Abstract: The stress-strain characteristics of over-consolidated clay exhibit complex mechanical characteristics with the evolution of the degree of over-consolidation. Developing a practical constitutive model can provide powerful tools for the numerical analysis of over-consolidated clay. Initially, variation of the dilatancy behavior of over-consolidated clay with degree of over-consolidation is analyzed. By introducing the over-consolidation parameters into the dilatancy relation, a simplified dilatancy equation for over-consolidated clay is established. The dilatancy equation can be integrated as a plastic potential surface. Subsequently, a practical bounding surface model is developed within the framework of bounding surface theory, utilizing the proposed dilatancy equation through a straightforward theoretical approach. Finally, the performance of the model is comprehensively validated through triaxial drained compression and extension tests at multiple levels of over-consolidation, along with undrained triaxial compression and extension tests and complex stress path tests. The results indicate that the model effectively describes the stress-strain characteristics of over-consolidated clay with the degree of over-consolidation and exhibits significant advantages in simulating volumetric deformation and pore water pressure.

Key words: clay, over-consolidation, dilatancy relation, bounding surface model, critical state