Settlement Analysis of MSW Based on Constitutive Modeling Approach Sandeep K. Chouksey 1 , G.L. Sivakumar Babu 2 and Krishna R. Reddy 3 1 Research Scholar, Department of Civil Engineering, Indian Institute of Science, Bangalore 560012, India; email: choukseysandeep@gmail.com 2 Professor, Department of Civil Engineering, Indian Institute of Science, Bangalore 560012, India; e- mail: gls@civil.iisc.ernet.in 3 Professor, Department of Civil and Materials Engineering, University of Illinois at Chicago, 842 West Taylor Street, Chicago, Illinois 60607, USA, e-mail: kreddy@uic.edu ABSTRACT: A generalized constitutive model for municipal solid waste, based on the framework derived from critical state concepts and incorporating the effects of mechanical creep and time-dependent biodegradation, is presented. The model enables prediction of total landfill compression under incremental loading and with time. To illustrate the applicability of the model, settlements due to incremental loading of waste with time are predicted for typical landfill conditions and are compared with the predicted settlement results using other models reported in the literature. The proposed model predicts the total settlements in a range similar to the reported field-validated models in the literature. Effect of waste lift thickness on landfill settlement is also studied. INTRODUCTION For the past few decades, landfilling has become the most common practice for the disposal of municipal solid waste (MSW). Landfills are engineered structures consisting of bottom liners, leachate collection and removal systems, and final covers. MSW settles under its own weight and as external loads are placed on the landfill. External loads include daily soil cover, additional waste layers, final cover, and facilities such as buildings and roads. MSW settlement is mainly attributed to: (1) physical and mechanical processes that include the reorientation of particles, movement of the fine materials into larger voids, and collapse of void spaces; (2) chemical processes that include corrosion, combustion and oxidation; (3) dissolution processes that consist of dissolving soluble substances by percolating liquids and then forming leachate; and (4) biological decomposition of organics with time depending on humidity and the amount of organics present in the waste. Significant settlement occurs during and shortly after waste placement due to physical and mechanical processes, which is often referred to as primary settlement. Substantial additional settlement occurs at a slower rate over an extended period of time due to chemical and biological processes, which is often referred to as secondary settlement (Sharma and Reddy, 2004). 4176 GeoCongress 2012 © ASCE 2012