Shakedown ranges and dynamic shakedown strength for saturated clay under cyclic traffic loading

To gain deeper insight into the long-term cyclic deformation behaviour of saturated clay under traffic-induced loading, a series of undrained cyclic tests were conducted using a hollow cylinder apparatus on Shanghai saturated clay. A kinematic yielding framework was employed to interpret the permanent deformation response under varying cyclic stress levels. The permanent axial strain during the cyclic compression stage is used to identify distinct shakedown ranges of saturated clay, which can be validated by accumulated excess pore pressure, energy dissipation, and damping ratio. A comparison analysis was also conducted between static and dynamic strength parameters, including the plastic shakedown limit and the plastic creep limit. The experimental results indicate that the effective cyclic stress ratio serves as a more accurate indicator for identifying the shakedown ranges of saturated clay. Compared to dynamic shakedown strength parameters, the use of static strength parameters may lead to an overestimation of the shakedown limit by more than 100%. In addition, a simplified criterion is proposed to identify the distinct shakedown ranges of saturated clay based on the experimental observations.