Numerical Modeling of the Shear Response of a Composite Liner System with Municipal Solid Waste Degradation in Landfills

摘要

The dynamic coupled hydraulic, biodegradation and mechanical processes in conventional and bioreactor landfills significantly affect the in-plane shear response of the composite bottom and side liner system. Moreover, it is critical to investigate the in-plane shear behavior of the composite liner to maintain the integrity and serviceability of the liner systems. Previous studies on the shear response of composite liner systems have shown the shear response and importance of interface properties by considering only the influence of overburden stresses induced by waste mass in landfills. Till date, there is no study on the interface shear response of composite liner system that incorporates the effects of biodegradation of waste in landfills. In this study, a coupled hydro-bio-mechanical framework was formulated to investigate the in-plane shear response of the composite liner system in both conventional and bioreactor landfills as the MSW degradation progresses. The shear response of composite liner system was analysed both spatially and temporally in terms of the evolution of shear stresses and shear displacement along the liner interface. It was observed that the changes in the shear strength and stiffness of MSW due to biodegradation had a significant impact on the in-plane shear behavior of the composite liner system considered. In addition, the rate of biodegradation had considerable influence on the induced shear stresses and shear displacements along the liner interface. Overall, this study demonstrates the importance of assessing the in-plane shear response in identifying the stability of composite liner systems considering the influence of coupled processes in MSW landfills.