PROBABILISTIC SLOPE STABILITY ANALYSIS OF MUNICIPAL SOLID WASTE LANDFILLS

Abstract

With increasing population and industrialization, the waste generation has also been increasing rapidly but due to land constraint we must use a particular area in a very effective way. For this we must put more waste on a site by increasing height and slope of landfill, hence slope stability analysis is required. MSW properties vary with space and time because of non-homogeneous nature, effect of overburden weight and amount of decomposition. This variability in geotechnical parameters leads to uncertainties in slope stability analysis. So, in this study, field data for unit weight and shear strength parameters are collected from 50 sites from the previous literature and the collected data is statistically analyzed for getting spatial variation of geotechnical parameters. Analysis of slope is done in two ways i.e., conventional analysis and probabilistic analysis. Limit equilibrium approach is the root for conventional methods, and it provides factor of safety value without considering variability of MSW properties while in a probabilistic method, the stability of the slope is render as chances of failure or reliability index. In probabilistic methods variation in parameters are considered with time and depth so that we can get more accurate results. That’s why probabilistic approaches are getting more importance now a days. To show the effect of spatial parameters such as COV and correlation distance, a slope is analyzed using finite element software OPTUM G2. The spatial variability of cohesion, frictional angle, and unit weight are modeled using random fields. The effect of these spatial variation of parameters on factor of safety and probability of failure are studied. With increase in correlation distance mean factor of safety decreases. Probability of failure increases with coefficient of variation and its value is more for high correlation distances.