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BRAY, RATHJE, AUGELLO AND MERRY D Seismic Design for Lined Solid-Waste Landfills <br />226 GEOSYNTHETICS INTERNATIONAL S 1998, VOL. 5, NOS. 1-2 <br />fromdamage, suchasasacrificial low-friction slip surface to concentrate deformations <br />awayfromcritical components, areuseful. Andersonand Kavazanjian (1995)andBray <br />et al. (1993)give guidance with regard to evaluating seismic stability, but considerable <br />engineering judgment is still required. <br />This simplified approach is most appropriate when the waste fill dynamic response <br />characteristics indicate that it will not be close to a resonance condition with the input <br />motions (i.e.Ts >Tm ). When close to resonance, one would need to incorporate signifi- <br />cantconservatism withthesimplified approach, andthismaynotbeeconomical. Asite- <br />specific dynamic analysis could be used to calculate the base and cover equivalent ac- <br />celeration-time histories, and these time histories could be double integrated to <br />calculate displacements,U, at selected values of ky to construct a plot of U versus ky . <br />Such a plot is useful in evaluating a landfill’s potential seismic performance. <br />3.3.5 Example <br />Base sliding . Analyze the base sliding stability for a 35 m high landfill founded on <br />rock for a Mw = 7 strike-slip earthquake at a distance of12 km. Slope stability analyses <br />indicate that the yield acceleration coefficient for sliding along the base liner is 0.15. <br />1. Estimate the median MHA ,Tm ,andD5-95 values of the rock ground motion: <br />MHA Rock <br />0.33g (Figure 2a) <br />T m <br />0.52 s (Figure 2b) <br />D 595 <br />14 s (Figure 2c) <br />2. Calculate the seismic loading,MHEABase . An average Vs profile might be approxi- <br />mately 120m/s at the waste surface, approximately 275 m/s at a depth of30 m, and <br />approximately 375 m/s at a depth of 60 m. Hence, a reasonable weighted average <br />of Vs for a 35 m high waste fill would be approximately 200 m/s, with Ts =4H/Vs = <br />0.7 s, and Ts /Tm =1.3: <br />MHEA Base [(MHA Rock)(NRF)]<br />0.43 to 0.58 (50%16% exceedance) (Figure 6) <br />NRF <br />1.05 for MHA Rock <br />0.33g (Figure 6) <br />MHEA Base <br />(0.33g )(1.05)(0.43 to 0.58)<br />0.15g to 0.20g <br />3. Estimate the seismically induced permanent displacements: <br />k max <br />MHEAg <br />0.15 to 0.20, and k y <br />0.15 (given), so kyk max <br />0.75 to 1.0 <br />Uk max D 595 <br />0 to 4 mm/s (from Figure 11, using 50 and 16% exceedance lines) <br />U <br />(0to4mm/s)(0.15)(14s)=0to8mm(i.e.smalldisplacements) <br />3.3.5 Example <br />Base sliding .Analyze the