Simplified Method for Consideration of Soil Arching in 2D Limit Equilibrium Slope Stability Analyses of Pile-Stabilized Embankments

Vertical piles are commonly used to enhance embankment slope stability through their lateral load capacity that provides resistance against destabilizing earth pressures. Typically, in practice, the lateral resistance contributed by individual piles is estimated using 2D plane strain limit equilibrium analyses (LEA), based on the available lateral load capacity of a single pile divided by the center-to-center spacing of the piles neglecting arching effects. However, when piles are closely spaced, soil arching can develop, limiting plastic soil flow between piles. Under these conditions, the row of piles tends to act more as a continuous plane strain stabilizing wall. Neglecting this mechanism leads to overly conservative designs. Current practice employs a decoupled iterative method using 2D LEA and p-y analyses of single piles, which inadequately captures arching effects. This paper presents a modified computational procedure incorporating soil arching into the 2D limit equilibrium framework. The approach employs finite element analysis to estimate additional lateral resistance due to arching between closely spaced piles. An illustrative example demonstrates the enhanced slope stability achievable by accounting for soil arching effects within pile-stabilized embankments.