ASSESSMENT OF TECHNOGENIC IMPACTS ON SLOPE DEFORMATION IN LARGE-SCALE COPPER MINING: A CASE STUDY OF THE KALMAKIR OPEN-PIT MINE

Аннотация

Anthropogenic (technogenic) factors such as blasting, excavation sequencing, equipment-induced vibrations, and poorly designed drainage systems significantly influence pit slope deformation in large-scale open-pit mining operations. This study presents a detailed investigation of these influences at the Kalmakir copper mine in Uzbekistan. Using field data, geotechnical instrumentation, and Finite Element Modeling (FEM) via PLAXIS 2D, the stress redistribution and displacement patterns under various mining activities were analyzed. The results indicate that uncontrolled blasting and excavation without proper phasing contribute most to instability. Recommendations include optimized blast timing, vibration monitoring, phased excavation, and reinforcement strategies. Keywords: technogenic factors, blasting, slope deformation, pit wall stability, FEM, Kalmakir mine, mining-induced stress. In modern open-pit mining, geotechnical hazards are not only governed by natural conditions but increasingly by technogenic (human-induced) factors. In particular, activities such as drilling and blasting, improper excavation scheduling, and heavy machinery movement introduce significant dynamic and static loads to the pit walls. At Kalmakir mine — one of the largest open-pit copper operations in Central Asia — several minor slope failures in recent years have prompted investigations into operational practices contributing to instability. This paper assesses the impact of these technogenic factors and models their influence on slope stress and displacement. Table-1 The following anthropogenic influences were considered in this study. Factor Description Uncontrolled timing, excessive charge per delay, and poor burden Blasting control Excavation Uneven removal of material leading to unbalanced stress sequencing distribution Equipment- Vibrations from haul trucks and drills causing microcracking in induced stress weakened zones Drainage Water seepage due to blocked ditches or ineffective toe drains mismanagement Each factor contributes to localized or systemic weakening of the slope and can trigger failures, especially when combined with natural destabilizers such as rainfall. Field Observations from Kalmakir. Field inspections and monitoring (2022–2024) revealed several critical observations:  Blasting conducted on non-standard grids led to overbreak in benches B5–B7.  Seepage water from haul roads accumulated at the slope toe, causing toe erosion. 63 YOSH OLIMLAR ILMIY-AMALIY KONFERENSIYASI in-academy.uz/index.php/yo  Seismic monitoring during equipment operation showed surface vibrations exceeding 5 mm/s in certain areas.  Excavation in the southern flank was conducted without advance reinforcement, resulting in 8–12 cm displacement over 2 months. Table-2 Summary of Geotechnical Data Parameter Typical Range at Kalmakir Bench height 12–15 m Slope angle (overall) 52–55° Rock mass rating 45–60 UCS (MPa) 30–70 Charge per hole 60–120 kg Peak vibration (PPV) 2.5–6.5 mm/s FEM Simulation Setup. Finite Element Modeling was conducted using PLAXIS 2D, simulating a slope section with layered rock mass and a benching system. The model aimed to represent typical stress and deformation conditions under: Controlled vs. uncontrolled blasting, phased vs. non-phased excavation, presence vs. absence of water at the toe. Table-3 Input Parameters Used Material Elastic Modulus (MPa) Cohesion (kPa) Friction Angle (°) Weathered Granite 2000 25 30 Fresh Granite 6000 55 36 Fill/Debris 500 10 25 Boundary conditions assumed roller supports on vertical sides and a fixed base. A Mohr- Coulomb constitutive model was used for rock masses. 64 YOSH OLIMLAR ILMIY-AMALIY KONFERENSIYASI in-academy.uz/index.php/yo r d e s Maximum horizontal a lu g Maximum horizontal a h displacement: 5.6 mm e r displacement: 16.2 mm P r I + + g g n n it Stress redistribution remained it Stress arching observed across s s a lB n o localized a lB g n bench faces d e llo r t n it a v a c x E No failure zones identified d e llo r t n ic n e u q e S Shear strain concentrated at o o slope toes C c : A n U o : B ir a n Factor of Safety (FoS): 1.35 o ir FoS dropped to 0.98 e a c n S e c S Scenario C: Same as B + Water Accumulation Pore pressure Displacement Predicted local failure contributed to base increased to 24.5 mm near B6 bench weakening Discussion and Engineering Implications. The modeling and field data clearly demonstrate that technogenic impacts can be equally or more hazardous than natural factors in certain conditions. Poor blasting increases the risk of overbreak and loosening of toe material. Improper excavation can create uneven stress zones, accelerating progressive failure. The presence of water at the slope toe multiplies these risks. Hence, a combined approach of improved blasting control, real-time vibration monitoring, and strict water management must be enforced in high-sensitivity areas. Technogenic factors play a critical role in slope deformation processes at o