A Review of the Design Formulations for Static Axial Response of Deep Foundations From CPT Data

Niazi, F. S. & Mayne, P. W.

DFI Journal - The Journal of the Deep Foundations Institute

Volume 7, Issue 2, November 2013
DOI: 10.1179/dfi.2013.7.2.005

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A Review of the Design Formulations for Static Axial Response of Deep Foundations From CPT Data

Niazi, F. S. & Mayne, P. W.

Abstract

"Axial capacity analysis of deep foundations has been a topic of great interest in the soil-structure interaction problems. Soil behavior is governed by a series of complex stress-strain changes that occur during pile installation and subsequent loading. Owing to the difficulties and uncertainties on the basis of the soil strength-deformation characteristics, one of the most frequently followed design practice is to refer to the formulae correlating directly the pile axial capacity components of unit base resistance (qb) and unit shaft resistance (fp) to the data collected from cone penetration test (CPT). The elementary basis for such formulations has been the idea of considering cone penetrometer as a minipile foundation. This has resulted in plethora of correlative relationships in the past over 60 years. Such correlations, although empirical, have been worked out on the basis of load test results from both instrumented and un-instrumented full scale piles and are able to accommodate many important variables. A quick review of the evolution process and development of such design formulations is presented. An existing method is refined and modified to bring more convenience in extended applications. Few recommendations are proposed for future research directions, where the latest version of CPT i.e., seismic piezocone test (SCPTu) can be used to advance from capacity singularity to the complete axial pile load – displacement (Q – w) response."

Keywords:
static axial response, axial capacity analysis, CPT data