A Refined Gradation‐Based Suffusion Model for Soil–Rock Mixtures in Slope Stability Analysis

ABSTRACT Existing suffusion models inadequately characterize soil grading parameters, failing to quantify particle changes and comprehensively map soil property evolution during erosional processes. This paper presents a suffusion model for soil–rock mixtures, enabling quantitative assessment of mass changes across different particle groups. The model integrates four key computational modules: the seepage control equation, critical conditions for soil particle movement, particle grading equations, and porosity relationships. The feasibility of the proposed model for predicting mass changes in particle groups during the suffusion of soil–rock mixtures was subsequently validated through two seepage tests. Finally, a comprehensive stability analysis of the soil–rock mixture slope was conducted using the refined gradation‐based suffusion model. This analysis evaluated volume water content, pore water pressure, particle gradation, and factor of safety. The validations between experimental results and the analysis method confirm the validity and robustness of the formulated suffusion model. This study realizes the quantitative analysis of each particle group during the process of suffusion of soil–rock mixture, and further predicts the stability of soil–rock slope during the suffusion process.