One- and two-dimensional seismic analysis of solid-waste landfills

The results from one-dimensional (1D) and two-dimensional (2D) dynamic resp onse analyses are compared to determine the reliability of the common pract ice of using 1D analysis to evaluate the seismic response of solid-waste la ndfills. Results indicate that 1D analysis generally provides a reasonably conservative estimate of the seismic loading and earthquake-induced permane nt displacement for deep sliding surfaces, such as along the base liner. Ho wever, caution is warranted for shallower sliding surfaces, where 2D topogr aphic amplification often results in larger values of seismic loading and p ermanent displacement than that predicted by 1D analysis. The 1D-2D analysi s comparison is not just a function of geometry, but is also dependent on t he different numerical formulations typically employed in each procedure (e .g., 1D wave propagation versus 2D finite element). Comparisons of accelera tions along the landfill surface indicate that 1D analysis consistently und er predicts the maximum horizontal acceleration (MHA) along the slope near the crest of the landfill. However, the seismic loading is shown to vary sy stematically with normalized cover slope length, with the maximum equivalen t acceleration for the full cover slope being about 40% of the peak acceler ation at the crest. Based on the results of this study, a simplified proced ure is proposed for scaling 1D results to account for 2D topographic amplif ication and cover slope averaging when evaluating the seismic performance o f landfill cover systems.