REP34115

• Permit No: M1988112
• IBM Index Class Name: Report
• Doc Date: 7/14/1995
• Doc Name: SAN LUIS MINE PHASE II RAISE 2 DESIGN REPORT VOLUME I OF II
• Media Type: D
• Archive: No

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' San Luis Mine Phase Q, Raise 2 Design
' downstream face with basal sliding along the embattktrtent-liner interface. The lowest yield
accelerations computed for sliding wedge and rotational type failures of both embankment slopes
' are given in Figures 10 and 11.
4.6.2.3 Dynamic Displacements
' Average displacements calculated by the COE method are in excellent agreement with those
' calculated by the Makdisi and Seed Method. Displacement calculations computed using the Corps
of Engineers (COE) method utilized the upper bound envelope curve, presented in graphical form,
for all natural earthquake records processed except the unusually large ground motions recorded
' during the 1971 San Fernando earthquake. The record processed included numerous records of
events with M > 7.0, and should also produce conservative results for the event considered.
Displacement calculations which were computed using the Makdisi and Seed method incorporated
the use of the displacement envelope for a magnitude 7.5 earthquake within graphs which are
presented for calculating displacements. Thus, the displacement calculations using the Makdisi and
' Seed method have incorporated an earthquake with a slightly longer duration than the MCE for the
site and the resulting displacements should be conservative. Displacements calculated using the
method of Ambraseys and Menu included several levels of probability and these results should be
' the most accurate for the San Luis facility.
A$ shown in the calculations included as Appendix G, displacements calculated utilizing the three
' . methods are in good agreement. Displacements calculated by the COE method were generally the
largest and reflects the upper bound nature of the correlation presented and uncertainty in the
' velocity associated with the design ground motion. Displacements calculated lby the Makdisi and
Seed method are higher than those calculated by the Ambraseys and Menu metttod and reflect the
' use of the chart for a magnimde 7.5 earthquake. Displacements calculated fora 16 percent
probability of exceedence using the method of Ambraseys and Menu are in good agreement with
those calculated by the COE and Makdisi and Seed methods.
' For a peak ground acceleration of 0.6g arising from a M=7+ earthquake, the displacement along
' the critical potential failure surface for the downstream face is estimated to be on the order of 1-3
ft. Under the same loading conditions, the displacement along the critical downstream face
rotational failure surface depicted on Figure I1 is estimated to be on the order of 1 to 1.5 ft. For
' the upstream face of the embankment raise and PGA=0.6g, the displacement estimated for both the
critical circular failure surface depicted on Figure 10 is on the order of 1 to 1.5 ft.

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