Numerical analysis of axial cyclic degradation of a single pile in saturated soft soil based on nonlinear kinematic hardening constitutive model

According to the cyclic degradation behavior of saturated clay, a nonlinear kinematic hardening constitutive model considering cyclic degradation for saturated clay is developed in commercial finite element software. A degradation law with the equivalent plastic strain as a variable is introduced in the isotropic hardening rule. The nonlinear kinematic hardening law is adopted to describe the cyclic hysteretic characteristics of clay. Degradation of soil stiffness is considered as well. The model is validated against the test results of saturated clay under one-way cyclic loading. Based on this model, 2D numerical simulations of a single pile under two-way axial cyclic loading by FEM are conducted. The degradation of axial bearing capacity of a single pile under different cyclic loading levels, cyclic loading numbers and stiffness indices of soil are studied. Finally, this numerical method is validated by simulating the results of model tests in the literatures.