An insight into the stability of unsaturated embankments with different suction profiles

Abstract

As-compacted soil embankments are partially saturated and, during their lifetime, they experience changes in water content and suction according to interaction with the atmosphere and the groundwater table. However, conventional slope stability assessments often assume either dry or fully saturated conditions, which can lead to inaccurate predictions. This paper presents an analytical framework for the analysis of the stability of unsaturated embankments under different suction profiles. The limit equilibrium analysis is extended to unsaturated slopes by incorporating matric suction, degree of saturation, and rainfall infiltration. A novel design chart is introduced to illustrate the interplay between the hydromechanical parameters of the slope, its geometry, the position of the groundwater table, and the infiltration profile. The outcomes demonstrate the significance of suction and saturation distributions in the sustainable planning and safety evaluation of embankments, offering meaningful perspectives for enhancing design methodologies and prevent failures in unsaturated engineered slopes. A key finding is the identification of the transition infiltration depth, which delineates the shift from deep to shallow slip surfaces. If the wetting front remains above this threshold, the design chart remains applicable. However, if it extends beyond this depth, a more comprehensive stability analysis is required. The method has been successfully used to predict the safety factor of engineered slopes under different suction profiles. Serving also as a benchmark for more advanced stability analyses, the design chart provides engineers with a practical tool for integrating unsaturated soil behaviour into geotechnical design, enhancing risk assessment and failure prevention strategies.