A Comparative Study of the DPT and BPT in Evaluating Gravel Liquefaction during the 1983 Mw  6.9 Borah Peak, Idaho, Earthquake

Although the Becker penetration test (BPT) is known as the primary field test for evaluating the liquefaction potential of gravelly soils in North American practice, this test is not available all over the world. As an alternative, the liquefaction of gravelly soil has recently been correlated with the dynamic cone penetration test (DPT), which is relatively simple and cost-effective but more affected by large gravel particles. In this study, a comparison has been made between the performances of the DPT and the BPT when evaluating the liquefaction potential at 10 sites in Idaho in which liquefaction occurred in the 1983 Mw 6.9 Borah Peak earthquake. The cyclic resistance and cyclic stress ratios for the gravelly deposits were computed using both DPT- and BPT-based triggering procedures and compared. Both the DPT and the BPT identified the same critical layers and correctly predicted the liquefaction that occurred at these gravelly sites in Idaho. Both methods performed well in evaluating the liquefaction potential of loose- to medium-dense gravelly strata. However, the medium dense to dense layers were identified as nonliquefiable by the DPT, whereas the BPT identified those layers as marginally liquefiable.