Evaluating the stress–strain behavior of MSW with landfill aging

Abstract

Mechanical behavior of municipal solid waste (MSW) is of great importance due to many landfill slide failures in recent decades. MSW is the major structural element in landfill which is more complicated than soil owing to nonlinear and timedependent behavior. In this study to determine the effect of aging on MSW, 60 large-scale direct shear tests with dimensions of 300 × 300 × 150 mm were conducted on samples with three ages of fresh, 3 and 6 months. The tests had four vertical stress increments of 20, 50, 100, and 200 kPa under three different shear displacement rates of 0.8, 8, and 19 mm/min. After the evaluation of shear strength parameters, the hyperbolic model was presented to predict the stress-strain behavior of Kahrizak Landfill MSW as a sample of a disposal site in developing countries. Results indicate that shear strength of MSW samples increases with aging and also curves of hyperbolic function match with the results of direct shear tests. The hyperbolic model was first presented for soil with utilizing results of triaxial tests; however, applying results of direct shear tests for predicting the stress-strain behavior of MSW leads to a more accurate model due to the effect of fiber reinforcement and diversity in MSW composition.