Investigation of wedge sliding potential using different methods in two open pit albite mines excavated in gneiss in western Türkiye

The wedge failures in open pit mines are of great importance for bench configuration in jointed rock masses. This study initially determined 14 locations with wedge failure potential in two large albite mines, and extensive analyses covering conventional and deterministic approaches were performed. To fulfill the aims of this study, the values of safety factor for the wedges were obtained from three different analysis methods and compared with each other. It was found that the results obtained from the deterministic method that considers the weight of the wedge are in good agreement with those obtained from the stereographic projection method which considers the friction cone concept. On the contrary, the results obtained from the deterministic analysis are partly compatible with the ones obtained from the method that considers the wedge effect. Therefore, the method that includes the friction cone concept gives more realistic and accurate results than that of the method considering the wedge effect. Accordingly, the stable zones for the wedge slides among 14 locations of potential wedge failures were drawn on a stereographic projection net using the method that adopts the friction cone concept. Overall, it is feasible to rapidly evaluate bench stability and decision of bench geometry in open pit mining. Wedge angles (∈) and wedge effects ( k ) for the wedge blocks in the Cevizdere and Alipaşa open pits were determined as ∈≥ 83°, k ≤ 1.42 and ∈≤ 66°, k ≥ 1.72, respectively. The ideal k -values suggested by Hoek and Bray ( 1974 ) for the same wedge blocks were also determined as 1.33 ≤ k ≤ 1.50 and 1.50 ≤ k ≤ 1.80, respectively. The reason why the k -values of the wedge slides in the Alipaşa open pit is compatible with the ideal k -values; the ∈− angle creates a smaller acute angle (∈ ≤ 90°) than that of the Cevizdere open pit. It was determined that this situation caused the friction of the wedge block with the discontinuity surfaces forming the wedge to increase.