EGL Ref: 8983 8 October 2021 Page 19 File: TSF3 Stability Analysis Appendix Summary.docx.doc of the maximum acceleration ratio with depth of sliding mass from the top of embankments. The summary of the work is a range of ratios varying with depth of the sliding mass shown in Figure B14. For Storage 1A RL182 assessment a simplified approach has been taken for the application of amplification. Factors have been selected based on which third of the embankment the toe of the slide mass extends too, as summarised in Table B14. For slide masses which are with the top one third of the embankment height the full crest response has been applied. Makdisi and Seed (1977) indicates 0.62 to 1.0 for comparison. For slide masses which encompass the full height of the embankment the ratio is taken as the inverse of the crest amplification ratio selected, so that a slide of the full embankment would be applied the response spectra equal to that at the base of embankment. The ratio ends up being between 0.28 to 0.67. Makdisi and Seed (1977) indicates 0.20 to 0.62 for comparison. For slide masses which extend from the crest to between one third to two thirds of the embankment height the average of the top third and the bottom third has been taken, which results in values between 0.64 to 0.84. Makdisi and Seed (1977) indicates 0.3 to 0.9 for comparison. FIGURE B14: MAKDISI AND SEED (1977) MAXIMUM ACCELERATION RATIO WITH DEPTH OF SLIDING MASS SUMMARY FIGURE 1.0 0.62 0.90 0.30 0.62 0.20
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