Research on nonlinear constitutive model of interface considering cyclic softening

A zero-thickness interface constitutive model that considers cyclic softening and nonlinearity is proposed. Firstly, large-scale cyclic shear tests are conducted on the sand-steel interface to obtain the exponential softening law of strength parameters under cyclic shear tests. A cyclic softening equation considering a coupling effect of soil relative density and structural roughness is proposed. Secondly, a hyperbolic model incorporating the cyclic softening equation is used as the skeleton curve model to simulate the evolution of the interface from the initial state to the critical state under cyclic loading. Finally, considering the nonlinearity of interface shear, a hysteresis loop model of shear stress-shear displacement is constructed. In addition, empirical formulas for the strength parameters, stiffness parameters, normal stress, relative soil density, and structural roughness of the model are summarized. A newly established model is used to predict experimental results of this paper and existing literature, demonstrating its excellent capability in simulating interface cyclic shear tests.