A Geomechanical Investigation for Optimizing the Ultimate Slope Design of Shadan Open Pit Mine, Iran

In this paper, a set of 3D numerical modeling was conducted using FLAC3D to assess the effect of the geomechanical parameters on the stability of the eastern ultimate slope of the Shadan Open Pit Mine. To this end, the effect of horizontal stress coefficient (k), slope curvature, and pore water pressure on slope stability of the mine was examined based on the strength reduction method and the minimum desired factor of safety (FOS = 1.20). The results showed that any increase or decrease in horizontal stress coefficient in the range of 0.05 to 2.00 while not changing the FOS causes slope deformation (especially horizontal and vertical displacements) in the pit wall slope. As a result, with decreasing horizontal stress coefficient (k), maximum shear strain values and horizontal and vertical displacements will decrease. On the other hand, with increasing K, the maximum shear strain and horizontal and vertical displacements in the floor and pit wall will increase. With decreasing slope curvature, the factor of safety will increase, leading to a decrease in deformations and displacements in the wall and floor of the pit. Furthermore, the groundwater drainage and reducing the pore water pressure behind the pit slope will decline the FOS, thereby reducing the deformation and displacement.