Evaluation of Undrained Shear Strength Using Full-Flow Penetrometers

• Published in: Journal of geotechnical and geoenvironmental engineering Vol. 137; no. 1; pp. 14 - 26
• Main Authors: DeJong, Jason T, Yafrate, Nicholas J, DeGroot, Don J
• Format: Journal Article
• Language: English
• Published: Reston, VA American Society of Civil Engineers 01.01.2011
• Subjects: Applied sciences; Buildings. Public works; Estimates; Estimating; Exact sciences and technology; Geoenvironmental engineering; Geotechnics; Penetration; Penetrometers; Shear strength; Soft clay; Soil investigations. Testing; Strength; TECHNICAL PAPERS; Ball; Sensitivity analysis; CPT; In situ testing; In situ test; Measurement result; Shear strength; Penetration test; Flow; T-bar; Penetrometer; Sensitivity; Undrained strength; Flow(fluid); Soil test; Undrained soil test; Example; Full-flow penetrometer
• ISSN: 1090-0241; 1943-5606
• DOI: 10.1061/(ASCE)GT.1943-5606.0000393

Full-flow penetrometers (the T-bar and ball) are increasingly used on sites with thick deposits of soft clays, particularly prevalent offshore. Full-flow penetration tests were performed at five international well-characterized soft clay test sites to assess the use of full-flow penetrometers to estimate undrained shear strength. Field vane shear data were used as the reference undrained strength. Statistical analyses of strength factors indicates that full-flow penetrometers provide an estimate of undrained shear strength at a similar level of reliability compared to the piezocone. Relationships for estimating the strength factor and soil sensitivity using only full-flow penetrometer data obtained during initial penetration and extraction are developed. A strong dependence of the strength factor on sensitivity was identified and can be used for the estimation of undrained strength. The effectiveness and use of the developed correlations are demonstrated through their application at an additional test site.