Examination of the correlation between SPT and undrained shear strength: Case study of clay till in Alberta, Canada

In this study, we introduce a novel method for estimating undrained shear strength (Cu) by incorporating SPT depth. A comprehensive dataset of 328 data groups from locations in Alberta was employed to investigate the correlation between Cu and various factors such as Atterberg limits, moisture content, sampling depth, and both field SPT numbers (N) and modified SPT numbers (N60), utilizing Pearson Correlation Analysis. The performance of the new approach was evaluated using metrics such as mean absolute error (MAE), mean square error (MSE), root mean square error (RMSE), mean absolute percentage error (MAPE), and coefficient of determination (R2). Comparative assessments of the new approach were made with existing approaches for Cu estimation. Furthermore, the proposed approach was applied to calculate Cu based on borehole information and moisture content data from 702 projects in Alberta, and its validity was verified against published information. The results demonstrate that the new approach yields Cu calculations with comparatively small discrepancies. This paper presents a reliable tool for estimating the average Cu of clay till in Alberta in a preliminary design state, with potential applicability to other regions as well.