Liquefaction resistance of partially saturated soils from CPTs

In this paper an experimental methodology to evaluate the undrained cyclic resistance of satu-rated and partially saturated sand from cone penetration tests is presented. The proposed methodology is based on the results of (1) undrained cyclic triaxial tests carried out on fully saturated and partially saturated sand samples and (2) centrifuge cone penetration tests. The tested soil is a natural sand retrieved from a site in Italy where liquefaction occurred in 2012. The results of centrifuge CPTs and undrained cyclic triaxial tests are interpreted in the frame of critical state soil mechanics and through a state parameter to calibrate a direct correlation between the cone resistance, qc and the undrained cyclic resistance ratio, CRR, accounting for the effect of the degree of saturation on the sand cyclic resistance. Velocity of P-waves is as-sumed as relevant variable to check the saturation degree.