Theoretical relation between unified hardening model and sub-loading surface model

Hashiguchi sub-loading surface constitutive model is one of the most influential constitutive models for over-consolidated soil. Therefore, this model is selected to analyze in terms of theoretical principle and construction method, and compare with the unified hardening(UH) model proposed by Yao et al. Through comparison, the Hashiguchi sub-loading surface model defines a single mathematical formula to fit the variation rule of the internal variables of the over-consolidated soil, and thus it can describe the stress-strain relationship of the over-consolidated soil. UH model holds the strength characteristics of over-consolidated soil, so it can describe the stress-strain relationship of over-consolidated soil more accurately and reasonably, which shows that the UH model is more advanced and complete in theory. At the same time, the comparison between the predictions of the two models and experimental data also verifies the correctness and superiority of UH model in numerical calculation.