BASE RESISTANCE OF OPEN-ENDED PILES EVALUATED BY VARIOUS DESIGN METHODS

Abstract

The design bearing capacity of an open-ended pile depends largely on the accuracy of the design
method. Although the knowledge of shaft resistance has been understood quite well, the base resistance has
not yet been completely understood due to the effects of soil plugging. The mechanisms of soil plugging is yet
to be fully understood particularly for large diameter and long length piles installed in large construction
projects. This paper compares the base resistance of two open-ended field piles constructed in the Tokyo Bay
project evaluated by various design methods including cone penetration test (CPT)- and standard penetration
test (SPT)-based methods. In total, five design methods including the conventional American Petroleum
Institute (API) approach were included. In Japan, SPT-based design methods are used in practice. The CPTbased design methods, which are not popular in Japan were also included to evaluate their effectiveness. The
CPT-design methods discussed in this paper classify open-ended piles into plugged or unplugged modes. The
results reveal that the Fugro (i.e., CPT-based) and the API design methods overestimate the base resistance. In
contrast, the ICP (i.e., CPT-based) and Port and Airport Research Institute (PARI) (i.e., SPT-based) design
methods underestimate the base resistance. Based on the results, we can recommend the University of Western
Australia (UWA) design method (i.e., CPT-based) as it produces the nearest results to the actual base resistance
measured from the field load tests.
Keywords: Base Resistance, Cone Penetration Test, Design Methods, Open-Ended Piles, Soil Plugging