Geosynthetics in
Construction of Roads
on Soft Subgrades
The purpose of this article is to briefly describe
the potential applications of geosynthetics and
highlight their advantages.
Introduction
Construction of roads on soft saturated
compressible soils is a difficult
and challenging task. Very often conventional
techniques do not result in
a satisfactory solution and have several
limitations - poor performance,
short service life and high maintenance
costs etc.
Geosynthetics (a collective name
for a family of products which includes
geogrids, geotextiles, geonets,
geocomposites etc.) are extensively
used by highway engineers all over
the world, to devise proven cost effective
solutions for the construction
of roads on problematic subgrades.
The purpose of this article is to briefly
describe the potential applications of
geosynthetics and highlight their advantages.
Problems of Roads on Soft
Subgrades
Design and construction of roads on
soft, saturated and compressible subgrades present several problems:
* Due to very low bearing capacity
considerably thick subbase/base
courses have to be provided.
* Under repeated loads granular
subbase and base layers deteriorate
due to aggregate penetration
into the subgrade and pumping of
fines from the subgrade. Hence, a
high sacrificial thickness has to be
provided, or alternatively the design
life will be short.
* Due to high compressibility of the
subgrade, differential settlements
could be high, resulting in cracks
etc.
* Movement of construction equipment
will be difficult.
* Loss of aggregate into the soft
subgrade during placing and compaction
of the subbase/base layers.
* It will be difficult to compact the
first few lifts of the subbase/base
...
....contd.
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