Abstract: With the development of offshore engineering in recent years, foundation stability in ocean environment has become a hot topic for scholars and engineers. It is important to set up a simple saturated clay cyclic model for design of offshore structures under long-term cyclic loading. According to cyclic degradation behavior of saturated clay, a simple nonlinear model considering cyclic degradation of saturated clay is developed based on Hardin-Drnevich equivalent nonlinear model. This model can be adopted to describe the cyclic hysteretic characteristic of saturated clay, in which a degradation law for strength and stiffness with accumulated plastic strain as a variable is introduced. The physical interpretations of shape parameters and n, as well as residual ratio and damping factor are illustrated through parameter analysis. This model is proved to be able to describe the stress-strain hysteresis loops of different shapes and different degradation laws for strength and stiffness of saturated clay well by simulating the results of one-way cyclic triaxial tests and two-way cyclic triaxial tests in the literatures. With higher calculation efficiency, this simple model will be more suitable for engineering application comparing with the traditional elastoplastic models of soils.

Key words: saturated clay, simple nonlinear model, cyclic degradation