Assessment of Stress History of Jiangsu Clay Deposits from Seismic Piezocone Penetration Testing (SCPTU) Data

Abstract

The stress history as indicated by the profile of overconsolidation ratio (OCR) or preconsolidation pressure of a soil deposit is one of the dominant factors that influence the engineering behavior of soils. A commonly used method to obtain the parameter is a laboratory oedometer test, which is of low accuracy and time consuming because of inevitable sample disturbance. The purpose of this article is to assess the capability of existing interpretation methods and develop new methods to reasonably predict the OCR of clayey soils utilizing the seismic piezocone penetration test (SCPTU) data. Seven sites in Jiangsu province of China were used for this study. At each site, in situ SCPTU tests were performed and soundings of cone tip resistance (q c ), sleeve friction (fs), pore pressures (u 2), and shear wave velocity (Vs) were recorded. High-quality Shelby tube samples were collected close to the SCPTU 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 SCPTU methods overpredict the laboratory-calculated OCR. The collected data were further used to develop two new SCPTU methods that can estimate the OCR reasonably.