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Seismic Responses of Geogrid Reinforced Wall with Tire Derived Aggregates (TDA)
Backfill using Reduced-Scale Shake Table Test
Les réponses sismiques des géogrilles renforcée mur avec des granulats de pneus dérivés (TDA)
en utilisant remblai d'essai à échelle réduite table vibrante
Xiao M., Hartman D., Ledezma M.
California State University, Fresno. USA.
ABSTRACT: This paper reports a preliminary shake table test on a reduced-scale mechanically stabilized earth (MSE) wall with tire
derived aggregates (TDA) backfill. The model MSE wall was built inside a steel-frame box on a one-dimensional shake table. The
wall was 1.5 m high, 1.2 m deep, and 1.5 m long, and five layers of TDA backfill were reinforced using geogrid. The 1989 Loma
Prieta earthquake excitations were scaled up based on a similitude law and were simulated by the shake table with target peak ground
acceleration of 1.62 g. Four types of seismic responses were measured: the accelerations in each reinforced backfill layer, the lateral
wall face displacements at the bottom, middle, and top of the wall, the dynamic vertical settlements of the wall, and the dynamic
vertical stresses within the backfill. These seismic responses were presented and analyzesd. Overall, the MSE wall performed well
with no apparent damage. The maximum horizontal deflection of the wall face occurred at the top of the wall and was 7 cm, or 4.7%
of the wall height. Due to the difficulty in achieving higher density, the TDA had a small settlement (approximately 2 cm), or 1.3% of
the wall height. Limitations of this research were presented at the end of the paper.
RÉSUMÉ : Cet article présente un test préliminaire sur table vibrante d’un mur de terre stabilisée mécaniquement et à échelle réduite
(MSE) et fait d’un remblai à base d’agrégats de pneus (TDA). Le mur modèle (MSE) a été construit à l'intérieur d'une boîte dont la
charpente est faite d’acier et qui a été placée sur une table vibrante unidimensionnelle. Le mur avait 1,5 m de haut, 1,2 m de
profondeur et 1,5 m de long et il était fait de cinq couches de remblai TDA qui étaient renforcées à l'aide d'une géogrille. Les
excitations du tremblement de terre de Loma Prieta de 1989 ont été intensifiées à partir d’une loi de similitude et elles ont été simulées
sur la table vibrante avec une accélération au sol dont la cible maximale était de 1,62 g. Quatre types de réponses sismiques ont été
mesurés: les accélérations de chaque couche du remblai renforcé, les déplacements latéraux de la paroi frontale au bas, au milieu et en
haut de la paroi, les fondements verticaux dynamiques de la paroi, et les contraintes verticales dynamiques à l’intérieur du remblai.
Ces réponses sismiques ont été présentées et analysées. En général, le mur MSE s’est bien comporté sans aucun dommage apparent.
La déviation horizontale maximale de la paroi frontale s'est produite dans la partie supérieure de la paroi et elle était de 7 cm, soit de
4,7% de la hauteur du mur. En raison de la difficulté à obtenir une densité plus élevée, le TDA a subi un léger tassement (d’environ 2
cm) soit de 1,3% de la hauteur du mur. Les limitations de cette recherche sont présentées à la fin du document.
KEYWORDS: Tire derived aggregates, TDA, MSE wall, seismic, shake table test.
1 INTRODUCTION
In each year, there were approximately 280 million waste tires
were discarded by American motorists, 40% of which were
disposed in landfills, stockpiles, or illegal dumps (FHWA
1997). These stockpiles of tires pose a potential threat to public
health, safety, and the environment. Tire shreds, also known as
tire derived aggregates (TDA), are pieces of processed and
shredded waste tires that can be used as lightweight and quick
fills for embankments, subgrades, bridge abutments, and
retaining wall backfills. TDA of different sizes have been
widely studied as alternative backfills in the past twenty years
and vast literature references are available (e.g., Humphrey and
Manion 1992; Humphrey 1998; Bosscher et al. 1992; Tweedie
et al. 1998; Strenk et al. 2007; Tandon et al. 2007). These
references provided understanding of the mechanical
characteristics and in-situ performance of embankments or
retaining walls using tire shreds or chips.
In contrast to the relatively rich literature on the static
behaviors of tire shreds, scarce experimental data are available
on the seismic performances of mechanically stabilized walls
and bridge abutments with tire shreds/chips as backfills. Tsang
(2008) was one of few researchers who studied a rubber-soil
mixture backfill under seismic conditions. In his shake table
tests, it was found that site response of the backfill was
nonlinear and helped absorb incident seismic waves.
Furthermore, Tsang (2008) raised the concern for the resonance
effects of the new backfill, which should be experimentally
tested. The recent shake table tests by Hazarika et al. (2008) on
gravity type model caisson protected by a cushioning tire chips
found that the tire chips substantially reduced the seismic load
against the caisson wall. Helwany et al. (2012) conducted a
full-scale shake table test on geotextile-reinforced-soil bridge
abutment, using a staged sinusoidal horizontal motion with
increasing amplitude up to 1.0 g. The abutment was 3.2 m tall
and concrete masonry unit (CMU) blocks were used as the
facing. Thorough data analyses of the tests indicated that the
model abutment safely withstood the bridge loads while being
subject to ground accelerations up to 1.0 g at 3 Hz.
This paper reports a preliminary shake table testing on the
seismic responses of a reduced-scale mechanically stabilized
‘earth’ (MSE) wall using TDA as backfill. Scaled historical
earthquake excitations were generated by the one-dimensional
shake table. The accelerations of the wall at different
elevations, the lateral displacements of the wall face, the
vertical settlements and vertical stresses during the simulated
40 seconds of shaking were recorded and analyzed.
2 MATERIALS AND METHODOLOGY
2.1 Material
There are two types of TDA that are used in the USA: type A
with a maximum size of 7.5 cm and type B with a maximum
size of 30.0 cm. In this research, the TDA was provided by a
TDA vendor in California, USA. The size distribution is shown
in Figure 1. It can be seen that the material’s maximum size is
approximately 10 cm, and 76% (by mass) TDA are smaller
than 7.5 cm. The TDA was judged to be close to type A.
