Modeling the Time-Dependent Behavior of Geosynthetically Reinforced Soil Structures with Cohesive Backfill - Reinforced Soil Engineering: Advances in Research and Practice - page 77

interface elements should, without modification, be directly applicable to the
analysis of geosynthetically reinforced structures with cohesive backfill.
9 CONCLUSIONS
The modeling and finite-element analysis of geosynthetically reinforced soil
structures with cohesive backfill have been critically reviewed. The following
points pertaining to this subject are particularly significant:
The use of a cohesive backfill has the potential of complicating the problem
in that a coupled deformation-pressure formulation may be required. The
associated finite-element analysis requires the use of mixed elements,
which must be selected judiciously.
In mathematically characterizing the cohesive backfill, the time-dependent
behavior of the material must be accounted for. The use of time-
independent constitutive models, though convenient and practiced in the
past, produces inaccurate results.
When the foundation underlying the structure is soft, the reinforcement will
be affected by settlement of the underlying soil. This has the potential of
necessitating a geometrically nonlinear analysis. In light of the fact that
material nonlinearities must also be accounted for in the analysis, the
associated computational effort typically increases rather sharply.
The spatial discretization of the reinforcement is relatively straightforward.
Complications may arise if the reinforcement is also used to drain the
backfill. In this case, a semicoupled or uncoupled mixed element must be
used to represent the reinforcement.
The time-dependent response of the geosynthetic reinforcement must be
accounted for in a rational fashion. In particular, the constitutive relation
used must be general in scope, thus avoiding the past practice of a priori
assuming creep or relaxation response. The latter practice is not
consistent with finite-element analyses and typically precludes the
determination of a consistent incremental tangent modulus.
Provided that kinematically consistent formulations are used, a standard
interface element can be employed in the analysis of geosynthetically
reinforced soil structures with cohesive backfill. Failure to account for
the interaction between soil and reinforcement and between soil and
structural members such as facing can lead to inaccurate and possibly
spurious results.
Finally, the general observation that finite-element analysis of geosynthe-
tically reinforced soil structures must accurately simulate the actual or