Evaluating the Effectiveness of Shear Keys on Stability and Design Efficiency of Cantilever Retaining Walls

Retaining walls are critical geotechnical structures designed to resist lateral earth pressures, with sliding and overturning identified as primary failure modes. Although shear keys are commonly used to enhance sliding resistance, limited quantitative research has compared stability performance and design efficiency across varying wall heights. This study investigated the effect of shear keys on the stability and material use of cantilever retaining walls subjected to static lateral earth pressures by evaluating walls with and without shear keys at different heights. Stability analyses were conducted using Rankine's active earth pressure theory, followed by iterative optimization of the wall base dimensions to achieve a target safety of 1.5 for both sliding and overturning. The results demonstrate that shear keys significantly improve sliding stability and reduce the required base width, especially at lower wall heights. However, their effectiveness diminishes as the wall height increases, and sliding governs the design at higher heights. Additionally, the presence of a shear key yields only marginal reductions in concrete volume, indicating limited material savings. These findings provide practical insights for engineers in selecting and optimizing key shear designs, highlighting that their primary benefit lies in stability enhancement rather than material efficiency.