A simple piezocone model combines spherical cavity expansion theory and modified Cam Clay concepts to represent both the corrected cone tip resistance (qT) and penetration pore water pressure measured behind the tip (ubt). In closed form, the undrained shear strength (su) is shown to be a function of the effective friction angle (φ\u27), the plastic volumetric strain ratio (Λ), and the piezocone parameter (qT− ubt)· Parametric studies show that the model is relatively insensitive to variations in φ\u27 and Λ, thereby simplifying its form for practical use. The method is applied to results from laboratory calibration chamber tests on kaolinitic clay, as well as field data from eight intact clay sites reported in the literature. In addition to in-situ PCPT records, these clay deposits have known profiles of su evaluated from laboratory isotropically and anisotropically-consolidated undrained triaxial compression tests
