w
2w
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2 &
E 2 Geotextiles and geogrids in internally reinforced
soil walls allow reinforcement of the soil mass, creating a stable fill area behind the wall face.
Such a structure shown in Fig. 21.6 is an alternative to conventional gravity or cantilever
retaining walls used in many civil engineering structures. These have been found to be quite
economical in forest and hilly area.
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2g
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# Three-dimensional erosion control mats are used to
establish a reinforced truf in ditches, channels and slopes. The mats entangles with the root and
stem network of vegetation to greatly enhance its resistance to flow velocity. Top soil cover
may be used to enhance temporary erosion protection and early vegetative growth.
i
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2
2 E 2@e#
A To prevent the erosion of soil through the armouring
layer of rip-rip, Geotextiles are used as an interface The geotextile is in lieu of a conventional
graded aggregate filter. In this application, large armour stone or rip-nip, or in some cases
flexible concrete mattresses, are placed to protect the soil against erosion and wave attack. The
use of a geotextile in such situation has been shown to provide substantial savings over
conventional aggregate filter systems with far greater control during construction, particularly
in underwater applications.
i
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# 2w A cost effective alternative to stone rip-rap could be
a concrete forming system. The mats are typically constructed of water permeable, double-
layer woven fabric. The fabrics are positioned on the area to be protected, where they are filled
with a pumped structural grout.
&2h Geotextiles are used in subsurface drainage systems as a permeable
separator to keep soil out of the drainage media, but permit water to pass freely. Such systems
are needed under highways, parking lots, shorelines, walls, athletic fields, golf courses, race
tracks, lawns and other areas, typically shown in Fig. 21.7.