Ground improvement is making positive changes to the natural
properties of a soil by means treatment or addition of other materials. The
main purpose of ground improvement work is to increase the capability of the
soil to retain the load exerted on it by the any structure. There are a few
ground improvement methods including deep compaction, vibration columns,
vibro-replacement and geotextile sand piles.
Soil compaction is a mechanical
process of increasing the density of the soil by applying stress onto the
ground. The process of soil compaction will reduce the void ratio of the soil,
thus make it more compacted. More compacted soil will have higher strength
compared to the less compacted soil.
Embankment is a thick wall of earth usually used to hold water or
to uprise the base of any construction projects such as roads and railways.
Embankment consist of a few compacted layers until it reaches the required
height and strength. Embankment are constructed mostly with soil, but also
including any other possible materials that meet the allowable specification
and quality requirement such as aggregates and rocks.
There are a few steps need to be done during the construction work
of embankment. First of all, the embankment site should be cleared so that any
unwanted materials will not affect the layer of embankment. If embankment is
built on an existing road, the existing
road must first removed. After all the unwanted materials and debris are
cleared from the embankment site, the embankment material are placed. The
embankment materials need to be compacted to a certain specifications.
There are some equipment that can be used to do the compaction in
the work field such as vibratory rollers, sheepsfoot rollers and smooth wheel
rollers. But not all equipment can be used for all soil type. For example,
vibratory rollers are generally used in more silty soils while sheepsfoot are
used for clayey and plastic soils.
After all the compaction works are done, the soil needs to be
evaluated whether it already achieves the requirement or not. Some tests are
conducted to know the characteristic of newly compacted soil. Density and water
content are usually the most common aspects that are evaluated on the soil at
the work field. Both specifications cab be tested by conducting laboratory
test. Embankment will achieve higher strength at maximum density and maximum
density can be obtained when the soil has achieved optimum water content. One
the embankment is finished, a process called proof rolling need to be done to
indicate the uniformity of the supporting ability of the embankment.