COMPLIANCE INFO_JTD 12/4/2025 - Laserfiche WebLink

Home Browse Search

BRAY, RATHJE, AUGELLO AND MERRY D Seismic Design for Lined Solid-Waste Landfills 225GEOSYNTHETICS INTERNATIONAL S 1998, VOL. 5, NOS. 1-2 MHATop to account for2-Deffects. Forseismic loading ofthe entire cover slope, use MHEACover =0.65MHATop to account for incoherence. 3.3.3 Calculate Seismic Stability Calculate Newmark seismic displacements (or calibrated pseudo-static FS). (a) Seismically induced permanent deformation analysis: 1. Calculate the yield acceleration coefficient,ky , for potential sliding masses (i.e. seismic coefficient that resultsin apseudo-static FS = 1.0).Estimate ky at thecov- er and base for generalized landfill systems using Equation 1and 2, respectively. Otherwise, use a limit equilibrium slope stability program which has a method that satisfies full equilibrium, such as Spencer, Morgenstern and Price, or Gen- eralized Janbu. The unit weight and strength of the municipal solid-waste and geosynthetic interface strengths can be estimated using the summary data pro- vided in Sections 2.4 and 2.5. 2. Base sliding: Estimate the displacements,U, at the base given the estimates of ky /kmax ,kmax ,andD5-95 (Figure 11). Note that kmax =MHEABase /g for base sliding. Use the median and 16% probability of exceedance lines. 3. Cover sliding: Estimate the displacements,U, at the cover given the estimate of ky /kmax and Mw (Figure12).Use kmax =MHEACover /g,withtheappropriate MHEACover value for either localized cover sliding or sliding along the entire cover. 4. Other cases: Estimate range of displacements,U, from Figure 11, given the MHEA estimate from Figure 6 where H is equal to the depth of sliding. (b) Alternative calibrated base and cover pseudo-static stability analyses: Select the limiting displacement level with the corresponding reduction factor,R, for base and cover sliding, with R =ky /kmax at the selected displacement. Use RC = 0.6, 0.8, or 1.0 for the limiting cover displacements of < 300 mm, < 75 mm, or < 20 mm, respectively. Use RB = 0.6, 0.8, or 1.0 for limiting base displacements of < 150 mm, < 50 mm, or < 10 mm, respectively. Apply (RC )(MHEACover)/g as the seis- mic coefficient,k, to a shallow cover failure mass and calculate the pseudo-static FS. For base sliding, use k =(RB )(MHEABase)/g.IfFS > 1, displacement is likely to belessthanthecorresponding limiting displacement value (i.e. there isa 10%prob- ability of exceedance). 3.3.4 Evaluate Seismic Stability Given the seismic displacement estimates (i.e. small (< 25 to 50 mm), moderate (< 150to 300mm), orlarge (> 0.3to 1m) displacements), evaluate theability ofsensitive landfill wastecontainment componentstoaccommodate thislevelofdeformation. Pen- etrations (e.g. vents and leachate sump risers) and changes in geometry (e.g. side liner to base liner transition) are potentially vulnerable. Cover systems are more easily re- paired than base systems, and hence, they have a lessstringent designlevel. Theconse- quences offailure and conservatism ofthe hazard assessment and stability analysis are important designconsiderations. Defensive measures that “shield” critical components Calculate Newmark seismic displacements (or calibrated pseudo-static FS). 3.3.4 Evaluate Seismic Stability