Analytical CPTU Models Applied to Sensitive Clay at Dover, New Hampshire

Abstract

Two analytical models for interpreting piezocone penetration tests (CPTUs) in soft sensitive Presumpscot clay were applied to in situ and laboratory results from a highway embankment project in Dover, New Hampshire. A closed-form limit plasticity solution provided the effective stress friction angle at both peak strength (ϕ1′) and maximum obliquity (ϕ2′) from the total cone resistance (qt) and pore-water pressure (u2) readings. A hybrid cavity expansion–critical state model provides undrained rigidity index (IR), undrained shear strength (su), and four profiles of yield stress ratio (YSR) with depth. The interpreted CPTU results compared favorably with independent benchmark values obtained from field vane shear tests and laboratory index, triaxial compression, and consolidation tests. As a supplement to soil behavior charts, an alternate means of identifying sensitive clays from regular insensitive clays is presented.