Matakuliah
Tahun
Versi
: S0182/Studi Kasus Dalam Teknik Sipil
: Juli 2005
: 01/01
Pertemuan 06
<<Judul>>
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Learning Outcomes
Mahasiswa dapat membandingkan kasuskasus yang terjadi dengan berbagai
alternatif yang dipilih  C4
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Outline Materi
• Analisa pemecahan masalah
• Beberapa alternatif pemecahan masalah
• Kasus kegagalan konstruksi yang mungkin
terjadi
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PAVEMENT STRUCTURAL
FAILURE
This is when the PAVEMENT has failed, maybe not completely, but in a major
way.
The PAVEMENT is no longer able to absorb and transmit the wheel loading
through the fabric of the road without causing fairly rapid further deterioration
of the road pavement.
The layers making up the PAVEMENT have failed for various reasons, E.g.
through age, inadequate design, or an altering in requirements of the strength
of the PAVEMENT by increased traffic flow/weight, impeded drainage
decreasing subgrade strength, etc..
When you have STRUCTURAL FAILURE the solution is always a form of
RECONSTRUCTION.
I say a form of RECONSTRUCTION because it is not always necessary or even
advisable to remove material that is still sound and will provide a good base to
new work.
If total RECONSTRUCTION is needed so be it, but you really need the experts in
here to advise,
I mean real experts with a few years of real experience not just somebody with
a fancy machine, however much data they can provide.
SEEK GOOD ADVICE !
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DRAINAGE
• DRAINAGE is VERY! VERY! VERY! IMPORTANT, both in relation to
road pavement construction and maintenance.
You MUST keep the water-table low to prevent the moisture content
of the subgrade increasing, and hence decreasing the subgrade
strength, measured by the CBR value, on which the road pavement
was designed.
If this is not done by the use of french drains, or even open ditches
adjacent to the highway, the road pavement will weaken and fail.
The water-table of naturally occurring ground will rise and fall from
winter to summer, bear this in mind when designing the road, and
design for the highest water table (weakest subgrade) conditions.
Good drainage will help to keep the water table of the road
pavement in equilibrium.
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DRAINAGE
Also the road pavement itself must be constructed so that it will
drain in the event of a failure of the integrity of the surfacing layers,
i.e. if water is able to enter the road pavement there must be a path
for it to exit.
The internal drainage function of a road pavement is usually
performed by the GSB layer, this itself MUST be drained in some
way.
In my younger days this function was provided by a french drain on
the lower side channel and periodically piped to an outside drain or
open ditch, but this practice seems to have become redundant.
Water below the road pavement must be kept low and not be
allowed to rise up into the construction layers, (and water CAN flow
upwards, by capillary action).
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DRAINAGE
• IF WATER IS ABLE TO ENTER THE ROAD
PAVEMENT, FOR WHAT EVER REASON, THE
DESIGN OF THE ROAD PAVEMENT SHOULD
BE SUCH THAT THE WATER HAS A WAY
OUT, THIS IS USUALLY THROUGH A SUBBASE LAYER THAT IS DRAINED TO AN
INSTALLED DRAINAGE SYSTEM.
IF WATER CANNOT FIND A PATH OUT OUT
THE ROAD PAVEMENT FAILURE OF THE
HIGHWAY WILL BE PREMATURE AND SWIFT.
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FAILURE
• AREAS OF FAILURE
When you have areas of failure in a road surface it is
necessary to investigate the cause of the failure to
decide the course of action to effect a permanent
repair.
• Excavating a trial hole is an excellent way of finding
out just what the road pavement consists of, or does
not consist of, as the case may be.
• It will also indicate the nature of the failure, i.e.
failure of the materials making up the road
pavement, lack of construction thickness, high water
table/poor drainage, etc..
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• THE BASICS
It is good practice to record all the trial hole
details.
• Record the thickness of the various pavment
layers, i.e. wearing course, basecourse,
roadbase, sub-base.
• If you are sufficiently knowledgeable identify
the various materials, e.g. hot rolled asphalt
wearing course with precoats, or close
graded macadam wearing course, etc..
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• If possible be on site when the trial hole is excavated
and observe the procedure, it is amazing what you
can learn just from using your eyes.
• How hard was it for the workman to jack hammer
through the various layers.
If it was easy the materials in the varying pavement
layers are not that strong.
If it was "hard going" through the various layers the
pavement is strong, and the materials are unlikely to
be the cause of any failure.
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• Even something as simple as the degree of difficulty in
digging the hole will give an indication of the strength of
the materials that make up its construction.
There is very little substitute for experience in trial hole
assessment but some things are common sense:1) How thick is the construction, how thick are the
various layers.
2 ) What type of material is it? bituminous, concrete,
granular, what condition is it in.
3) What is the height of the water table.
4) What is the type of subgrade, what is the CBR of the
subgrade.
5) Is the road pavement material excavated in sound
condition or stripping and loose.
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<< CLOSING>>
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