October 4, 2016
A tailings storage facility of a mine site in South America was analyzed using SVSLOPE®. With a maximum height of 50m, the facility was located in a mountainous region within a relatively narrow valley. The bottom of the valley consisted of soft clay deposits, while the side valley consisted primarily of coarse alluvial soil deposits. The embankment was founded directly on top of these soils deposits.
Three cross-sections, each one representing different foundation conditions along the embankment, were analyzed in SVSLOPE®2D to guarantee the physical stability of the facility. The cross-section that included the soft soils materials yielded the lowest 2D factor of safety through a deep rotational failure surface; the design of the facility was developed based on this finding. However, it was clear that the deep failure surface defined as a critical was a function of the soft clayey soil which did not take into account the 3D effects generated by the surrounding coarse alluvial materials.
To evaluate the 3D-effects induced by the foundation soils and the narrow valley on the physical stability of the tailings storage facility, a 3D slope stability analysis was conducted using SVSLOPE®3D. The three existing cross-section were rapidly interpolated to generate a 3D model: both the materials and groundwater level transitioned from 2D to 3D conditions. The 3D analysis resulted in a more shallow failure surface and higher factor of safety due to the influence of the coarse granular materials located on the side of the valleys. Further raises of the embankment will take into account these findings and will most likely include 3D analyses. SVSLOPE® proved to be a user-friendly and efficient tool to transition from 2D to 3D analysis using cross-sections as input.