Geotechnical and Numerical Analysis of Slope Stability: Case Study of Bessa, Algeria

Abstract

Landslides represent one of the most persistent and destructive natural hazards worldwide, causing severe human and economic losses that often amount to millions of dollars. Effective mitigation requires a comprehensive understanding of the geological, hydrogeological, and geotechnical factors controlling slope instability. This study presents a geotechnical and numerical analysis of slope stability along Wilaya Road No. 162, located at the western entrance to Bessa (Algeria), where recurrent landslides threaten road infrastructure and public safety. The investigation involved detailed field observations and laboratory testing to characterize the site’s geological formations, groundwater conditions, and deformation mechanisms. Slope stability analyses were performed using the two-dimensional numerical code TALREN 4, applying classical limit-equilibrium methods (Fellenius, Bishop, and perturbation techniques) to determine the safety factor and identify critical slip surfaces. The obtained results revealed low stability under natural conditions, primarily governed by clayey marls, seepage forces, and toe erosion. To enhance stability, several reinforcement options were evaluated, leading to the selection of a geotextile-reinforced slope system as the most technically and economically viable solution. This approach significantly improved the factor of safety, demonstrating its effectiveness in preventing further mass movement and ensuring long-term road protection.