Equivalent Interface Properties for FLAC and PLAXIS Models to Simulate Soil-Structure Interactions in MSE Walls

Yan Yu, Richard J. Bathurst, Ivan P. Damians, Antonio Lloret, Alejandro Josa

In the proceedings of: GeoRegina 2014: 67th Canadian Geotechnical Conference

Session: Soil Mechanics

ABSTRACT: 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) to model the reinforcement and program PLAXIS (finite element method) has only one ('geogrid' element). Both programs use different models and properties to simulate the mechanical behavior of the interface between dissimilar materials. The paper describes the details of the 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 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. RÉSUMÉ Le choix des éléments structuraux pour simuler les détails des renforcements de sol et l'interaction sol-structure pour la modélisation numérique des murs en sol renforcé, peut avoir une influence significative sur les résultats numériques. Le programme FLAC (méthode des différences finis) offre trois différentes options (poutre, câble et languette) pour modéliser le renforcement et le programme PLAXIS (méthode des éléments finis) n'en n'a qu'un seul (l'élément « géogrille »). Les deux programmes utilisent différents modèles et propriétés pour simuler le comportement mécanique de l'interface entre des matériaux dissimilaires. L'article décrit les détails du modèle d'interface de Mohr-Coulomb disponible dans les deux logiciels pour modéliser l'interaction entre les matériaux et décrit comment choisir les paramètres du modèle pour obtenir les mêmes résultats numériques. Les résultats numériques démontrent quantitativement les conditions qui mènent à un bon accord entre les deux programmes, pour le même problème d'interaction sol renforcé Œ structure, et les situations où il n'y a pas accord. Par exemple, l'article démontre que les résultats peuvent être très différents dépendant du type d'élément structural utilisé pour modéliser des couches de renforcement horizontales qui sont discontinues dans la direction des déformations planes. 1 INTRODUCTION Mechanically stabilized earth (MSE) walls have advantages with respect to ease of construction and cost over traditional concrete gravity and cantilever retaining walls, and are now used widely around the world. However, MSE walls are complicated mechanical structures with multiple design limit states for internal, external and facing stability modes of failure. Furthermore, the interaction between the backfill soil and the facing and reinforcement components strongly affect the performance of MSE walls. The numerical modelling of MSE walls requires the use of interface boundaries to simulate the discontinuity and transfer of normal and shear stresses from the soil to the reinforcement and facing components. Two numerical methods are generally used to model MSE walls: (a) finite element method (e.g., Cai and Bathurst 1995; Karpurapu and Bathurst 1995; Damians et al. 2013, 2014a) and (b) finite difference method (e.g., Hatami and Bathurst 2005, 2006; Huang et al. 2009, 2010; Damians et al. 2014b). However, the different treatment of the boundaries in these two programs and choice of reinforcement structure

RÉSUMÉ: alent Interface Properties for FLAC and

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Cite this article:
Yan Yu; Richard J. Bathurst; Ivan P. Damians; Antonio Lloret; Alejandro Josa (2014) Equivalent Interface Properties for FLAC and PLAXIS Models to Simulate Soil-Structure Interactions in MSE Walls in GEO2014. Ottawa, Ontario: Canadian Geotechnical Society.

@article{GeoRegina14Paper387,author = Yan Yu; Richard J. Bathurst; Ivan P. Damians; Antonio Lloret; Alejandro Josa,title = Equivalent Interface Properties for FLAC and PLAXIS Models to Simulate Soil-Structure Interactions in MSE Walls,year = 2014}