Review of CPT based design methods for estimating axial capacity of driven piles in siliceous sand

Abstract

The Cone Penetration Test has been used for more than 30 years for soil exploration purposes. Its similarities in mode of installation with driven piles provides the potential of linking key variables of pile design and performance, such as base resistance and shaft friction, to measured cone tip resistance. Large scale pile load tests, performed in the last two decades, have shown better agreement with recent CPT based design criteria, than with conventional American Petroleum Institute (API) earth pressure approach design guidelines. The CPT based design methods provide a more coherent framework for incorporating soil dilation, pile size effect, pile plugging during installation, and the friction at the pile-soil interface. A review, of four recent CPT based design methods and the API design guidelines, for estimating axial capacity of driven piles in siliceous sands was performed by comparing their predictive performance to six documented on-shore piles with load tests. First, a detailed site investigation based on CPT data was performed to validate the provided soil profile, and to evaluate the accuracy of the CPT readings to identify and classify soil strata.

(cont.) Three piles were selected for further study and axial capacity calculations. Three of the design methods, UWA-05, ICP-05 and NGI-05, prove to accurately predict axial pile capacities for on-shore short piles founded on sites where sand dominates. Analysis against a larger and more detailed database is required to validate their performance in multilayer soil profiles.