Physical Models of Dry Masonry Retaining Walls

Physical models are a sound tool for verifying some instability mechanisms. The authors apply these physical models to check the stability analysis of traditional dry granite masonry retaining walls as built in NW Spain. Unlike concrete retaining walls, dry masonry ones should be designed to ensure not only general stability but also an intrinsic one, since they can fail due to sliding through masonry contacts or to toppling mechanisms of parts of the wall. Accordingly, first, unfilled scaled retaining walls made up of small granite slabs are tilted until failure is observed, in this case due to toppling, following a stepped path. Secondly, simple retaining walls made of granite slabs are filled with sand of known friction angle until failure. In both cases, analytical expressions are applied to the model at stake, showing a rather good accuracy in predicting the observed phenomena. Some ideas are finally provided suggesting aspects that need a rigorous knowledge when applying the formulation to large size real cases. 1. INTRODUCTION In the words of Professor Einstein (2023), physical models are very suitable tools for verifying analytical models and the actual response of rock against specific failure mechanisms. Once verified, numerical approaches can help to expand the variation of parameters tested and carry out advance studies (back-analysis or sensitivity). Popular in the past, physical models are now hardly used by the rock mechanics community, probably due to cheaper numerical modeling options. However, they present some advantages in relation to modern numerical approaches. In this brief study, the authors present some rather simple physical lab-scale models of dry masonry retaining walls that were used first to identify the failure mechanism at stake and then to provide a verification of analytical formulations proposed elsewhere. The authors presented a study on the behavior and stability of traditional retaining drystone granite walls as traditionally built in Galicia, the northwest region of Spain (Alejano et al. 2012a and b). These structures are still commonly in use in this region for building and road construction, and occasionally, they achieve heights well over 10 m. They are generally cheaper and less environmentally aggressive than concrete walls and present an excellent landscape integration (Pozo et al., 2013), generating a low environmental impact, since the material used often comes from waste or low-price material from granite quarries producing large blocks for the ornamental stone market in the region.