According to the degrading and soil mechanical characteristics of municipal solid waste (MSW)

a nonlinear constitutive model of total strain theory to describe the coupled effects of stress and degradation is established

on the basis of the stress-degradation model and isotropic compression characteristics and Duncan-Chang model. The mathematical expressions for volume and axial deformation of unit body changes with time in different stress states are given; and then methods for determining all parameters are also provided. Verification is implemented by simulating the stress-strain curves of MSW samples obtained from landfill and a few long term one dimensional compression tests in laboratory. The results indicate that the concept of the model is reasonable; the selection of parameters is relatively clear and the model is able to describe the constitutive relations of MSW with different degradation ages in a more comprehensive way

which can be used for analyzing the long term deformation of landfills.