Failure of Geotextile-Reinforced Vertical Soil Walls with Marginal Backfill

Twenty-seven physical models of geotextile-reinforced vertical walls with a range of backfill soils were tested to failure in the geotechnical centrifuge. The models were used to assess the effect on wall stability of the properties of the backfill, which ranged from clay through sand, with combinations of the two in varying ratios. The effects of the reinforcement length and of reinforcement overlap on stability also were assessed. Geotextile-reinforced clay backfill retaining wall models reached an equivalent full-scale height as great as 17.7 m for the wall geometries, clay, and geotextile used in these models. None of the models failed by geotextile pull-out, which typically is assumed to be the controlling mode of failure in walls with clay backfill and is perceived as a primary disadvantage to using such marginal soil as backfill. Development of failure was different for clay backfill walls than for backfill walls with clay-sand mixes, in large part because of prefailure deformations that were heavily influenced by the backfill properties. These deformations also played a very significant role in failure. Wall failure by sliding could be predicted adequately by using simple limit equilibrium analysis if realistic soil strength parameters were used in those analyses.