Assessing 3D stability of unsaturated embankments/slopes considering water level fluctuations using the minimum potential energy method

Water level fluctuations play a crucial role in the stability of unsaturated embankments as they can significantly affect matric suction. This study introduces a novel analytical method based on the minimum potential energy approach to account for these fluctuations in the embankment stability. The critical slip surface (CSS) is modeled as an ellipsoid governed by six parameters, with its determination achieved by minimizing potential energy of the sliding mass, optimized using the sparrow search algorithm (SSA). The method’s validity and accuracy are demonstrated through three case studies that explore the effects of various parameters, including water level, air-entry value ratio, pore size distribution ratio, and shear strength parameters, on stability and CSS location of embankments. The findings reveal that the safety factor (SF) obtained by the proposed method closely align with reference solutions, and highlight that the influence of air-entry value, pore size distribution, and shear strength parameters of foundation on embankment stability is modulated by water level changes. Notably, the failure extent of the embankment broadens with an increasing effective internal friction angle and diminishes with a decrease in pore size distribution ratio.