Slope Stability Analysis of Highway Embankments Using Strength Reduction Method in PLAXIS 3D

Slope stability analysis is vital in geotechnical and highway engineering due to its direct implications on infrastructure safety and serviceability. This study employs the Strength Reduction Method (SRM) in PLAXIS 3D, a finite element-based software, to assess the stability of highway embankments under various slope geometries, embankment heights, and groundwater table (GWT) positions. A total of 72 cases were analysed, involving six slope ratios (1.25H:1V to 3.5H:1V), six embankment heights (1 m to 10 m), and two groundwater conditions (−4 m and 0 m). Results show that the Factor of Safety (FOS) decreases with increasing slope steepness and embankment height, while gentler slopes consistently exhibit higher FOS values. Rising the GWT to ground level reduced FOS values by up to 35%, highlighting the destabilizing role of elevated pore-water pressures. Comparative analysis revealed that gentler slopes improved FOS by up to 50% compared to steep slopes at higher embankments. The findings underscore the importance of adopting flatter slopes and effective drainage strategies in highway embankment design to ensure long-term stability.