Comparison of collapse loads obtained in 2D and 3D slope stability limit analysis

The basis for the typical geotechnical designs of slopes and excavations are limit analysis calculations that assume 2D plane strain. The assumption is typically rather conservative, thus such design may require unnecessary additional construction material, as well as increase the construction timeand environmental costs. In this paper, we present limit analyses ofan embankment near a slope, typical for a temporary dead-end road in a mine or on a construction site. We modelled this problem in2and3dimensions, using Optum G2 and Optum G3software, respectively.The results show that the 3D analysis provides collapse loads significantly higher than the 2D analysis. The shapes of the sliding surfaces also differ, as the 3D analysis allows us to determine the shape of the sliding surface in places where a 2D cross-section must be taken overly conservative. It, therefore, allows a better understanding of the mechanical behaviour of the studied structure. The collapse loads differ significantly between 2D and 3D analyses, potentially justifying the extra effort required for 3D calculations.