Numerical Modelling and Parametric Study of Unreinforced Masonry Block Arch Retaining Walls

A recently published experiment introduced a novel masonry concrete block masonry retaining wall system designed to resist lateral soil pressure by arch action. The system demonstrated several advantages: minimal deflection, ease of construction, cost-effectiveness, and aesthetic appearance. Despite the success of this system, the deflection profile of the wall was unexpected and could not be reproduced through numerical analysis, preventing complete characterization of the structural system. To define the parametric behaviour of this type of structure, a three-dimensional finite element simplified micro-model of the arch wall was developed using ABAQUS software version 2020 and verified against the experiment and existing analytical methods. The influences of the arch rise-to-span ratio, wall height, and grouting pattern were explored. The results revealed that arched retaining walls responded in a combination of arch action and cantilever behaviour, with the cantilever component diminishing with increasing wall height and curvature. For a given wall width, hollow arched walls sustained higher pressures than a conventional grouted flat wall. A hollow arched wall with a rise-to-span ratio of 0.25 resisted 37% more soil pressure than a grouted planar wall of the same height and span. Arch action was thus demonstrated as an effective mechanism for masonry retaining walls.