The SPT N vs. relative density (D_r) correlations for cohesionless soils were examined in detail using available laboratory and field data. For these correlations, corrections are applied to N, giving the recommended normalized value of (N_1)_(60). The D_r is linked to (N_1)_(60) as a function of soil characteristics that include the particle size, aging, and overconsolidation. The three correction factors by Kulhawy & Mayne (1990) for sandy soils were found to be appropriate for a wider range of soils, up to gravelly soils with D_(50) at least on the order of 5-10 mm. Use of the large penetration test (LPT) could extend these correlations to larger sizes.
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