Required strength of geosynthetics for reinforced 3D slopes in cohesive backfills with tensile strength cut-off

Abstract

In extant studies, most of the stability analyses of geosynthetic-reinforced slopes focused on two-dimensional conditions using the Mohr-Coulomb (M-C) failure criterion to describe the strength of backfills. However, in reality, all failures of slopes indicate a somewhat three-dimensional (3D) feature, and the M-C criterion is observed to overestimate the tensile strength of cohesive soils. To partially remedy this shortcoming, the concept of tensile strength cut-off is adopted to include the actual tensile strength of backfills in the yield envelope, and a kinematic approach is presented to evaluate the required strength of geosynthetics for 3D reinforced slopes in cohesive backfills. A 3D rotational mechanism of collapse that is associated with the strength envelope with tension cut-off is developed. The amount of required reinforcement is evaluated and listed as a dimensionless coefficient. The results indicate that the inclusion of the 3D effect and soil cohesion can lead to substantial savings in terms of the reinforcement to be made. In addition, a higher amount of reinforcement is required when the effect of tension cut-off is considered; this effect is more distinct for backfill with a higher amount of cohesion.