Pseudodynamic Stability Analysis of Landfill Veneer Cover Systems with Clogged Drainage Layer

Abstract

The accumulated water within the drainage layer of a final cover system of municipal solid waste (MSW) landfills is the foremost reason for the failure of final covers. This study adopts a pseudodynamic (PD) method to assess the seismic stability of landfill cover systems against direct sliding failure (DSF) and uplifted floating failure (UFF). The novelty of this study lies in consideration of the simultaneous action of hydrostatic, hydrodynamic, and seismic forces on the cover soil layer. The factors of safety (FS) against DSF (FSds) and UFF (FSuf) failures are evaluated by incorporating the effects of shear and primary (P) wave velocities, the phase difference between the seismic waves, soil amplification, time duration, and frequency of the earthquake. The influence of phase change on FSds and FSuf is examined, and the results are compared with those obtained by the pseudostatic (PS) method. The results show that the PD method yields a 29.11% increase in FSds and a 23.29% reduction in FSuf values compared with the PS method. The effects of horizontal seismic acceleration coefficient, slope angle, stability number, cover soil layer thickness, and height of landfill on FSds and FSuf are observed for different conditions of immersion ratio (Ir). Consideration of the soil amplification factor reduces the values of FSds and FSuf by 12.48% and 18.46%, respectively. The cover soil thickness (h) should be chosen between 0.047H and 0.067H, where the height of the landfill is H, to maintain safety against DSF and UFF modes for Ir = 0.3. Further, design charts are presented to compute the optimum thickness of the cover soil under earthquake loading conditions by targeting FSds and FSuf ≥ 1.15. Pseudodynamic (PD) stability analysis of veneer cover systems with accumulated water in the drainage layers is useful to model the behavior of landfill covers when subjected to various external loading conditions, which include earthquakes, heavy rain, and other environmental factors. The results of the analysis could be used to optimize the design of landfill covers to ensure their stability over time. The analysis could help engineers determine the appropriate thickness of the clogged drainage layer and other design parameters that ensure the long-term stability of the landfill cover. It could help assess the risks associated with earthquake loading or heavy rain and determine the probability of failure of the landfill cover system. These results could be used to plan and implement risk mitigation measures to reduce the potential for damage or environmental harm. In addition, it could be used to monitor the performance of landfill covers against direct sliding failure (DSF) and uplifted floating failure (UFF). This study proposed design charts that could facilitate practicing engineers to achieve safe, cost-effective, and reliable design of final covers of municipal solid waste (MSW) landfills. The findings of this study could be beneficial when standardizing the international design codes for the seismic stability of veneer cover systems.