REP16163

• Permit No: M1988112
• IBM Index Class Name: Report
• Doc Date: 7/14/1993
• Doc Name: SAN LUIS MINE PHASE II RAISE 1 DESIGN REPORT
• Media Type: D
• Archive: No

1
' San Luis Mine -Phase D, Raise 1 Design Report
acceptable limits. This factor of safety was computed for a rotational type of failure of the upstream
face of the embankment raise. This failure surface is depicted on Figure 4.1 as well as the lowest
factor of safety sliding wedge type failure surface.
The lowest factor of safety computed under static loading for the downstream face of the
' embankment in its raised configuration was 1.93. This failure surface involves a sliding wedge type
of failure with the VLDPE liner as the basal sliding plane and is depicted on Figure 4.2 along with
the lowest factor of safety rotational failure mode failure surface.
' 4.5 Dynamic Loading Conditions
' 4.5.1 Pseudostatic Stability
As per the approved Permit and Amendment, the pseudostatic seismic coefficient adopted for the
design of facilities with long-term exposure is O. i5g. The lowest factor of safety computed for any
' failure surface utilizing this seismic coefficient is 1.1. This factor of safety was calculated for a
rotational type failure of the upstream face of the raise as shown on Figure 4, 1. As shown on
Figure 4.2, the lowest factor of safety for potential failures of the downstream slope under a
pseudostatic coefficient of O.ISg is 1.5.
In terms of pseudostatic type of analyses, the earthquake loading is represented by an equivalent
static horizontal force acting permanently on the slope in a single direction out of the slope face.
The equivalent static force or pseudostatic seismic coefficient is selected to represent the "average"
sustained acceleration acting on the slope, rather than the extreme peak acceleration, but gives no
indication of the performance of the structure under peak loading. The pseudostatic coefficient is
generally selected to be in the range of 40 to 70 percent of the peak ground accelleration. Thus an
acceleration of .198g, which results in a factor of safety of one for a sliding blmck failure of the
downstream slope, is approximately equivalent to a peak ground acceleration of .28g - .SOg.
' Accelerations in excess of this range will result in a factor of safety which is less than one indicating
a failure. However, the method of analyses does not give any indication of the extent of failure or
damage to the structure.
The following section presents the dynamic stability of the embankment in its raised configuration
' in terms of the displacement or damage which could be expected for various levels of earthquake
ground motion.

luly~ 13, 1993 g SRK Project No. 14719