Slope Stability and Reinforcement Analysis Using Front Cantol Cantilever Ground-Type Retaining Wall

Abstract

Soil, as a key material in geotechnical construction, has important mechanical parameters such as cohesion (c), internal friction angle (φ), and unit weight (γ), which are significantly affected by hydrological conditions. Rainwater infiltration can increase pore pressure and reduce soil shear strength, potentially triggering landslides, especially on steep slopes. The 2025 landslide in Aek Godang Arbaan Village, Onang Ganjang District, Humbang Hasundutan Regency, highlighted the vulnerability of the high slopes of provincial roads, which play a strategic role in regional connectivity. This study calculates the slope Safety Factor (SF) using the direct shear test shear strength parameters and the soil unit weight. The findings of the study provide a basis for designing an effective retaining wall to improve slope stability and support efforts to mitigate landslide risk to road infrastructure in the research area. Evaluation using the Fellenius and Bishop methods indicates that the slope was in critical condition. The geometric parameters of a slope, especially its height and slope angle, are the dominant factors that increase the likelihood of landslides. Laboratory test results indicate that the local soil exhibits index parameters and engineering properties that are sensitive to changes in moisture content. The relatively high plasticity and the influence of rainwater infiltration reduce cohesion and the internal friction angle, thereby reducing bearing capacity and slope stability. Furthermore, the analysis indicates that the alternative reinforcement using cantilever retaining walls is the most appropriate for the geotechnical and geological conditions of the research site. The implementation of this design significantly improves the slope's SF and maintains the function of provincial roads as strategic transportation infrastructure.