Objectives:
This project aims to improve how excavation-induced rock mass damage is understood, characterized, and quantified in open-pit mines – an essential requirement for reliable slope stability analysis. When a pit wall is excavated, the rock mass experiences strength and stiffness degradation within the Excavation Damage Zone (EDZ). Current design practice typically represents this degradation using the Hoek–Brown Damage Factor (D), assigned a value between 0 and 1. However, research shows that the D factor can significantly influence stability outcomes and may not accurately capture rock mass behavior at low confinement. Laboratory testing and Synthetic Rock Mass (SRM) simulations indicate that Hoek–Brown D can overestimate strength loss, particularly in weaker rocks, potentially leading to overly conservative slope designs. Additionally, the extent and variability of damage within the EDZ remain poorly defined.
The project seeks to:
- Review the evolution, interpretation, and application of the Hoek–Brown D factor;
- Evaluate alternative methods for quantifying excavation-induced damage in stability assessments;
- Use laboratory data and scaled-up SRM models to address gaps caused by testing size limitations;
- Improve understanding of microfracturing in veined rock under deviatoric loading, building on prior LOP work;
- Extend past research on excavation-induced damage by simulating stress–strain responses across a wide range of rock strengths under realistic pit slope conditions;
- Compare Hoek–Brown D-derived strengths with SRM and strain-weakening model results;
- Develop practical guidelines for incorporating excavation damage and strength reduction into slope design;
- Validate the approach using field case studies with support from LOP and sponsoring companies.