Comparison of BPT-SPT Correlations at Gravelly Alluvial Dam Site

摘要

A series of Becker Penetration Tests (BPTs) was recently conducted in a gravelly alluvial soil at a dam site in California to assess its liquefaction potential. The BPT program included both measurements of bounce chamber pressure, which is used in the Harder approach (Harder 1997), and a pile driving analyzer (PDA), which is used in the Sy approach (Sy 1993). The resulting equivalent Standard Penetration Test (SPT) blow counts from the Harder and Sy approaches were computed and found to differ significantly. As a result of the appreciable difference in equivalent SPT blow counts, each approach was critically reviewed, and a summary as it pertains to this site is presented. Results from additional site investigation using sonic boring and shear wave velocity measurements are also presented here, as they provide additional insight into interpreting the BPT results. This paper provides a useful case-history of a well-investigated site and compares the strengths and weaknesses of the current BPT approaches for calculating equivalent SPT blow counts.