Abstract: Landfill sites in China are characterized by high water levels and high air pressures. Despite the proposal of various stability evaluation indicators and grading standards in existing regulations and research, there remains a lack of systematic research on indicator weights and comprehensive risk assessment. Therefore, this study establishes a landfill instability risk assessment index system encompassing seven indicators across four categories: landfill geometric configuration, shear strength of waste soil, liquid and gas occurrence, and rainfall. Through parameter sensitivity analysis, a five-level classification (stable, relatively stable, basically stable, unstable, extremely unstable) is achieved, and set pair analysis is employed to construct the indicator correlation function. The comprehensive weights of the evaluation indicators are determined through the importance ranking of indicators, combined with parameter sensitivity analysis, engineering instability accidents, literature attention statistics, and game theory-based combination weighting. Subsequently, a comprehensive evaluation model for landfill instability risk is established by coupling the comprehensive weights of indicators with the indicator correlation function. This model is then applied to an actual landfill project, and the results are consistent with the actual monitoring data on site, thereby verifying the accuracy and effectiveness of the evaluation model.

Key words: landfill, stability, evaluation index system, set pair analysis, sensitivity analysis, combination weighting, risk assessment