Improving Slope Stability Analysis: The Role of Calibrated 3D Numerical Models

Abstract

Best mining practices indicate that when dealing with large/deep slopes or slopes excavated in complex geological-structural environments, sophisticated numerical models may be required for stability analysis. These models must be meticulously calibrated, drawing upon historical data to accurately reflect the behavior of the slope over time.

With the experience of the different failure modes available at an open pit mine, the design of the future planned pushback can be carried out with considerable confidence. Back-analyses play an important part in the confidence of the slope design.

Zaldivar mine is located at an average elevation of 3,000 meters above sea level, located 1,400 km north of Santiago and 175 km southeast of the city of Antofagasta, in the region that bears the same name.. Past failures at Zaldivar mine display a classical failure mechanism i.e., large scale wedge/planar failures and circular arc failures in highly altered weak rock. A series of 3D numerical models have been used to evaluate the response of one of its walls located in a weak or highly anisotropic rock environment.

This article aims to present the developed calculation used for conducting calibration models. It relies on the implementation of local 3D models, which have served as a foundation for comprehending the diverse range of parameters and their influence through back analysis development for a failure that occurred in 2015.

By utilizing 3D distinct element software, high resolution meshes, incorporating a novel anisotropic constitutive model, and assessing the influence of geological discontinuities, this study seeks to show the significant role played by calibration models in supporting the characterization process and slope design when a series of push backs geometries are proposed.