Determining Saturated Clay Parameters Using CPT and the Modified Cam Clay Model: Overconsolidation Ratio and Effective Friction Angle

This paper presents a finite difference-based analysis of the cone penetration test (CPT) in saturated intact clays. The modified Cam clay (MCC) model was used to capture the undrained behaviour of the saturated clays. The cone tip resistance values obtained from the numerical analyses were validated against those obtained from field and calibration chamber tests, as well as numerical analyses reported in the literature. The effect of the MCC parameters on tip resistance was investigated through sensitivity analyses. Based on a large number of numerical analyses of CPT with different MCC parameters performed in this study, a relatively comprehensive database of CPT results was obtained. Relative weight analysis was then used to determine the relative effect of each MCC parameter on the tip resistance. Using nonlinear regression analysis of the obtained database, a relationship between tip resistance and soil properties was developed. Finally, the application of the proposed equation in estimating the overconsolidation ratio and effective friction angle is illustrated with useful charts, numerical examples, and comparisons with different case studies.