Slope Stability of Landfill Using Probabilistic Approach

The major parameters governing municipal solid waste (MSW) slope safety and stability are the unit weight, cohesion, and friction angle. Variability associated with these parameters is a major concern in landfill design because it affects the stability of slopes during the short and long-term operation of landfills. The current study focuses on slope stability of landfills for two different cases (homogeneous and non-homogeneous landfills) based on the data collected from the past literature on Indian landfills/dumpsites. Case I: Homogeneous case, where all data can be considered homogeneous and case II: non-homogeneous case, the entire data are splitted into fresh waste (<1 year), medium degraded waste (1 to 3 years), and old waste (>3 years). Based on the available data, statistical analysis is performed for both cases, and ranges are defined in terms of mean, standard deviation, and coefficient of variation for the estimation of a factor of safety (FOS) using slope/W module for the various slope inclinations (1:2 and 2:3). It was noted that the above slopes satisfy the minimum criteria (1.50) for FOS. Reliability index (β) and probability of failure (Pf) are computed based on the FOS values. The first-order reliability method (FORM) is used to calculate the probability of failure (Pf). The FOS and probability of failure give better results in non-homogeneous landfills for both slopes.