Performance and Analysis of Arifiye Overpass Reinforced Earth Walls During the 1999 Kocaeli (Turkey) Earthquake - Reinforced Soil Engineering: Advances in Research and Practice - page 438

The most notable overall observation was the relative lack of significant
damage to the RE walls despite being subjected to strong ground shaking and
large displacements. In stark contrast to this behavior, a conventionally
constructed approach embankment located about 250m from the RE wall
suffered heavy damage during the earthquake, experiencing settlements of more
than 1 m. The good performance of the RE walls is thought to be particularly
meaningful in demonstrating the seismic stability of conventionally constructed
walls of this type.
3 NUMERICAL ANALYSES
Numerical analyses were performed to provide insight into the Arifiye Bridge RE
wall behavior and to calibrate our numerical model for a series of parametric
analyses to be performed later. The commercially available program FLAC (fast
Lagrangian analysis of continua) was used for these analyses. FLAC uses an
explicit finite-difference scheme to solve static and dynamic problems. Although
some aspects of RE wall behavior are three-dimensional, the aspects important to
this study are captured with two-dimensional analyses, and thus the two-
dimensional version of FLAC (FLAC2D) was used and a plane strain condition
was assumed.
The FLAC program offers several structural elements such as cable
elements, beam elements, and pile elements to represent structural members in
geotechnical engineering problems. Interface elements are provided to define the
interaction of the structural elements with the immediate media around (Itasca
Consulting Group, 2000).
For this study, cable elements were utilized to model the strip
reinforcements. Cable elements are defined by their axial strength and axial
stiffness properties as well as the interface characteristics between the cable and
the surrounding media. Facing panels were modeled using beam elements where
the flexural stiffness properties are formulated. Interface elements are used to
define the connectivity between the facing panel and the backfill soil.
The analyses considered the pre-earthquake condition of the wall by
modeling the wall construction in a static condition, as well as a dynamic phase
that stimulated earthquake shaking. The static analysis was accomplished in
stages stimulating the sequence of construction, followed by the dynamic phase
where the model was excited with a recorded acceleration time history from the
1999 Kocaeli earthquake. Details of the analysis procedure and results are
discussed below.