Authors: Paola Torres, Jorge Macedo, Solange Paihua
Conference: Tailings and Mine Waste 2020
Date: November 15-18, 2020

ABSTRACT
This study presents the results for the dynamic effective stress analysis performed to evaluate the seismic performance of a center-line tailings dam in the South American Andes. To characterize the seismic demand at the project site, a probabilistic seismic hazard analysis (PSHA) was performed, producing deterministic-based and probabilistic-based seismic design criteria. The PSHA study shows that the project site is affected by both subduction interface and subduction intraslab ground motions. In addition, the PSHA study produced spectrally matched ground motions for the subsequent dynamic analyses.

This paper presents the 2D dynamic analysis of a tailings dam subjected to the maximum credible earthquake (MCE). The centerline tailings dam is planned to be raised up to 90-m high, and it will be composed by a starter dam and successive raisings. The dynamic analyses were performed with the software FLAC, using the UBCHYST constitutive model for materials that are not expected to produce large excess pore pressures, and the PM4Silt model for the materials that may generate excess pore pressures due to cyclic loading. The results suggest that there are no failure mechanisms by the end of the ground motions during the numerical simulations; however, there are considerable displacements. The results help to plan the overall operational management of the tailings facility.

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