Aktogay is a large open pit copper mine in Kazakhstan. Several geotechnical investigations have been completed from initial scoping and feasibility studies to continuous improvement studies during mining. Rock slope design has involved several phases of stability analyses for various stages and the life-of-mine open pit. With the progression of mining in the pit, ground conditions at the mine are becoming more apparent and uncertainty is progressively reduced. This paper briefly describes the slope stability modelling approaches used to understand and communicate geotechnical risks and opportunities for integration with a complex mine plan and sequence. A combination of 3D limit equilibrium and finite element analysis was incorporated into slope stability assessments for future slope excavation stages. The models have been developed with the intention of being digital twins to actual mine progression, with routine updating as engineering geological features are validated and updated with new exposures and additional site investigations.
Aktogay copper mine is located in south-eastern Kazakhstan, approximately 470 km to the north-east of Almaty, and 250 km west of the border with China. Mining operations commenced in 2015 and mine life is expected to be at least another 25 years.
The Aktogay deposit is located on the western part of the Central Asian Orogenic Belt (Li et al. 2018). It is confined to the eastern part of the Central Aktogai raft of volcanics and the enclosing pluton. The raft is intruded by Early Carboniferous, porphyritic granodiorite which also cross-cuts diorite and granodiorite of the Koldar pluton with the orebody striking west to north-west in an elliptical shape (Zvezdov et al. 1993). Major geological structures present in current and future pit slopes also follow this trend (Figure 1). Argillic-sericite alteration is focused on the core of the porphyry system and decreases outward (LeRiche et al. 2022).
A comprehensive geotechnical model has been developed from lithology, alteration, major structure and rock mass models as illustrated in Figure 1. These models were developed from a comprehensive data set from several site investigation campaigns including 162 geotechnically-logged diamond cored boreholes, 130 boreholes with machine learning core photograph classification and over 1700 geomechanical laboratory tests (LeRiche et al. 2022).
