The Critical Role of Site Characterization in Geotechnical Evaluation: A Case Study of Slope Stability Reinforcement with Soil Nailing

This study presents the reassessment and stabilization design of a failed stepped slope located above a power plant structure in Murgul, Türkiye. Site characterization combined unmanned aerial vehicle (UAV)-based Light Detection and Ranging (LiDAR) surveying and point-cloud processing with borehole investigations, Multichannel Analysis of Surface Waves (MASW), and Electrical Resistivity Tomography (ERT) to define the slope geometry and subsurface conditions. The integrated investigation identified a heterogeneous profile consisting primarily of slope debris, weathered tuff, and fractured rock, while also revealing the spatial limitations of the available borehole data. Based on the revised ground model, a permanent soil-nailing system incorporating slope regrading, reinforced shotcrete, and drainage measures was evaluated using limit-equilibrium and finite-element analyses in accordance with the Turkish Excavation Support Structures Code. For the DD-2 earthquake level, a pseudo-static horizontal acceleration coefficient of kh = 0.17 was adopted. The governing global factors of safety were 1.233 under static loading and 1.109 under pseudo-static loading, while the calculated maximum displacements ranged from 43 to 99 mm. The case demonstrates how spatially integrated site characterization can support the development of a traceable and code-compliant stabilization design for complex and previously failed slopes.