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Seismic Evaluation of a Tailings Dam Using Uncoupled and Fully Coupled Soil Constitutive Models

Tailings and Mine Waste Conference (2023 : Vancouver, B.C.); University of British Columbia. Norman B. Keevil Institute of Mining Engineering

The Henderson Tailings Storage Facility (TSF) is an active facility located near Parshall, Colorado, consisting of two dams – 1 Dam and 3 Dam. The upstream method of construction has been used for tailings deposition since the mid-1970s. This paper presents the results of the seismic evaluation of 1 Dam using multiple constitutive modeling methodologies: an uncoupled Mohr-Coulomb approach and a fully coupled critical state-compatible PM4Sand/Silt approach. The analyses were completed to study the seismic response of the tailings embankment under the Maximum Design Earthquake (MDE) with a return period of 10,000 years. The numerical analyses showed that the results of the fully coupled, effective stress PM4 models were generally consistent with the uncoupled Mohr-Coulomb models. The PM4 models have the capability to estimate the generation of excess pore water pressure and onset of soil liquefaction during the application of the input ground motion. Subsequent zones of tailings materials that were prone to soil liquefaction or strength loss were identified based on two criteria: 1) excess pore water pressure ratio; and 2) shear strain in the PM4 modeling. This study provides valuable insights into the methods used to estimate seismic response of the Henderson TSF and highlights the importance of using properly calibrated advanced constitutive modeling methodologies to capture the complex response of tailings materials under seismic loading. The fully coupled models were capable of capturing the hysteretic soil response, including stress-strain response and accumulation of plastic shear strains, providing confidence in the predicted modes of deformation and informing the design and management of the facility.

Text

2023-12-08

Attribution-NonCommercialNoDerivatives 4.0 International

http://hdl.handle.net/2429/86809

Unreviewed

http://creativecommons.org/licenses/by-nc-nd/4.0/