A laboratory study on the MSW mechanical behavior in triaxial apparatus

Mehran Karimpour-Fard; Sandro Lemos Machado; Nader Shariatmadari; Ali Noorzad;
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Shear strength characterization of MSW materials is a mandatory task when performing analyses related
to landfill design and landfill geometry improvements. Despite the considerable amount of research
focusing on MSW mechanical behavior there remain certain aspects which are not completely under-
stood and deserve attention in particular the case of the undrained behavior of MSW. This paper presents
the results of a comprehensive laboratory testing program using a large-scale triaxial apparatus at the
Federal University of Bahia, Salvador, Brazil. The effect of factors such as confining pressure, unit weight,
fiber content, rate of loading and over-consolidation on the MSW mechanical response were investigated.
Tested samples presented typical MSW shear/strain curves (concave upward) in all the tests, despite the
pore water pressure reaching levels almost equal to the confining pressure. The obtained results show
that increasing confining stress, unit weight, loading rate, fiber content and over-consolidation lead to
an increase in the MSW shear strength. The importance of the fibrous components in the waste behavior
is highlighted and graphs showing the variation of the MSW shear strength with fiber content in different
drainage conditions are shown. The authors believe these results could be of interest to many companies,
especially considering the new trend of plastic material recycling (prior landfilling) for energy recovery