This paper describes an investigation undertaken to study the development of stable bulging in drystone retaining walls using a two-dimensional plane strain distinct element numerical model. Development of the numerical model, informed by field study investigations and material tests from a case study wall, is presented. A parametric study of the influence of backfill properties, wall block properties, wall joint properties, and wall geometry on stability is then briefly outlined. Three-dimensional aspects of bulging in drystone retaining walls are also discussed. Stable bulging failure is simulated in a plane strain distinct element model using tapered blocks and a voided porous wall structure. This behaviour is validated using a simple limit equilibrium analysis. The extent of bulging under simulated surcharge loading is shown to be dependent on model stiffness, which is influenced by wall and fill material properties, voidage in the wall, and masonry bonding.

Keywords: Distinct Element Numerical Model, Field Study Investigation, Wall Joint Properties

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