821
Measured and Simulated Interactions between Kenaf Geogrid Limited Life
Geosynthetics (LLGs) and Silty Sand Backfill
Interactions mesurées et simulées entre kénaf géogrille limitée Géosynthétiques vie
(LLGs) et de remblai de sable limoneux
Tanchaisawat T.
Department of Civil Engineering, Faculty of Engineering, Chiang Mai University, THAILAND
Bergado D.T., Artidteang S.
School of Engineering and Technology, Asian Institute of Technology, THAILAND
ABSTRACT: New types of natural fiber reinforcing materials have been introduced recently in geotechnical applications; for
example, jute, coir, sugarcane bagasse. Natural fibers can be modified into woven geogrid and used in geotechnical engineering
applications and generally classified as Limited Life Geosynthetics (LLGs). The natural fiber used for this study was roselle or Thai
Kenaf which was made into geogrid with opening size of 4 mm was investigated. Locally available silty sand was used for compacted
backfill material. Large scale pullout and direct shear tests were performed in order to investigate interaction mechanism of kenaf
geogrid and compacted sand. Numerical simulation was studied in terms of its reinforcement mechanism on plane strain mode. From
the results of sensitivity analyses, the interaction coefficient and axial stiffness of the geogrid were found to be important parameters
affecting the efficiency of geogrid. The interaction coefficient R
inter
is 0.9 for pullout mechanism and 0.6 for direct shear mechanism.
The recommended parameters for these reinforced systems have been introduced to use as sustainable geosynthetics. Furthermore,
Kenaf geogrid which is LLGs concept can be widely promoted for natural fiber application in many countries.
RÉSUMÉ: De nouveaux types de matériaux en fibres naturelles de renfort ont été introduits récemment dans les applications
géotechniques, par exemple, le jute, le coco, la bagasse de canne à sucre. Les fibres naturelles peuvent être modifiés en tissé géogrille
et utilisé dans les applications d'ingénierie géotechnique et généralement classés comme Géosynthétiques durée de vie limitée (LLGs).
La fibre naturelle utilisée pour cette étude était kénaf oseille ou thaïlandais qui a été faite en géogrille avec l'ouverture de la taille de 4
mm a été étudiée. Sable limoneux disponible localement a été utilisé comme matériau de remblai compacté. Retrait à grande échelle
et essais de cisaillement direct ont été réalisées afin d'étudier mécanisme d'interaction de kenaf géogrille et de sable compacté. La
simulation numérique a été étudiée en fonction de son mécanisme de renforcement du mode de déformation plane. D'après les
résultats des analyses de sensibilité, le coefficient d'interaction et de la rigidité axiale de la géogrille se sont révélés être des
paramètres importants qui influent sur l'efficacité de la géogrille. Le Rinter coefficient d'interaction est de 0,9 pour mécanisme de
retrait et de 0,6 pour le mécanisme de cisaillement direct. Les paramètres recommandés pour ces systèmes renforcés ont été mis en
place pour l'utiliser comme géosynthétiques durables. En outre, le kénaf géogrille qui est le concept LLGs peut être largement promu
pour la demande de fibres naturelles dans de nombreux pays.
KEYWORDS: interaction, geogrid, kenaf, simulation.
1 SUSTAINABLE GEOSYNTHETICS
Living sustainably, according to many, requires that we use
resources to meet our present needs without compromising the
ability of future generations to meet their needs. Living
sustainably does not, however, require that we live in thatch
huts that periodically biodegrade. According to the free online
encyclopedia, the definition of sustainability is simply “the
capacity to endure”. People, resources, and the environment are
all intertwined. We have an impact on the environment when
we extract raw materials, manufacture, install, use and dispose
of our products. This is why endurance counts. A longer lasting
geosynthetic product delays the repeat of the manufacturing
cycle, uses fewer resources, costs less money and causes less
stress on the environment.
Belton (2008) hit the sustainable issue head-on by
illustrating how geotextiles and geogrids save large quantities of
natural materials, mainly stone aggregate for highways,
railroads, parking lots, and building foundations. They also
described the use of on-site soils for use in walls and slopes
rather than using imported sands and gravels. In addition they
bring into context the carbon footprint of both materials and the
processes involved in obtaining these materials, e.g.,
transportation from quarries to construction sites. Interestingly,
the intent of this tax was to increase the use of recycled
materials but it appears to more immediately play into the use of
geosynthetics, to all of our advantage. Robinson and Quirk
(2008) give several tables of aggregate thickness saved using
geogrids in highway base courses. They also illustrate aggregate
savings when using geodrains, fin drains, and geocomposites in
walls and bridge abutments. Lastly, they described the many
uses of these drainage geosynthetics in waste containment.
Landfills require drainage of leachate at their base, drainage of
water at the surface, and sometimes drainage within the waste
mass itself.
2 NATURAL FIBERS REINFORCEMENT FOR GREEN
TECHNOLOGY
Environment protection is important because construction
represents a major contribution to climate change, resource
depletion and pollution at a global level. This strategy for more
sustainable construction is a significant step towards a more
successful, socially and environmental friendly atmosphere
making a strong contribution to the better quality of life
signaled by our sustainable development strategy (Mwasha,
2009).
The biobased geotextiles research project has been
conducted by several Institutions in United Kingdom by Sarsby
et., al. (2006), Mwasha (2005), Mwasha and Sarsby (2003).
Today most biodegradable geotextiles are used in erosion
control where they serve to stabilize the soil surface while
natural vegetation is established. There are other numerous
