PREDICTING SETTLEMENT OF CHEMICALLY STABILISED LANDFILLS

Abstract

This paper presents the findings of numerical analyses to predict the vertical and horizontal displacements of closed landfills under surcharge load with and without treatment by chemical admixtures. The finite element program, PLAXIS, has been used to evaluate the settlement of a landfill model. The soft soil creep model is used for this analysis. Five layers of solid waste are considered for the landfill to evaluate the effect of depth of stabilisation on settlement of landfill model. Treated and untreated municipal solid waste (MSW) parameters are obtained from the results of anextensive laboratory program performed on MSW samples in this research. The settlement of the landfill model 10 and 20 years after applying the surcharge load for different fly ash-quicklime contents and various depths of improvement is estimated. Results indicate that treatment of MSW reduces the vertical displacement of the landfill model under surcharge load significantly. This reduction is more with higher depths of improvement.The finite element results have been validated based on results of triaxial tests conducted in the laboratory on the treated municipal solid waste.