Development and evaluation of a phase relationship for MSW

Compression is one of the most important mechanical aspects of behaviour of municipal solid waste (MSW) which concerns stability, deformation and structural performance in a landfill. Previous studies have shown that compressible particles play a significant role in MSW compression. Definition of the void ratio in classical soil mechanics theory may no longer be applicable for MSW material since high non-linearity between void ratio changes and vertical stress changes have been identified in compression tests. A new phase relationship for MSW has been developed to include the volume loss of compressible particles and this has been evaluated using onedimensional compression test data. The comparison between analytical and test results has demonstrated that the MSW phase relationship is capable of analysing the volume losses originated from inter-and intra-void ratio changes, in addition to the total volume loss of the MSW sample under different vertical stresses. Since it can isolate the volumetric change of compressible particles from the total volume loss, the MSW phase relationship is important when developing a constitutive model for MSW assuming elasto-plastic material behaviour, which couples the volumetric and shear behaviour.