Enhanced plasticity modelling of high-cyclic ratcheting and pore pressure accumulation in sands

Abstract

Predicting accurately the response of sands to cyclic loads is as relevant as still challenging when many loading cycles are involved, for instance, in relation to offshore or railway geo-engineering applications. Despite the remarkable achievements in the field of soil constitutive modelling, most existing models do not yet capture satisfactorily strain accumulation under high-cyclic drained loading, nor the the build-up of pore pressures under high-cyclic undrained conditions. Recently, bounding surface plasticity enhanced with the concept of memory surface has proven promising to improve sand ratcheting simulations under drained loading conditions (Corti et al. 2016). This paper presents a new model built by combining the memory surface conceptby Corti et al. (2016) with the well-known SANISAND04 bounding surface formulation proposed by Dafalias and Manzari (2004). The outcome is a new sand model that can reproduce phenomenologically the fabric evolution  mechanisms governing strain accumulation under long-lasting loading histories (here up to 104 loading cycles). In undrained test simulations, the model proves capable of correctly capturing the rate of pore pressure accumulation, preventing precocious occurrence of cyclic liquefaction.