DEM analysis of stress state, fabric anisotropies and failure behavior in multi-layer stacked soilbags under geotextile-soil interlocking reinforcement

Abstract

The constraining effect of soilbags inhibits soil dilatancy, enhancing the strength and stiffness of the wrapped soil, and resulting in a considerable increase in bearing capacity. This study numerically investigated the macro-meso geotextile failure behavior, stress state, fabric anisotropies of wrapped soil and interlocking reinforcement mechanisms of three-layer soilbags under unconfined compression using the three-dimensional discrete element method (DEM). Macroscopically, the failure modes of wrapping geosynthetic depended on the friction between soilbags. With zero friction, failure initiated at the edges of the wrapping geosynthetic; whereas with a friction coefficient of 0.5, failure began in the middle and extended to the edges, showing a progressive failure pattern. Microscopically, the reinforcement of soilbag changed the contact pattern of the particle system from peanut-like to uniformly distributed ellipse. The load transfer to the boundaries caused the occurrence of wrapped soil expansion and geotextile rupture. Additionally, geosynthetic wrapping created an interlocking effect with the surrounding soils, forming a positive feedback to reinforce the wrapped soil before geotextile failure. New understanding on failure modes, stress states, interlocking effect and fabric anisotropies provides a solid foundation for designing reliable and stable soilbag geotechnical permanent protective structures.