Volume change behavior of municipal solid waste at shallow depths within landfills: impact from variation of atmospheric temperature

For municipal solid waste (MSW) embedded in shallow depths within landfills, its temperature is susceptible to atmospheric temperature showing periodic change. Impact of temperature cycles on the volume change behavior of MSW remains unknown, the latter could impact the long-term stability of landfills and its further utilization as land resources. Conduct multiple thermal cycle experiments on waste soil under different constant low stress levels to investigate the effects of thermal cycling on its volumetric deformation behavior. Temperature-controlled triaxial test results indicate that temperature-cycling induced elastic and plastic volume changes of MSW were much larger than those of clayey soils. The accumulated plastic volumetric strain appeared to increase with the number of temperature cycles and gradually stabilized. The temperature-cycling induced volume change of MSW was dependent on stress level and MSW age, fresh MSW under a lower stress tended to yield a larger volume change. Notwithstanding this, temperature-cycling induced volume change of the aged MSW was still significant and cannot be ignored. Based on the triaxial test results, a method was proposed to estimate the thermoelastic-plastic compression index λT and thermoelastic compression index κT of MSW. A thermo-elastoplastic constitutive model in the form of λT and κT was developed, incorporating the number of temperature cycle, stress level, and MSW age. The feasibility of the proposed model was validated against the experimental results.