At the Bozshakol Copper Mine, Slide3 Was Vital for Life-Of-Mine Slope Stability Assessments
The Bozshakol copper mine, operated by KAZ Minerals, is one of the largest mining projects in Kazakhstan. To achieve long-term stability, optimize ore recovery, and reduce uncertainty, the geotechnical team needed an effective solution for managing the complex geological conditions of the mine’s pit slopes.
In this case study, you’ll learn how Slide3, our advanced 3D slope stability analysis software, was used during a life-of-mine slope design review to refine pit designs, mitigate risks, and enhance safety. For the full story, read the original conference paper by Bekzad Rakhmetov, Almas Abzhanov, Bayuprima Adiyansyah, Danila Gorokhov, Artemiy Zamorin, and Kenessary Smagulov and Neil Bar.
Bozshakol’s Geological Terrain
Located within the Central Asian Orogenic Belt, the Bozshakol copper mine is characterized by a Cambrian-Ordovician intrusive complex and a series of faults intersecting the site. Sandstones and intermediate to mafic volcanic rocks, such as lavas and tuffs, are the area’s main geological features, which are overlain mostly by clastic sediments dating from the Upper Cambrian to Lower Ordovician periods. Surrounding the mine are gently undulating hills, closed catchments, and lakes, which all can impact surface runoff and make slope stability more challenging.
Onsite processing facilities can handle 30 million tonnes of ore annually with an average copper grade of 0.33%, and the mine is expected to have approximately 40 years of remaining life. When the conference paper was written, the open pit was about 200 meters deep, 4.5 kilometers long, and 1.8 kilometers wide, and future pit slope heights were expected to exceed 400 meters.
Establishing Geotechnical Foundations for Bozshakol
The geotechnical team worked to establish reliable slope stability parameters with initial data from a pre-feasibility study. This provided a foundation for understanding the geological conditions, but additional data was needed to refine slope design and effectively manage risks.
The team conducted additional investigations, including drilling 21 diamond core boreholes and 65 reverse circulation boreholes, plus conducting geomechanical testing, geotechnical face mapping, photogrammetry, and over 2,000 laboratory tests.
Further key challenges involved assessing the risks of slope instability in faulted and weak zones, such as clay and saprolite, and managing pore pressures that could impact stability. As the mine progressed, the need for advanced modelling became apparent to accurately predict slope behavior and identify potential failure mechanisms.
Slide3 was introduced as the solution to conduct comprehensive 3D limit equilibrium analyses, and it allowed the team to model complex structural features, evaluate pore pressure impacts, and optimize slope angles.
Slide3 Brought Clarity to Slope Stability Assessments
Slide3’s advanced 3D limit equilibrium analysis (LEM) capabilities enabled the team to model the geological complexities accurately and make informed decisions about slope design. The software was used to analyze various potential failure mechanisms:
Rock Mass and Structural Analysis: The team used Slide3 to apply the Hoek-Brown failure criterion for fresh rock and Mohr-Coulomb parameters for saprolite and clay. This provided an accurate representation of material strength across geological formations, allowing precise calculations of optimal slope angles to reduce failure risks.
Pore Pressure Management: Data from over 60 vibrating wire piezometers (VWPs) were integrated into Slide3, allowing for detailed pore pressure modeling. By using Hu coefficients to represent saturation in different geological units, Slide3 helped identify areas where excess pore pressure posed a risk to stability.
Failure Back-Analysis: Slide3 allowed for back-analysis of observed slope failures, such as a planar sliding mechanism on the lower north wall identified by the Bishop method (see Figure 3), which had a FoS of 0.709. These insights helped the team implement targeted interventions, focusing resources where the risk of instability was highest.
These analyses gave the geotechnical team the ability to optimize slope angles and reduce uncertainty by accurately simulating geological behavior.
