  This paper presents a new interpretation procedure to estimate the initial
state parameter from cone penetration testing (CPTu) in undrained conditions
based on the results from a comprehensive set of numerical simulations of CPTu
in low permeability liquefiable soil. CPTu simulations are performed using the
Particle Finite Element method, whereas the material response is modelled with
CASM. The effects of soil constitutive parameters and roughness of the
soil-steel interface are examined. It turns out that the numerical results are
correctly summarized by an analytical relation derived from undrained cavity
expansion results in critical state soils, as long as the constraints resulting
from cone geometry are taken into account. The resulting adapted analytical
formulation is notable for its simplicity and ease of use, comparing favorably
with existing alternatives.
