in stiff clays at two national geotechnical test
sites located in Houston and College Station, Texas, using top down loading, as well as a third case
study of a drilled shaft in clay till loaded by O-cell in Alberta.
|