Based on generalized potential theory

the modeling principle of establishing soil constitutive model and soil-structure interface constitutive model are similar; but the former is established in three-dimensional stress spaces according to triaxial shear test; the latter is established in two-dimensional stress space according to simple shear test. Under the simple shear test condition

the soil-structure interface problem can be regarded as a two-dimensional question in the space composed by normal stress and tangential stress

and the test result can be considered as two vectors

which composed by stress and strain respectively. According to the mechanical behavior of interface

the potential function and plastic state equation are determined; and general description of multi-potential surface interface constitutive model is deduced. Further

taking the two potential functions equal normal stress and tangential stress respectively

and a simplified multi-potential surface model of soil-structure interface is presented

which can be directly applied to the finite element numerical analysis. Finally

the proposed modeling method is verified by test examples. The model prediction results have been compared with experimental data; and results show that the modeling method is reasonable and practical. Research results indicate that the method presented is more convenient to establish the soil- structure interface constitutive model; and the elastoplastic stiffness matrix can be directly obtained without the determination of plastic potential functions and yield function.