Analysis of a Failed Basal Reinforced Embankment

An interesting failure involving geosynthetic basal reinforcement for embankments constructed on soft soil occurred at the Fresh Kills Landfill located on Staten Island, New York. The failure occurred in two stages, in May 1997 and April 1998, respectively. In this study, an attempt has been made to model the embankment from this case history using finite differenc software — FLAC (Fast Lagrangian Analysis of Continua, Itasca Consulting Group, 1996). The goal of such a study is to develop the Finite Difference model as an approximate design tool for future reinforced embankments. FLAC is a two-dimensional finite-difference code that uses an explicit time-marching method to solve governing field equations. The paper presents the results of such an analysis and compares them to the field results. Various stages of construction are simulated by applying different model loading conditions at different stages of the analysis. The development of excess pore water pressures with staged construction are captured by using the undrained mode of analysis. The limits of failure and zone of movement are found to be strikingly similar to the field observations. It is expected that the proposed research will contribute to the state of the art of analyzing and designing embankments reinforced with geosynthetics in basal layers.