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Geosynthetic Reinforced Soil Wall Performance under Heavy Rainfall
La performance du mur en sol renforcé par géosynthétiques sous de fortes pluies
Yoo C., Jang D.W.
Dept. of Civil and Environmental Engineering, Sungkyunkwan University, Suwon, Korea
ABSTRACT: Global warming is now considered to be one of the greatest threats to earth. The direct consequence of the temperature
increase due to the global warming include a rise in sea levels and a change in the amount and pattern of precipitation. Since the
amount pattern of precipitation have of paramount implications to short and long-term performance of geo-structures, geo-engineers
should pay attention to the issue of global warming. In this paper, the results of laboratory investigation into the effect of rainfall on
the performance of geosynthetic reinforced soil wall (GRSW) are presented. A series of model tests were performed using reduced
scale model walls, which were reduced from a full-scale GRS wall according to the similitude law. The model GRSWs were
subjected to cycles of wetting and drying process with different rainfall intensties but with a same amount. The results show that the
cycles of wetting and drying associated with a heavy rainfall may induce additional wall displacement and reinforcement strains in
GRSWs, and that such trends have significant implications to GRSW stability, especially for walls designed with marginal factor of
safety in terms of long-term performance.
RÉSUMÉ : Le réchauffement climatique est aujourd'hui considéré comme l'une des plus grandes menaces pour la terre. Les
conséquences directes de l'augmentation de température due au réchauffement climatique incluent notamment l’élévation du niveau
des mers et un changement dans la quantité et le régime des précipitations. Ces paramètres ayant des implications primordiales sur les
performances à court et à long terme de géo-structures, les géo-ingénieurs devraient prêter attention à la question du réchauffement
climatique. Dans cet article, les résultats des études en laboratoire sur les effets de fortes précipitations pour la performance des murs
en sol renforcé par géosynthétiques (GRSW) sont présentés. Une série d'essais sur modèles réduits a été réalisée avec des modèles
réduits d'un mur à pleine échelle GRS suivant la loi de similitude. Les modèles GRSW ont été soumis à des cycles de mouillage et de
séchage avec des intensités pluviométriques différentes. Les résultats montrent que les cycles de mouillage et de séchage associés à
une forte pluie peuvent provoquer un déplacement supplémentaire du mur et les tensions dans le renforcement, et que ces tendances
ont des implications importantes pour les GRSW conçus avec un faible facteur de sécurité en termes de performance à long terme
KEYWORDS: Climate change, Rainfall, Reduced-scale model test, Matric suction, Pore water pressure
1 INTRODUCTION
Since the early 20
th
century, Earth’s mean surface temperature
has increased by about
with about two-thirds of the
increase occurring since 1980. A climate model projects that
the global surface temperature will probably rise further
to
during the twenty-first century (IPCC 2007). An increase
in global temperature will cause sea levels to rise and will
change amount and pattern of precipitation as well. Korea is no
exception from the issue of global warming. The Korean
Meteorological Administration (KMA) has made a report on
climate change characteristics during the period of 1996~2005
that the mean temperature has increased by
from the last
30 year mean temperature during the period between 1971 to
2000 (KMA 2008). The annual precipitation has also increased
by 11%. It is projected that the temperature increase will be as
great as
with an annual precipitation increase of 17% by
the end of 21
st
century. Since the increase in precipitation has of
paramount implications to short and long-term performance of
geo-structures, geo-engineers should pay attention to the issue
of global warming.
C
o
8.0
1.1
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4.6
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6.0
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In response to the need for addressing the effect of rainfall
on geo-structures for design and construction, a number of
studies have been undertaken. Most of the available studies are,
however, focused more or less on the effect of rainfall on
natural slopes (Gasmo et al. 2000, Tsaparas et al. 2002, Zhan
and Ng 2004, Cai and Ugai 2004, Cheuk et a l. 2005, Garcia et
al. 2006, Rahardio et al. 2007, Rahimi et al. 2011) except Blake
et al. (2003) and Yoo et al. (2008a, 2008b) in which the effect
of rainfall on retaining structures was investigated. More
specifically, Yoo et al. (2008a, 2008b) investigated the effect of
rainfall on GRSWs using a series of limit equilibrium analyses
within the framework of unsaturated shear strength, coupled
with transient infiltration analyses. Much still need to be
studied on the subject of the effect of rainfall on geo-structures.
In this paper, the results of a laboratory investigation into the
effect of rainfall on the performance of geosynthetic reinforced
soil wall (GRSW) are presented. A series of model tests were
performed using reduced scale model walls, which were
reduced from a full-scale GRS wall according to the similitude
law. The model GRSWs were subjected to cycles of wetting and
drying process with different rainfall intensties but with the
same total rainfall.
2 REDUCED SCALE MODEL TEST
A series of reduced scale model tests were performed with due
consideration of the wetting and drying process. Details of the
model tests and the results are given in the subsequent sections.
2.1 Model wall and backfill soil
The reduced scale model tests were performed using 0.5 m high
reduced scale model GRSWs constructed in a test box, having
dimensions of 0.9 m x 0.4 m in plan and 0.6 m in height, made
of 2 cm thick Plexiglas as shown in Figure 1. The test box was
made sufficiently rigid to maintain the plane-strain condition
during test. The wall facing, made of 0.5 cm thick Plexiglas,
