Modelling the Mechanical Behaviour of Municipal Solid Waste for an Engineered Landfill Using Viscoelasticity and Other Established Concepts

Abstract

The stabilization process in municipal solid waste (MSW) is inherently complex. In the short term, waste has an immediate elastic response due to surcharge loading. Long-term stabilization involves a secondary mechanical settlement phase and a thermally dependent biodegradation phase. It can be difficult to distinguish the time-dependent behaviour between these components.Two composite compressibility models were developed to simulate settlement. One model was based on Marques et al. (2003) and another on viscoelasticity. Both models achieved correspondence with the field data for short-term and long-term settlement. Good consistency was achieved for the parameters across both optimized models. The parameters achieved for both model types are all within acceptable limits from literature for MSW. The Marques et al. (2003) based model allowed a more rigid transition between immediate elastic response and time-dependent settlement. The viscoelastic model proved more consistent in reproducing the transition patterns seen in real MSW displacement. iii ACKNOWLEDGEMENTS

Development of a Coupled Thermal-Mechanical-Biological Model to Simulate Temperatures and Settlement at a Landfill in Ste Sophie, Quebec

“…compares the settlement parameters from this model with those published byMcDonald (2018). With the exception of EDG, the values are reasonably close (within 7.8%).…”

“…(Van Geel and Murray, 2015). When installed, bundles 11 and 12 were not placed in the same two vertical columns as the other bundles and were shifted towards the centre of the landfill to allow for coverage under the side slope (McDonald, 2018). Therefore, only data from bundles 3-8 was considered to finalize EDG.…”

“…Because of insufficient data to implement a correct loading sequence, the initial compaction behavior is not present in the FEM model. Therefore, a starting value of Young's modulus was included byMcDonald (2018) to account for the compaction of the waste in the field. To match the trend seen in…”

“…and settlement parameters fromMcDonald (2018) were used. The model results were similar to the temperatures simulated byBerquist (2017) and the settlements simulated by McDonald (2018) but not the same as several improvements were made to the model and the model is now fully coupled.…”

“…In addition, the biodegradationinduced settlement in the mechanical model is directly linked to the temperatures and expended energy simulated in the thermal model. This model, with the parameters fromBerquist (2017) andMcDonald (2018), was used as the initial conditions for the optimization simulation.…”