Based on the unified hardening (UH) model of reconstituted soil

a UH constitutive model is developed for structured clay. In this model

the dynamically moving normal consolidation line (MNCL) instead of the static normal consolidation line(NCL) is used as the reference line in determining the reference stress; and a proper increment evolution equation is proposed for the MNCL to describe the soil structural decay. The proposed structured soil UH model can reasonably simulate many behaviors of the structured soil

including the isotropic compression

strain hardening

strain softening

shear-induced shrinkage

shear-induced expansion

undrained shear decompression softening and coupling effect between soil structure and soil density. Compared to the original UH model

the structured soil UH model includes 3 new model parameters

which reflect the soil structure degree

the structure decay rate and the plastic flow rule

respectively. Comparisons between the test results and the model predictions of the three natural soils indicate that the structured soil UH model can reasonably describe the main features of the behavior of the structured soil.