Characterization of Dry-Stone Walls for the Stability Analysis of Terraced Slopes

Mediterranean terraced slopes, commonly characterized by dry-stone walls, are often affected by instabilities. This study aims to develop a methodology for parametrizing the mechanical behaviour of dry-stone walls for stability analyses and test it on a terraced vineyard in the Troodos Mountains (Cyprus). Dry-stone walls were characterized by treating them as fractured rock masses and applying an adapted version of the Geological Strength Index (GSI) classification. This approach focused on both the rock mass structure (i.e., the dry-stone wall, considering stones interlocking and wall homogeneity) and the conditions of discontinuities (i.e., stones surfaces, evaluating Joint Roughness Coefficient - JRC, weathering, infilling material and Joint Wall Compressive Strength - JCS). GSI values were translated into Mohr-Coulomb strength parameters; backfill soils was characterized via standard laboratory analyses. Stability was assessed using limit equilibrium numerical analyses. Field-based geomechanical characterization identified walls in good and poor condition. Stability analyses showed that good- condition walls favour stability for gentler slopes (≈ 20°) under saturated conditions, while poor-condition walls result in instability. Additionally, terraces with high riser (>= 2.0 m) and steep slopes (>=50°) showed instability even when completely dry. These failure surfaces did not involve walls, suggesting that such terrace geometries are inappropriate for the local conditions.