Undrained dynamic behaviour of peaty organic soil under long-term cyclic loading, Part II: Constitutive model and simulation

Abstract

Based on the experimental evidences presented in Part I, an empirical equation for the peaty organic soil is derived for calculating the accumulated plastic strain, in which the influencing factors such as the amplitude and number of cyclic loading, the cyclic static deviator stress and the static strength are considered. By regarding the accumulated plastic deformation under long-term cyclic loading as static creep, a constitutive model is presented. The modified Cam Clay model is incorporated in the proposed model to determine the initial stress condition which is necessary for subsequent calculation of accumulated plastic strain. Then, the proposed model is implemented in a finite-element formulation by using an implicit stress integration algorithm. Finally, this model is evaluated and validated through the applications to specific boundary value problems including element tests presented in Part I, a flexible shallow foundation subjected to long-term cyclic load and a road with a low embankment subjected to traffic load. The proposed methodology can be used to calibrate the design of dynamic machine foundation, road and others that involve long-term repetitive loading.