# Geomechanical Basis for Assessing Open-Pit Slope Stability in High-Altitude Gold Mining
###### Abstract
To maintain real-time control over slope conditions, the GeoMoS automated monitoring system was implemented at the Bozymchak mine, enabling precise displacement tracking and the early detection of potential instability [9]. The integration of field testing, geophysical surveys, digital modeling, and automated monitoring used in this study allows for an objective and reliable assessment of slope stability at the Bozymchak deposit under complex geological and seismic conditions. This comprehensive approach supports the development of safe and efficient design solutions while minimizing operational risks and enhancing the overall stability of open-pit operations [10]. Some technological aspects of the mining system at the deposit include transport-based, layer-by-layer extraction with waste rock hauled to external dumps. According to the technical design, the working bench height is 10 m, reaching up to 30 m within the design contour. Two blasting schemes are used for ore and waste rock excavation. The final pit wall heights vary from 166 m to 266 m, with general slope angles ranging from 40\({}^{\circ}\) to 55\({}^{\circ}\). Selective ore blasting is carried out along a pre-cut trench on the hanging wall side of the ore body. In this approach, ore is blasted and hauled separately from waste rock, based on blast hole sampling. This scheme is mainly applied on the upper benches, where the width between pit walls allows for the placement of an inclined ramp and trench along the hanging wall without restricting the working face. Selective extraction may also be applied when pre-stripping waste blocks located in the hanging wall, using combined ore-waste blasting onto a buffer to preserve the rock mass structure. In this case, ore and waste are separated during excavation. The extraction block, located across the bench and ore body, includes hanging wall rock, ore, and footwall rock. Blasting is conducted onto a buffer of crushed rock and ore at least 6-7 m thick, left from the previous layer, preventing excessive fragmentation and the mixing of ore and waste. Excavation begins with the hanging wall rock, followed by ore and then footwall rock. The boundary between ore and waste is marked by the geology and surveying team using markers on the blasted rock mass. This scheme is mainly applied on the lower benches. Final ramp shaping and safety berm construction are performed using bulldozers. All temporary ramps are 24 m wide to support two-lane haul truck movement. The loading of waste rock into BELAZ-75558 trucks is carried out using Hitachi EX1200 diesel hydraulic excavators (bucket capacity of 6.5 m\({}^{3}\)). Blast hole drilling for both ore and overburden is conducted using ROC-6L and ROC-8 rotary-percussion rigs. Fragmentation drilling is planned for hole diameters of 127, 152, and 178 mm. The maximum ore lump size is 700 mm, and for waste rock, it is 1350 mm. Ore and waste loading is performed with EX1200 excavators into BELAZ-75558 haul trucks. The pit wall development to the final design position is carried out using pre-shear slotting, drilling inclined blast holes and detonating them with garland charges. The blasting of contour holes is performed under the following conditions:  
* Final bench slope angle--75\({}^{\circ}\), average built angle--71.5\({}^{\circ}\);
* Working bench slope angle--70\({}^{\circ}\), height--10 m;
* Safety berm of 10 m left every 30 m in depth;
* Contour hole diameter--127 mm. Pre-shear charges are detonated in advance, 25-30 m before mining approaches the design limit. Throughout the deepening of the pit, continuous geomechanical studies of near-slope rock masses and contacts are conducted, along with control over bringing slopes to their design contours.