Numerical analysis of failure mechanism observed in backfills supported by masonry walls

Masonry retaining walls are designed to resist lateral forces. Their stability is essentially warranted by the correct determination of the failure surface geometry. Accordingly, this study intended to investigate the influence of wall and backfill properties that control failure surface geometry of cohesionless backfills. For this purpose, the discrete element method (DEM) is utilized, and a series of parametric studies were conducted. As the wall-joint parameters reflect the mortar quality of the blocks that constitute the masonry wall, three binder types from weak to strong were defined. Additionally, loose to dense backfill soil conditions and wall-backfill interface properties were also investigated. The results indicate that in the case of a thin rigid wall, the failure surface of dense backfill is identical with the classical earth pressure theory. However, for the masonry walls with a higher foundation width, the failure surfaces are much deeper and wider; particularly on the active side compared to the classical earth pressure theories. In addition to that the deformation mechanism and the associated failure surfaces are greatly influenced from the mortar quality which results with either a deep-seated or sliding type of failure.