Correction of mechanical CPT data for liquefaction resistance evaluation

For more than 30 years, there has been considerable interest in using CPT also to evaluate the liquefaction resistance of soils. Unfortunately, most of the simplified methods used for liquefaction resistance evaluation only require in situ measurements from electrical cone penetrometers even if they are frequently applied using measurements from mechanical CPTs that are still preferred by current engineering practice in many countries. Erroneous estimates of liquefaction resistance and relevant non-conservative results are obtained by applying electrical CPT-based methods to mechanical CPT data without any form of correction. This study focuses on the developing of an appropriate procedure for correcting mechanical CPT data and provides modified equations for liquefaction resistance estimation by means of electrical CPT-based simplified methods. A dataset of more than 3900 pairs of measurements of cone tip resistance and sleeve friction were obtained from 44 sites selected in Northern and Central Italy and processed by means of statistical analyses. Suitable adjustments to CPT mechanical data were proposed for determining corrected liquefaction potential.