Abstract
Managing the by-products of mining activities, which often hold no economic value, presents considerable challenges due to their potential environmental impact and stability concerns. Waste Rock (WR), the solid by-product of mining operations, must be removed to facilitate ore extraction. It is typically disposed of in Waste Rock Piles (WRPs) using various methods depending on project specifications. The blasting process involved in ore extraction produces WR with coarse, angular grains—some exceeding one meter in diameter—resulting in significant segregation and variability in geotechnical properties throughout the pile.
One promising approach to WR management is backfilling, where abandoned pits are repurposed as disposal areas. This method not only reduces waste visibility and land use but also aids in water management, making it a more sustainable option. Additionally, it can significantly cut operational costs and time. However, backfilling can lead to the formation of relatively high WRPs, making stability concerns even more critical in such cases.
Various numerical, experimental, and in-situ monitoring techniques are available to assess WRP stability. Deformation monitoring systems are commonly used for risk mitigation, allowing for stability assessments during and after construction. Despite substantial research efforts, existing studies often fail to fully capture the in-situ behavior of WR materials due to their inherent heterogeneity. Furthermore, a notable gap exists in integrating numerical modeling with field monitoring data, limiting the reliability of current predictive methods.
This research focuses on evaluating the geotechnical stability of high WRPs through advanced numerical modeling, real-time monitoring, and back-analysis of mechanical parameters. Using field data from the Canadian Malartic Mine’s WR backfill, the study integrates real-geometry advanced 3D constitutive modeling and iterative back-analysis, continuously validated by deformation monitoring. This approach enhances model accuracy and provides a robust framework for the safe construction and management of WRPs.
A central aspect of this research is the development of multiple real-geometry numerical models using Plaxis 3D, incorporating actual pile geometry, laboratory test results, and advanced constitutive models. The Hardening Soil (HS) model, calibrated with different laboratory data, is employed to simulate the non-linear stress-strain behavior of WR material. To refine geomechanical parameters such as stiffness, shear strength, and stress dependency, an iterative back-analysis approach will be implemented, integrating monitored displacement data to improve predictive accuracy.
The preliminary results reveal a strong correlation between mining production rates and instantaneous field deformations, indicating that increased waste deposition directly affects displacement patterns within WRPs. Additionally, the study highlights the significant influence of pile geometry on deformation behavior. Variations in pile height and placement methods contribute to differences in settlement rates and shear deformations, underscoring the importance of considering construction techniques in stability assessments.
By integrating real-time monitoring with numerical back-analysis, this research establishes a more reliable framework for WRP stability assessments, enhancing predictive capabilities for large-scale mine waste storage. The methodology developed provides valuable insights for optimizing waste disposal strategies, improving operational safety, and mitigating environmental risks associated with WRP instability.