Possible Evaluation of Overconsolidation Ratio of Clayey Soils from Piezocone Penetration Tests

Abstract

The purpose of this paper is to evaluate the capability of existing interpretation methods and develop new methods to reasonably predict the overconsolidation ratio (OCR) of clayey soils utilizing the piezocone penetration test (PCPT) data. These existing methods include the Schmertmann method, Kulhawy and Mayne method, and the Chen and Mayne methods using pore pressure measurements either at the cone tip (u1) or at the cone base (u2). Seven sites in Louisiana were used for this study. At each site, in-situ PCPT tests were performed and soundings of cone tip resistance, qc, sleeve friction, fs, and pore pressures at different locations (u1 and u2) were recorded. High quality Shelby tube samples were collected close to the PCPT tests and used to conduct laboratory oedometer consolidation tests to evaluate the reference OCR values. The predicted OCR values from different methods were compared with the laboratory OCR values. The results showed that all the investigated PCPT methods overpredict the laboratory calculated OCR. The collected data were further used to develop two new PCPT methods that can estimate the OCR reasonably.