SEDL / STP / STP1213-EB / STP13207S

Low Strain Dynamic Characteristics of Soils with the Downhole Seismic Piezocone Penetrometer

Campanella, RG
Professor, University of British Columbia, Vancouver, B.C.

Stewart, WP
Senior EngineerGraduate Student, Cook Pickering and Doyle Ltd.University of British Columbia, Vancouver, B.C.

Roy, D
Graduate Student, University of British Columbia,

Davies, MP
Senior Engineer, Klohn Leonoff Ltd.University of British Columbia,

Pages: 15    Published: Jan 1994

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Abstract

In-situ soil testing procedures with the downhole seismic piezocone have been under continuous development at the University of British Columbia since 1980. Currently, this rapid and cost effective tool can be used to measure the average dynamic soil properties of shear wave velocity as well as damping with depth along with the interpretation of detailed stratigraphy and geotechnical parameters. The purpose of this paper is to present, in a simple and practical way, the latest seismic piezocone procedures for testing and signal processing to determine low strain damping properties of soil in combination with the usual shear wave velocity measurements. The signal processing for shear wave velocity determination includes the phase velocity technique which gives shear wave velocity as a function of frequency. For the determination of the small strain damping ratio, the spectral ratio slope method is used. Typical results are presented and discussed for a site dominated by peat, organic soils and soft clays, all normally consolidated. Typical results for a sandy site are also presented.