Keywords: municipal solid waste landfills, seismic design, site conditions, slope stability, dynamic soil-structure-interaction, finite elements.

Recent experience in developed countries characterized by high seismicity, like U.S.A and Japan, has shown that municipal solid waste (MSW) landfills are vulnerable to the seismic threat. Therefore, the environmental risk of a MSW landfill failure, expressed mainly by the consequences in its safety and serviceability, is strongly related to seismic risk. Despite the worldwide interest in the seismic design of MSW landfills there are certain topics that require more attention. Certainly, there is a need for more analytical and experimental research in this field in order to improve the seismic codes and become able to use more realistic numerical simulations.

Generally, the main concerns of the seismic design of a geo-structure, like a MSW landfill, should be the following: to evaluate the developed inertial accelerations, to assess its specific dynamic response, and to avoid potential instability on its slopes under seismic loading. However, as the seismic response of a landfill founded on soil is a typical dynamic soil-structure-interaction problem, the local soil conditions may determine not only the seismic excitation of the landfill, but its seismic response as well. Under these considerations, the aim of this study is: (a) to examine the impact of local site conditions on the seismic excitation and dynamic response of MSW landfills, and (b) to investigate whether this impact is determinative for the stability of landfill slopes.

Since modern numerical modeling techniques are capable of taking into account complicated geometries and material heterogeneity, efficient two-dimensional finite-element models have been developed, and linear or equivalent linear dynamic ground response analyses have been conducted. Parameters like the geometry, the properties of the soil or waste materials, and the characteristics of the seismic input motion are also examined. On the other hand, pseudo-static analyses and simplified procedures are performed in order to assess deformations and relate the proposed procedure with the standard code approaches for earthquake design of geo-structures.

The main findings of this study are the following:

• The seismic response of a solid waste landfill is a complex soil-structure-interaction problem, and local site conditions certainly play a significant role.
• Slope stability analyses based on the pseudo-static approach may be inadequate, while on the other hand, sophisticated dynamic slope stability analyses require not only experienced designers, but reliable data on a case-by-case basis as well.
• Current seismic codes seem rather incapable to cover fully the seismic design of MSW landfills, and other similar geo-structures, as they rather underestimate local site effects on ground shaking and slope stability.
• Proper seismic design of landfills should be performed on a case-by-case basis in order to be capable of taking into consideration, apart from the seismological conditions, the specific local site conditions and individual characteristics of each landfill.

1

E.L. Krinitzsky, M.E. Hynes, A.G. Franklin, "Seismic stability procedures for solid-waste landfills", Engineering Geology, 46, 143-156, 1997. doi:10.1016/S0013-7952(96)00108-1

2

N. Matasovic, E.Jr. Kavazanjian, R. Anderson, "Performance of solid waste landfills in earthquakes", Earthquake Spectra, 14(2), 319-334, 1998. doi:10.1193/1.1586003

3

E.M. Rathje, J.D. Brey, "One and two dimensional seismic analysis of solid-waste landfills", Canadian Geotechnical Journal, 38, 850-862, 2001. doi:10.1139/cgj-38-4-850

4

P.S. Seco e Pinto, "Dynamic analysis of solid waste landfills and lining systems" in ed. A. Ansal, "Recent Advances in Earthquake Geotechnical Engineering and Microzonation", Kluwer Academic Publishers, Chapter 9, 267-284, 2004.

purchase the full-text of this paper (price £20)

go to the previous paper
go to the next paper
return to the table of contents
return to the book description
purchase this book (price £135 +P&P)