Analysis of Slope Stability in Clayey Silt Under Steady-State Seepage and Research on Reinforcement with Anchor Plates

Clayey silt slopes are highly susceptible to instability under steady-state seepage, often exhibiting precursors to failure such as cracking at the slope crest. To address this cracking phenomenon under steady-state seepage conditions, a mechanical model characterizing the stability of clayey silt slopes was established. A MATLAB-based program was developed to implement the exhaustive method and derive the optimal solution. This study systematically analyzed the impacts of seepage-related parameters—including air entry value and pore size parameters—on slope stability and further optimized the design parameters of anchor plate support. Key research findings reveal that both the air entry value 1/α and pore size parameter n exert significant influences on the stability of three-dimensional clayey silt slopes under seepage conditions. Specifically, when the air entry value 1/α reaches 10 kPa, the slope safety factor reaches its minimum, rendering the slope most vulnerable to instability. Additionally, both the infiltration rate q and permeability coefficient ks can alter the pore water pressure distribution within the slope, thereby affecting its stability, with the magnitude of this effect varying substantially across different scenarios. Considering both slope safety and project costs, the optimal embedment depth ratio for single-row anchor plates should be KT = 0.8. Additionally, the stability of three-dimensional slopes can be enhanced by improving infiltration capacity and reducing slope angles. These findings provide theoretical guidance for anchor plate support in similar three-dimensional clayey silt slopes.