With Slide3, Bozshakol Safely Steepened Its Pit Slopes
Slide3’s analyses directly impacted the design of the Bozshakol pit slopes. The 3D LEM models confirmed that many slopes exceeded a FoS of 1.3, so the team could safely steepen pit walls in competent rock formations. However, nine critical risk areas were also identified, which prompted targeted changes. For example, Slide3's analysis of structurally-driven failures on the lower north wall helped the team stabilize slopes where FoS values were as low as 0.70 to mitigate imminent risks.
Wide geotechnical berms were implemented in fresh rock units to avoid rockfall risks and facilitate the safe steepening of slopes as part of the optimization strategy. In the clay-rich units, Slide3 advised more conservative slope geometries to manage the inherent weakness of these materials effectively.
Managing pore pressures was another critical aspect of success. Horizontal drains were deployed in response to Slide3’s modelling, which reduced pore pressures in saprolite and clay units, helping to maintain stability against fluctuating groundwater levels.
Slide3 transformed the team's understanding of the pit’s geotechnical challenges into a concrete plan for safer and more efficient mining operations. Its detailed, data-driven insights allowed for targeted interventions and optimized slope stability without compromising safety.
Slide3 Was the Software Bozshakol Needed
The team’s geotechnical understanding of the Bozshakol Copper Mine improved significantly from the pre-feasibility study to the operational stage, thanks to continuous data collection, laboratory testing, and real-time slope performance monitoring.
Slide3 then provided 3D modelling and slope stability assessments as part of a comprehensive approach, which also included ongoing structural model updates, effective pore pressure management, and advanced monitoring systems. These efforts together helped the team make informed design decisions.
Frequently Asked Questions About Slide3
What makes Slide3 effective for slope stability assessments?
Slide3’s advanced 3D limit equilibrium analysis (LEM) capabilities can provide a comprehensive evaluation of both simple and complex slope failures. You can model heterogeneous geological materials and structural conditions while incorporating the Hoek-Brown and Mohr-Coulomb failure criteria. And you can precisely model real-world geotechnical conditions with features like anisotropic materials, user-defined slip surfaces, and pore pressure scenarios.
What types of failure mechanisms can Slide3 analyze?
Slide3 can analyze several types of failure mechanisms, including planar, wedge, and spherical failures, plus complex failure mechanisms including Ellipsoid and Spline failure shapes. With LEM, Slide3 accounts for discontinuities, bedding planes, fault zones, and weak layers, which are critical in assessing potential structurally-controlled failures. The software also allows the assessment of rotational slips and translational slides, so it’s versatile for a wide range of geotechnical scenarios.
How does Slide3 assess pore pressures during slope stability assessments?
By incorporating pore pressure data through various methods, including the use of piezometric data as a grid, water tables and the Ru method, Slide3 simulates changes in pore pressure to show hydrostatic and excess pore pressures on slope stability – particularly in saturated and partially saturated conditions. And by modelling different pore pressure conditions, such as rapid drawdown or prolonged rainfall, Slide3 can help you predict and mitigate potential instability caused by fluctuating groundwater conditions.
Also, if you carry out ground water seepage analysis in RS3, the data can be directly imported into Slide3 as a grid of pore pressure.
How can using Slide3 for slope stability assessments increase ore recovery in mining?
Like in this case, engineers can conduct detailed stability assessments with Slide3 that allow for steeper slope designs in competent rock masses while maintaining a sufficient factor of safety. Steeper slopes mean reduced stripping ratios, leading to less waste material removal and more efficient access to ore zones. Slide3’s precise modeling helps optimize slope geometries, enhancing ore recovery by minimizing overburden and maximizing exposed ore, while still managing risks associated with slope instability.
What role does Slide3 play in proactive slope risk management?
Slide3 allows you to create a detailed model of geotechnical scenarios before and during excavation, and by assessing potential failure mechanisms under different loading conditions, it can help you design slopes that minimize risks. It models the effects of changes such as increased pore pressures or material degradation over time, which can help you implement risk mitigation strategies like slope flattening, dewatering, or reinforcement in advance. This proactive approach makes it easier to maintain slope integrity throughout the project lifecycle. The sensitivity analysis option in Slide3 can also be used to investigate the influence of the change in the material parameters on the output factor of safety.
