Layer Identification and Strength Interpretation in Clay from Penetrometer Data

Penetrometer tests are used widely for offshore in situ site investigations and for soil characterisation in laboratory model tests. This paper presents a summary of two PhD dissertations and the work of a Research Fellow on penetrometers in layered clays. The continuous penetration responses of the commonly used cone penetrometer; and two increasingly used full-flow penetrometers (T-bar and ball) have been explored. Single layer, two-layer (soft-stiff and stiff-soft) and three-layer (soft-stiff-soft and stiff-soft-stiff) clay deposits have been considered. The investigations have been carried through large deformation finite element analyses and centrifuge model tests. Interesting and critical soil failure mechanisms are illustrated. Design frameworks are provided for the identification of layer boundaries, and interpretation of undrained shear strength of each identified layer.