Numerical and parametric analyses of four unreinforced embankments on soft soils

Resumo

The conventional method of estimating safety factors during various stages of construction remains prevalent for embankment stability analysis. This typically involves employing stability charts, equations, Limit Equilibrium Methods, and the Strength Reduction Method, with the Limit Equilibrium Method being the most conventional and widely adopted. Additionally, there is an increasing trend in leveraging results from instrumented embankments for performance and stability analyses, indirectly assessing parameters such as horizontal and vertical displacements, pore pressure, and soil displacement volumes. Despite the widespread acceptance of these traditional methods, many studies tend to evaluate results individually, overlooking the benefits of direct comparison for a more comprehensive analysis. This study employs a variety of methods and approaches to assess the stability of embankments under different geometries and soil conditions. The safety factors for various embankment configurations are estimated directly using two stability charts (O'Connor and Mitchell, 1977; Barnes, 1991), two stability equations (Huang, 2018; Sampa and Schorr, 2024), the Limit Equilibrium Method implemented in GeoSlope software, and the Strength Reduction Method in Abaqus and Plaxis. Conversely, the results of the soil deformability analysis are normalized for the purposes of indirect stability analysis, with the Abaqus software serving this purpose. Analyses were conducted on models featuring either a single material for both the embankment and the soil foundation or different materials for each. The elastoplastic model employing the Mohr-Coulomb failure criterion characterized the behavior of granular materials, while modified Cam-Clay models implemented in Abaqus described the behavior of soft soils. The analysis results focus on three key aspects: (i) comparison of safety factors, (ii) establishment of behavior patterns from stability and deformability analyses, and (iii) discussion of limitations, accuracies, and advantages of the assessed methods and approaches. Finally, a critical analysis addresses the impacts of varying criteria used in Abaqus and Plaxis software for determining safety factors based on the Strength Reduction Method concept.