Abstract
New displacement-softening and work-softening models were developed to describe the sliding of geosynthetic interfaces, such as those in landfill liners. The displacement-softening formulation is based on the assumption that strength reduction at the interface can be related to nonrecoverable (plastic) shear displacement. The model uses three relationships: (1) the peak strength envelope; (2) the residual strength envelope; and (3) the residual factor versus displacement ratio relationship, which is a nondimensional expression of the rate at which displacement-softening occurs. The displacement-softening model is accurate for shearing when the normal stress stays constant. When normal stress increases during shearing, the displacement-softening formulation overpredicts damage to geosynthetic interfaces. The work-softening model was developed to compute interface softening during conditions of increasing normal stress. This formulation is based on the assumption that the post-peak reduction in shear strength can be attributed to plastic shear work rather than plastic shear displacement. By calculating an equivalent plastic shear displacement for a given amount of plastic shear work, the work-softening model can be formulated using the same basic relationships as the displacement-softening model. The work-softening model significantly outperformed the displacement-softening model when simulating laboratory tests under conditions of increasing normal stress.
Published Version
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