Modelling the stress–deformation behaviour of municipal solid waste

Abstract

Conceptual modelling of municipal solid waste landfills is vital for prognosis of the long-term development and the assessment of risk potential. Landfills are considered as heterogeneous porous structures, in which flow and transport processes of gases and liquids are combined with local material degradation and mechanical deformation of the solid skeleton. This contribution deals with a constitutive model focusing on the mechanical deformation behaviour of the disposed waste dividing the solid material into two different fractions. The first fraction includes more grainy particles and has properties comparable with granular materials. The second fraction consists of more fibrous constituents having an important influence on the strength of the composite material. Stress–strain behaviour of the two fractions is modelled according to the theory of finite elasto-plasticity. Settlements generated by mechanical creep are also included in the model. The developed constitutive model is validated and calibrated on results from laboratory experiments applying genetic algorithms. Numerical analyses using the finite-element method show the capability of the presented approach.