Predicting Active Non‐Limit Earth Pressure on Retaining Structures With Narrow Backfill: A Stress Characteristics Approach

ABSTRACT This study proposes a theoretical framework for predicting active non‐limit earth pressure on retaining structures with narrow backfill, based on the stress characteristics method (SCM) integrated with a displacement‐dependent shear strength mobilization model. The method captures the progressive transition from at‐rest to active states while incorporating geometric constraints, soil cohesion, and interface behavior. Validation against reduced‐scale model tests shows strong agreement in pressure distributions, failure mechanisms, and total thrust evolution. Compared to existing analytical solutions, the proposed approach improves prediction accuracy without relying on predefined failure surfaces and extends applicability to cohesive soils. Both experimental and theoretical results demonstrate that the critical wall displacement required to fully mobilize active earth pressure is largely insensitive to the backfill aspect ratio, enabling simplified mobilization modeling for narrow backfill conditions. Parametric analyses further reveal that narrower backfills result in lower active earth pressure throughout the non‐limit process and shift the application point of the resultant force upward due to enhanced soil arching, while cohesive soils exhibit a downward shift associated with tensile crack development. These findings provide a robust and practical tool for designing retaining structures in spatially constrained environments, improving both prediction accuracy and design efficiency.