3D seepage and slope stability assessment of a heap leach pad

ABSTRACT: Mining structures typically require 3D stability analysis as they exhibit strong three-dimensional effects due to topography, pore-water pressure variability, and geological structure. Specifically, mine heap leach pads require 3D stability analysis due to their narrow, steep slopes and translational failure mechanism caused by the weak surface associated with the liner system. The 3D stability of a heap leach pad was studied given a range of 3D seepage conditions. All analyses demonstrated large, translational failures due to the presence of the liner. As expected, the factor of safety dropped as pore water pressures increased at the site. Fully saturated conditions produced factor of safety values at or below 1, depending on the friction angle of the liner system. Dryer conditions associated with steady-state annual infiltration of 1250 mm, still demonstrated the substantial influence of pore water pressures on stability. Further consideration of the liner properties as well as the influence of heavy rainfall events on short-term pore water pressure conditions within the heap leach pad are necessary.