Hydro-Mechanical Evolution and Failure of Geobag-Stabilized Expansive Soil Slopes: Discrete Element Modelling and Experimental Validation

Rainfall infiltration in expansive soil slopes induces moisture redistribution, particle swelling, and shear strength degradation, thereby promoting shallow sliding and slope deterioration. Geobag reinforcement has emerged as an environmentally adaptable strategy to mitigate instability while supporting resilient and resource-efficient slope stabilization. This study develops a discrete element modeling framework integrating seepage-driven moisture transfer, moisture-dependent particle swelling, and strength degradation to investigate the hydro-mechanical behavior of geobag-stabilized slopes under rainfall. The model is calibrated with laboratory tests and validated against physical experiments with different slope angles and reinforcement layouts. Results show moisture accumulation initiates at the slope toe and propagates upward, while geobags delay infiltration and reduce internal moisture increase. Displacement evolution depends on slope geometry and reinforcement, with flat-laid geobags retarding deformation in gentle slopes and toe-stacked reinforcement more effectively suppressing sliding in moderate slopes. For steep slopes, reinforcement delays but cannot fully prevent large displacement. Distinct transitions among shallow progressive, attenuated, and block sliding are identified. The framework captures the coupled evolution of moisture migration, deformation, and failure modes, providing a mechanistic interpretation of geobag reinforcement effects and highlighting their potential as a sustainable and resource-efficient solution for resilient slope stabilization.