South Peak is a 7-Mm3 potentially unstable rock mass located adjacent
to the 1903 Frank Slide on Turtle Mountain, Alberta. This paper presents
three-dimensional numerical rock slope stability models and compares
them with a previous conceptual slope instability model based on
discontinuity surfaces identified using an airborne LiDAR digital
elevation model (DEM). Rock mass conditions at South Peak are described
using the Geological Strength Index and point load tests, whilst
the mean discontinuity set orientations and characteristics are based
on approximately 500 field measurements. A kinematic analysis was
first conducted to evaluate probable simple discontinuity-controlled
failure modes. The potential for wedge failure was further assessed
by considering the orientation of wedge intersections over the airborne
LiDAR DEM and through a limit equilibrium combination analysis. Block
theory was used to evaluate the finiteness and removability of blocks
in the rock mass. Finally, the complex interaction between discontinuity
sets and the topography within South Peak was investigated through
three-dimensional distinct element models using the code 3DEC. The
influence of individual discontinuity sets, scale effects, friction
angle and the persistence along the discontinuity surfaces on the
slope stability conditions were all investigated using this code.