2009/2010 Stage 2 Problem Statement - SME

2009-2010 SME/NSSGA Student Design Competition
2.5. Assignment
As the mining engineer, your responsibility is to specify the inclination of the quarry pit walls
based on the information given above. For your convenience, the Engineering Geologist who
collected the discontinuity data has subdivided the quarry into engineering ‘sectors’, as seen
below in Figure 2.
According the permit, as presented in Phase One, safety benches are required to be a minimum
of twenty five feet with a maximum bench height of one hundred feet. The maximum bench face
slope is 0.2H:1V. The pit floor can be no lower than 250 feet m.s.l.
Complete an analysis of your mine design and determine the most appropriate final highwall
design for the data given, for the sectors stated below. The bench angles should be based on
kinematic analyses while the overall pit slope angle is a function of the strength of the rock mass.
Inter ramp angles should be based on the results of the overall pit slope angle as appropriate. In
order to conserve time and so that you can focus on other aspects of the design, your engineering
manager has completed the kinematic analysis for sectors 1, 3, 5 and 6. The maximum safe
bench angles are 68, 75, 66, and 90 degrees; respectively. This does not take into account the
overall slope angle, which needs to be determined by your team. An appropriate safety factor for
static conditions is 1.3 given the reliability of the geotechnical data available (and the perceived
risk associated with that safety factor). Seismic loading need not be addressed.
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