Osterberg Memorial Lecture: Application of Seismic Piezocone Soundings to Bi-Directional Load Test Response-PPT Presentation

PPT Presentation

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The 2023 Osterberg Lecture examines how seismic piezocone testing can improve the interpretation and design of bi-directional pile load tests. In an Osterberg-cell test, a hydraulic jack embedded in a drilled shaft pushes upward against shaft resistance and downward against end bearing. Choosing the jack’s elevation—especially for multi-stage tests—is important for measuring these components effectively, and load tests can cost $100,000–$300,000. The lecture argues that standard penetration test (SPT) values are too crude for this decision.<br /><br />Instead, it recommends seismic piezocone tests (SCPTu), which provide four complementary soil measurements: cone tip resistance (qt), sleeve friction (fs), porewater pressure (u2), and shear-wave velocity (Vs). These data help characterize soil and rock layers, select jack elevations, and estimate the parameters needed for elastic-continuum analyses of pile load–displacement response.<br /><br />The lecture presents applications and case studies involving drilled shafts in Atlanta, Georgia; Calgary, Alberta; Charleston, South Carolina; and Vancouver, British Columbia. Examples include multi-stage Osterberg-cell tests and comparisons between measured load-test responses and predictions based on SCPTu data. Collectively, the cases demonstrate how in-situ measurements and analytical solutions can support more informed test planning and interpretation.

Keywords

Osterberg Lecture

seismic piezocone testing

bi-directional pile load tests

Osterberg-cell test

drilled shafts

SPT values

SCPTu

shear-wave velocity

pile load-displacement response

in-situ measurements