Discussion to the article Undrained shear strength prediction of clays using liquidity index, by Q. Wang, S. Qiu, H. Zheng, R. Zhang

This communication presents a critical discussion of the article “Undrained shear strength prediction of clays using liquidity index”, authored by Q. Wang, S. Qiu, H. Zheng, R. Zhang, and recently published in Acta Geotechnica (https://doi.org/10.1007/s11440-023-02107-9). Various inaccurate claims and flaws regarding the Authors’ newly developed three-parameter strength–liquidity index (S_u–I_L) models/correlations are highlighted and discussed herein. In particular, comparing existing two-parameter and their newly developed three-parameter S_u–I_L models, contrary to the Authors’ claims, no improvement in prediction accuracy is achieved over the two-parameter model by introducing a third model parameter. Rather, it is shown herein that the existing two-parameter and the Authors’ three-parameter S_u–I_L models are mathematically identical. Furthermore, two of the Authors’ newly developed S_u–I_L correlations, i.e., relating the triaxial-compression and shearbox derived strengths to the liquidity index, are shown to be inaccurate, forecasting gross under- and over-predictions of the measured strengths, respectively. This highlights the need for a reassessment of the proposed correlations, and emphasizes the importance of accurate and reliable correlations in geotechnical engineering.