Abstract: Natural clays have their structure which must be destroyed during the deformation process . In this paper a new kind of constitutive model capable to describe the damage of soil structure has been proposed. A structured clay in this model is regarded as an assembly of lumps of different sizes, and it is assumed that the total deformation consists of 3 parts, i.e. elastic deformation of lumps, plastic deformation due to sliding between lumps and irrecoverable deformation due to crushing of lumps. Usually yield function is introduced to describe the plastic deformation, however, a new damage function is proposed here to describe the additional deformation due to the damage of soil structure. Finally, a stress-strain relationship expressed in incremental form is formulated and a procedure is suggested to determine the model constants.

Key words: structured clay, constitutive modeling, yield function, damage function