Abstract: According to the characteristics of stress-strain curve of clay and the relating characteristics of its stress path, a sand stress path constitutive model established by authors is extended to clay; thus a clay stress path constitutive model is proposed. Through the transformed stress method, the SMP criterion is applied to the clay stress path constitutive model; then the model can describe the general stress states reasonably. The clay stress path constitutive model is identical with the modified Cam-clay model when they are in the condition of bidirectional loading (area A) and unloading (area D); there are different methods for computing plastic strain in the condition of single-direction loading (area B and F); specially, in the area C and E, the clay stress path constitutive model can compute plastic strain which will be zero if the modified Cam-clay model is used. Compared with the prediction of the modified Cam-clay model on the test data of Fujinomori clay, the superiority of the clay stress path constitutive model is demonstrated when describing the characteristics of stress-strain of clay in the condition of different stress paths.

Key words: sand, clay, stress path, constitutive model, modified Cam-clay model