The excavatability of the rock mass in a proposed open pit mine at
Globe-Progress has been assessed. The rock mass was initially evaluated by
determining variations in seismic velocity and by using the Revised
Size-Strength Chart. These two assessments should be performed during the
feasibility or early investigation stages of a project. A complete rock mass
excavatability assessment using a suite of geological and geotechnical
properties was then performed using three methods: RMR System; Modified
Rippability Rating; and a productivity estimation method. These three methods
should be applied during the investigation and design stages of a project.
The preliminary assessments show that most of the open pit rock mass is
expected to be rippable. The complete assessment differentiates weak, fair and
good rock masses within the open pit. Weak rock mass exists along the
Globe-Progress Shear zone, located along the northern and eastern pit walls and
also in the western pit wall where the Chemist Shop Fault is located are both
regions are expected to be diggable. Relatively weak rock mass also exists along
the Globe-Progress Shear axial hinge. The Globe-Progress Shear limbs are
generally fair to good rock where moderate to hard ripping should be
expected.