Application of 3D slope stability analysis in defining the excavation conditions of coal at the open pits

Three-dimensional slope stability analysis has many advantages over the two-dimensional (2D), primarily due to more realistic view of slope geometry and slip surface, and involving side force resistance in the slope. Because of that in the paper, based on numerous 2D stability analyses applying the Morgenstern-Price method, critical slip surfaces were determined and 3D safety factors for them, involving the lateral resistance on the sides of linear lamellas excavation, were defined. Based on 3D stability analyses the zone excavation was proposed and width of slice excavation and safe distance from the front part of the slope were defined for each zone. The size of safety factor, obtained from comparative 2D and 3D stability analysis, clearly show that if 3D conditions were realized during excavation, as is the case with linear lamellas excavation, then much greater quantity of coal can be mined than when excavation is done in 2D stability conditions