The study emphasizes landfill slope deformation and stability, pointing out that excessive instability can pose environmental and health risks. Existing knowledge lacks sufficient consideration for the complex time‐dependent behavioral and compositional changes while modeling numerical simulations. This paper aims to simulate a single clay‐geomembrane composite lined landfill slope deformation and stability using an advanced numerical approach. Slope angle, waste composition by integrating aging effects, configuration, and leachate level are considered as influencing factors. Thus, material properties are collected through a rigorous review process. A total of seven material models and eight submodels were developed using PLAXIS 2D by integrating Mohr–Coulomb, soft soil, and soft soil creep models to capture real waste composition and heterogeneity. Accordingly, results of vertical deformation rise from 0.44 to 1.41 m as the slope angle increases from 1V:4H to 3V:4H, but the factor of safety decreases from 1.82 to a critical 1.06, suggesting high instability at steeper gradients. Landfills with horizontal configurations offered better results than cellular filling. Because of age‐based heterogeneity and compaction inconsistency, cellular filling caused a 23% decrease in Fs and a 49% increase in vertical deformation. Aging showed that between fresh and 5‐year‐old waste, factors of safety decreased from 1.56 to 1.36, but after 5 years, waste properties maintained a smooth variation. PWP increased from 4.50 to 32 kPa as the leachate level rose from the drainage base to the ground surface, leading to a decrease in Fs from 1.60 to 1.26 and an increase in deformation from 0.75 to 1.12 m. In saturated conditions, long‐term creep deformation under sustained loading reached 1.55 m over 4.80 years, demonstrating the crucial role that time‐dependent analysis plays in landfill performance. The model is verified through backward analysis and comparative estimation with previously published research findings and ensures close agreement for its applicability for landfill slopes . In conclusion, this study highlights that landfill stability is controlled by changing material composition and behavior over time and elevated leachate conditions, in addition to slope geometry. By incorporating interface shear behavior, waste heterogeneity, and creeping into landfill design, PLAXIS 2D significantly enhances the performance prediction of landfill system analysis.
Dasho et al. (2026) studied this question.