# Geomechanical Basis for Assessing Open-Pit Slope Stability in High-Altitude Gold Mining
## 2 Materials and Methods
### Analysis of Fracture Orientations and Weakness Planes
However, in the event of a seismic event with a magnitude of nine on the Richter scale, the stability of certain sections of the northern wall may decrease to values between 1.147 and 1.241, which are still within the acceptable safety range. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & & & & **Stability Coefficient \(\mathbf{n_{y}}\)** & \\ \cline{3-5}
**Section Board** & **Name of Rocks** & **Side Height, m** & **Side Slope** & **Stability Coefficient \(\mathbf{n_{y}}\)** & **Stability Coefficient \(\mathbf{n_{y}}\)** \\ \hline
1 & 2 & 3 & 4 & 7 & 8 \\ \hline
1 & Granodiorites in the weathering crust, in & 166.4 & 35 & 2.934 & 2.450 \\ SE & the middle part and at depth & 234.0 & 45 & 1.483 & 1.286 \\ \hline
1 & Limestones in the weathering crust, in & 175.1 & 49 & 2.785 & 2.342 \\ SE & the middle part and in bedrock at depth & 224.0 & 45 & 1.496 & 1.297 \\ \hline
3 & Granodiorites in the weathering crust, in & 186.8 & 54 & 2.030 & 1.769 \\ SE & the middle part and in bedrock at depth & 221.0 & 40 & 1.662 & 1.430 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Assessment of the stability of the sides of the Bozymchak quarry according to the selected sections. Figure 6: Slope stability analysis: (**a**) northern wall; (**b**) southern wall considering the tectonic fault. The color zones represent different stability levels: green – stable area, yellow – conditionally stable, orange—potentially unstable, red—unstable zone. In addition, during the slope stability assessment of the southern pit wall, calculations were performed considering the presence of a major tectonic fault within the near-slope rock mass. This fault dips consistently with the surrounding rock mass, with a dip angle ranging from 40\({}^{\circ}\) to 47\({}^{\circ}\). However, the fault also intersects the pit wall diagonally and at varying depths from the wall surface--ranging from 66 m at the surface to 131 m at the pit base. The stability analysis showed that the safety factor was 1.597 when assuming cohesion along the fault plane of 10 t/m\({}^{2}\) and a friction angle of approximately 25\({}^{\circ}\), indicating that the fault has a relatively minor effect on slope stability. Even when the cohesion was reduced to 1.5 t/m\({}^{2}\) and the friction angle to 25.5\({}^{\circ}\), the safety factor remained at 1.552, confirming that the slope remained stable. According to current methodological guidelines, acceptable safety factors for pit walls should be at least 1.2, assuming a safety margin applied to the strength parameters of 1.2 and a slope service life of up to 10 years [18]. Under the geological conditions of the Bozymchak mine, a slope excavation method involving the creation of an advanced pre-shear groove along the full 30 m depth at a dip angle of 75\({}^{\circ}\), or at least in two sub-benches, is considered optimal. If this approach is approved by the design organization, the current slope design could be revised to adopt 30 m benches at a 75\({}^{\circ}\) inclination. This would make it possible to establish a single operational berm on the southern pit wall for cleaning off rock fragments falling from upper levels (Figure 6).