Numerical modelling or conventional analyses? When an integrated approach becomes fundamental in understanding slope failure mechanisms

Abstract

Conventional kinematic and limit equilibrium analyses represent fundamental tools for slope stability assessment, especially under relatively simple geological and geometrical conditions. In structurally complex rock slopes, however, these approaches may be insufficient to fully describe failure kinematics, making integration with numerical modelling necessary. This study presents an integrated methodological framework combining conventional analyses and numerical modelling, applied to the Monte Conero coastal sector (Ancona, central Italy), an area characterized by a highly complex structural setting and significant exposure to rockfall and toppling hazards. Engineering geological and geomorphological surveys were combined with UAV-based photogrammetry and LiDAR to reconstruct slope geometry and discontinuity networks, providing the basis for kinematic and limit equilibrium analyses. While these methods allowed the identification of potential instability mechanisms, they were unable to fully reproduce deformation patterns observed in the field. Numerical modelling was therefore applied to simulate different geological and mechanical scenarios, enabling a more realistic representation of slope behaviour and failure mechanisms. The results highlight both the capabilities and the limitations of numerical approaches, underlining the importance of careful model calibration, validation and critical interpretation. Overall, the study demonstrates that an integrated analytical and numerical approach is essential for reliable slope stability assessment in structurally complex coastal environments and, at the same time, that geological interpretation remains the key component of any engineering geological assessment.