Abstract: A series of consolidated drained triaxial shear tests was carried out on compacted loess samples under different drying and wetting cycles to study the structural constitutive relationship considering the effect of drying and wetting cycles. The results indicated that the triaxial shear mechanical properties of compacted loess in different structural states were significantly different, which is indicative of obvious structural characteristics. Based on the analysis of the triaxial shear stress-strain relationship curves of compacted loess under different drying and wetting cycles, the triaxial shear structural parameters of drying and wetting cycles were defined according to the theory of comprehensive structural potential, and the rationality of the parameters was verified. The structural parameters were transformed and introduced into Duncan-Chang model to establish structural Duncan-Chang model which includes the effect of drying and wetting cycles. The comparison results showed that the calculated value of the constitutive model was basically consistent with the experimental value, which verified the rationality and applicability of the structural constitutive model. In accordance of the constitutive relation and parameters in this paper, taking a loess filling project as an example, the preliminary numerical analysis of which showed that the drying and wetting cycles had a great influence on the deformation of the filling foundation.

Key words: drying and wetting cycle, compacted loess, structural parameters, constitutive relation