Development of a seismic deformation analysis for the North Extension to the Tailings Disposal Facility at the Greens Creek Mine

ABSTRACT: Seismic loading is a potential trigger for liquefaction in regions with active seismicity. This study focuses on the development of a deformation model to assess the seismic performance of the proposed North Extension of the Tailings Disposal Facility (TDF) at Greens Creek Mine in Alaska, which is being constructed as a filtered stack (colloquially referred to as “dry stack”). Within the footprint of the TDF, a bedrock trough was identified during the field investigation program that contained weaker material, compared to similar foundation units located outside of trough. Based on the characterization of these materials, it is expected that they may be potentially liquefiable under seismic loading, therefore, it is planned to conduct a seismic deformation analysis to simulate the performance given an extreme earthquake event (i.e. 1:10,000 year event) and simulate the response of the critical foundation units using the constitutive model P2PSand. Given that the potentially liquefiable materials were only encountered within the trough, this assessment is based on a 3D deformation model built in FLAC3D to consider the spatial variability of the foundation geology and the geometric effects relating to the TDF geometry. This paper demonstrates a methodology to assess the potential for liquefaction by incorporating the available data and characterizing the critical soil units, which will contribute to informed decision-making in the design process.