Rock Fall Hazard Analysis for In-Pit Operations Potentially Impacting External Sensitive Areas

Abstract

Controlling rockfall-related risks is a requirement for safe pit operations and primarily mitigated through adequate bench geometry design and implementation. This paper presents a method for rockfall hazard analysis for in-pit operations potentially impacting external sensible areas, adapted from natural rockfall hazard analyses. The method considers the natural susceptibility to rockfalls pre-mining, rockfalls originated from bench failures, and those initiated as flyrock. Rockfall trajectory models are used to estimate the potential for blocks reaching exposed elements. Natural susceptibility to rockfalls and trajectories are used as a baseline on which to evaluate the potential effects of open pit operations on the environment and perceptions of communities in the area. The method is illustrated for an open pit in steep terrain in the Peruvian Andes at a feasibility level of study. The paper illustrates the flexibility for including considerations of pre-mining rockfall impacts on the external elements of interest, and for developing rockfall mitigation strategies that consider rock block velocities, heights, energies and the spatial distribution of trajectories. The results highlight the importance of considering the three-dimensional effects of the terrain on block trajectories, and how such insights allow for increasing the efficiency of resources available for rockfall protection structures.

Keywords

• rockfall
• hazard assessment
• open pit
• flyrock
• steep topography
• Peru