Tailings and Mine Waste Conference

Slope stability model of the Questa rock pile : phase 2 Fredlund, Murray; Lu, Haihua; Feng, Tiequn


A slope stability analysis was performed for the mine rock pile located at Molycorp’s Questa Mine. The goal of this task is to provide a sensitivity analysis with respect to the influence of various input parameters on the slope stability model. The influence of a change in soil shear strength parameters as influenced by weathering factors was also investigated. A particular focus of the study is the examination of potential thin weak layers and their impact on the stability analysis. The weathering aspects of these weak layers and the resulting influence on stability will be determined through a sensitivity analysis. The 2D forward analysis for the Goat Hill North detailed conceptual model results in a peak shear strength factor of safety of approximately 1.4 and a large deformation shear strength factor of safety equal to 1.18. The probability of failure of a conceptual model similar to the Goat Hill North conceptual model displays a probability of failure greater than 4% only if the overall slope angle exceeds 37.5 degrees and the large deformation shear strength values are used in the model. For a weak layer to cause failure conditions the effective shear strength of the layer would have to drop to approximately 20-23 degrees. [All papers were considered for technical and language appropriateness by the organizing committee.]

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