A 1D-modelling approach for simulating the soil-pile interaction mechanism in the liquefiable ground

Abstract

The discrepancies between the dynamic response obtained with “Beam on the nonlinear Winkler Foundation” method, as a 1D model, and the actual pile behaviour in the liquefiable ground have been identified and marked in the vast body of literature. In this study, a 1D formulation is presented for the soil-pile system which provided considerable insights on the physics of the soil behaviour around the pile in the liquefiable ground and its dependence on soil properties. Unlike the mechanical models that may or may not be generalizable, the presented method is controlled by the soil properties. By a concept that the pile response is mainly influenced by the response of soil located on a unit volume in the pile vicinity, a macro-element is hypothesized by introducing a volumetric constraint incorporating the soil volume changes. The nonlinearity of macro-element is coupled in between volumetric and distortional behaviours where an incremental plastic work is assumed. Hence a stiffness matrix operator is used, instead of a scalar value, to link the pile resistance components with displacement components. A hypo-elastic bounding surface model was developed in this framework to capture the complex mechanism of soil-pile interaction in the liquefiable ground and presents a very good accord with available field measurement and centrifuge study while the computational time reduces to a couple of minutes for an earthquake excitation. An application for the presented 1D modelling approach is presented by calculating the instantaneous period and damping of the soil-pile interaction system in the liquefiable ground.