Authors: Paola Torres, Jorge Macedo, Solange Paihua
Conference: Tailings and Mine Waste 2023
Date: November 5-8, 2023

ABSTRACT

This study discusses advanced, effective stress analyses conducted to assess the seismic performance of a tailings storage facility (TSF) undergoing re-handling and reprocessing of tailings. The deposited tailings are expected to contain high residual mineral values, which has prompted the reprocessing operation. In this context, the seismic stability of the TSF is of interest as it is situated in a high seismicity area in the South American Andes, where subduction earthquakes are known to occur. The TSF is a legacy mining facility developed with the upstream construction method, and it has not been in operation for many years. Nevertheless, the high degree of saturation level of the deposited tailings makes it susceptible to liquefaction. Moreover, since the reprocessing operation involves excavation, dragging, and re-handling of tailings, the effects of earthquake-induced deformations must be considered for the operation planning.

The material strength and dynamic properties required to conduct effective stress seismic analyses have been estimated based on geotechnical site investigations and laboratory testing programs. The characterization of the deposited tailings under considerable layering effects and spatial variability is of particular interest. The field and laboratory results are used to characterize an advanced stress ratio-based model developed within the framework of bounding surface plasticity and consistent with the critical state framework. The assessment has been developed to estimate the TSF performance in terms of deformations under design ground motions representative of the seismicity in the South American Andes. Results from the analyses and how they inform the overall TSF planning are shared.

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