Influence of choice of FLAC and PLAXIS interface models on reinforced soil-structure interactions

The choice of structure element to simulate soil reinforcement and soil-structure interaction details for numerical modelling of mechanically stabilized earth (MSE) walls can have a significant influence on numerical outcomes. Program FLAC (finite difference method) offers three different options (beam, cable and strip element) to model the reinforcement and program PLAXIS (finite element method) has two (beam and geogrid element). Both programs use different models and properties to simulate the mechanical behaviour of the interface between dissimilar materials. The paper describes the details of the linear elastic Mohr-Coulomb interface model available in the two software packages to model material interaction and how to select model parameters to give the same numerical outcomes. The numerical results quantitatively demonstrate the conditions that give good agreement between the two programs for the same steel strip reinforced soil-structure problem and the situations where they do not. For example, the paper demonstrates that results can be very different depending on the type of structure element used to model horizontal reinforcement layers that are discontinuous in the plane-strain direction.