Corrections to mechanical CPT results for use in liquefaction evaluation

Abstract

The cone penetration test is often used in geological and geotechnical surveys for characterising soil layers and to solve a wide set of geotechnical problems, especially for large scale studies that need to cover as wide an area as possible with more cost and time savings. For more than 30 years, there has been considerable interest in using CPT also to evaluate the liquefaction resistance of soils. The CPT-based simplified methods used for liquefaction resistance evaluation 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. In the present paper, a dataset of more than 3900 pairs of measurements of cone tip resistance and sleeve friction pertaining the same soil levels and measured with the two different types of cone penetration equipment (mechanical and electrical) were obtained from 44 sites located in Northern and Central Italy. Statistical analyses and regression processes allowed for the definition of some correction equations to be included in some of the most used CPT-based methods for liquefaction resistance estimation from CPT mechanical data. A probabilistic approach based on Taylor’s method was proposed for determining the uncertainties. Finally, the reliability of the suggested correction procedure was tested on the dataset available for this study.