Axial Shaft Response Using Elastic Continuum and Seismic Piezocone Results

Abstract

The axial performance of drilled shaft foundations can be evaluated during the design stage using an elastic continuum framework and results from seismic piezocone tests (SCPTu). The SCPTu is an optimal means for collection of geotechnical data because the same sounding provides information on soil behavior at opposite ends of the stress-strain-strength curves, namely the peak strength for capacity and the small-strain stiffness (Emax) for the initial deformations. Using a Randolph-type elastic pile model, the approach can handle either the traditional top down loading applied using a reaction beam or the innovative Osterberg cell that simultaneously mobilizes the base and shaft in opposite directions. Case studies are presented for drilled shafts in soft clay, stiff clay, and hard clay till. ABSTRACT: The axial performance of drilled shaft foundations can be evaluated during the design stage using an elastic continuum framework and results from seismic piezocone tests (SCPTu). The SCPTu is an optimal means for collection of geotechnical data because the same sounding provides information on soil behavior at opposite ends of the stress-strain-strength curves, namely the peak strength for capacity and the small-strain stiffness (Emax) for the initial deformations. Using a Randolph-type elastic pile model, the approach can handle either the traditional top down loading applied using a reaction beam or the innovative Osterberg cell that simultaneously mobilizes the base and shaft in opposite directions. Case studies are presented for drilled shafts in soft clay, stiff clay, and hard clay till.