In this paper, calibration results of the hypoplastic clay model are presented by means of correlation analyses. The calibrations were performed using the online calibration application ExCalibre. The study defined two main objectives. First, to evaluate the reliability of the calibration application and, second, to determine comprehensive correlations between the model parameters and soil properties, such as Atterberg’s limits and soil gradation characteristics. While the calibration results are in agreement with critical state soil mechanics, thus proving the credibility of ExCalibre, a comprehensive analysis of the stiffness parameter, with the aid of response envelopes, revealed that this parameter should be treated as state dependent, which will be considered in future developments. Although the correlations found can be used for prompt parameter estimation, in this case, it was determined that the correlations cannot qualitatively replace a comprehensive calibration procedure.
Chinh et al. (2026) studied this question.