Determination of the geosynthetic reinforcement stiffness to be
used in design procedures is complicated because it can be affected
by soil confinement, time under load, strain level, and temperature.
Walters et al. (2002) showed that in-isolation creep stiffness data are
sufficient in estimating reinforcement loads from strain measurements
for geogrids and most woven geotextiles.
Baker and Klein (2004) developed a design approach that has
a wide range of design options between wrap-faced GRS walls and
conventional nonreinforced retaining structures to fulfill the need to
consider the effects of wall face properties, as well as reinforcement
and the soil. In this approach, the limit equilibrium design requirements
for safety factors are imposed at all relevant points. Participation
factors that vary according to the type of wall are used to
incorporate the interaction between the wall and reinforced soil in the
design. Tensile force distribution in each reinforcement layer and
soil pressure, shear force, and moment distributions in the wall are
established, allowing the design of suitable GRS wall components.
Klar and Sas (2009) developed the work of Baker and Klein (2004)
by optimizing the relative displacements between the reinforcement
layers and the wall, and resolving the participation factors. The
parametric study utilizing this solution showed that when the wall is
relatively stiff compared with the reinforcement, forces in upper
reinforcements are affected by the lower levels, whereas for a wall of
low stiffness, the solution is not dependent on reinforcement pullout
stiffness. This study, along with the previous two studies mentioned,
indicates the necessity of incorporating the role of the wall facing to
design procedures.