Behavior of masonry walls under reverse fault rupture: Foundation and non-foundation comparisons

Reverse faulting is among the most critical geohazards affecting surface structures in seismically active regions. This study investigates the seismic response of unreinforced masonry walls subjected to reverse fault rupture with a 60-degree dip angle using a 1:10 scale physical model. The walls, constructed from natural travertine using scaled compressive bricks (10×20×5 mm) and a mortar composed of cement, fine sand, and sodium silicate, were placed over SP-type poorly graded sand compacted to 80% relative density. Transparent glass panels were used to confine lateral deformation and enabled accurate tracking of fault-induced wall and soil displacements through high-resolution digital imaging. The results indicate that the presence of a shallow rigid foundation reduced wall rotation and lateral displacement by 38% and 27%, respectively, while decreasing settlement by 65%, limiting it to only 12 mm. However, concentrated stress beneath the foundation led to localized detachment of the supporting soil, referred to as a loss of support, posing risks of differential settlement. In contrast, foundationless walls exhibited more uniform deformation and penetrated up to 26 mm into the sand, moving synchronously with the underlying soil. Experimental observations clearly demonstrate that the presence of a foundation can significantly enhance wall stability under reverse faulting. These findings highlight the importance of foundation design and soil structure interaction in improving the seismic resilience of masonry systems in fault crossing zones.