Instrumented Becker Penetration Test. II: iBPT-SPT Correlation for Characterization and Liquefaction Assessment of Gravelly Soils
Publication: Journal of Geotechnical and Geoenvironmental Engineering
Volume 143, Issue 9
Abstract
The Becker penetration test (BPT) is a widely used tool for the characterization of gravelly soils, especially for liquefaction assessment. An instrumented Becker penetration test (iBPT) was developed and integrated into the standard, closed-ended Becker drill string. The iBPT produces a continuous profile of energy-normalized blow count values , which are computed using the acceleration and force measurements recorded directly behind the driving shoe. The profile is repeatable and unaffected by hammer driving energy or accumulated shaft resistance. This paper presents the correlation between iBPT and standard penetration test (SPT) values, which is necessary for performing liquefaction assessment in gravelly soils. In developing this correlation, field variability was addressed by comparing median iBPT and SPT values from adjacent soundings over geologically consistent depth intervals. A framework was also developed to assess and, when appropriate, correct for gravel influence on measured SPT blow count values. This framework uses SPT blows per inch as well as physical evidence from SPT and adjacent Sonic samples. The correlation factor between iBPT and SPT is shown to be a constant value of 1.8 and independent of soil type or penetration resistance magnitude.
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Acknowledgments
The authors appreciated the funding and support provided by the Division of Safety of Dams (DSOD) of the California Department of Water Resources (David Gutierrez and Richard Armstrong) and Los Angeles Department of Water and Power (Craig Davis and Adam Perez). The support of Bill Sluis, Daret Kehlet, Jon Pearson, Kevin Kuei, and Chris Krage of the Department of Civil and Environmental Engineering at the University of California, Davis, is also greatly appreciated. In addition, the support and collaboration of AMEC Foster Wheeler (Marty Hudson and Alek Harounian), AECOM (Wolfgang Roth and S. Nesarajah), GeoPentech (Jon Barneich, Andrew Dinsick, and Doug Wahl), and Great West Drilling (Jim Benson) is appreciated.
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Information & Authors
Information
Published In
Journal of Geotechnical and Geoenvironmental Engineering
Volume 143 • Issue 9 • September 2017
Copyright
©2017 American Society of Civil Engineers.
History
Received: Sep 10, 2015
Accepted: Jan 26, 2017
Published online: Jun 15, 2017
Published in print: Sep 1, 2017
Discussion open until: Nov 15, 2017
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