Dynamic Behaviour of MSW Materials Under Cyclic Triaxial Testing: A Case of Kahrizak Landfill, Tehran, Iran

Kahrizak landfill could be called the largest dumpsite not only in the Tehran province but also in the country. In some parts of this dumpsite, there are piles of municipal solid waste (MSW), with considerable height and very steep slopes, the stability of which is a constant matter of concern not only in static loading condition but also under dynamic loading. As this region is subjected to a high seismic activity, the dynamic properties of the dumped MSW would be necessary to perform stress–strain analysis and estimate the deformation in the body of a landfill cell. The estimation of deformations in a cell mainly at the crown of landfills is vital, as different types of facilities like gas drainage and leachate re-circulation systems are installed in landfills. This paper presents the results of some strain-controlled cyclic triaxial test on fresh MSW materials with a diameter of 100 mm to estimate the shear stiffness and damping of these materials. To normalize the estimated shear stiffness from laboratory tests, the measured Gmax from field continuous surface wave system was employed. The results showed that the damping ratio for MSW materials is considerably higher when soils. The results of this study showed that in the range of applied shear strains, G-reduction curve has a good agreement with the graph proposed in the literature; however, variation of damping ratio by shear strain seems to be lower than values proposed by these researchers.