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PROJECT TITLE: INVESTIGATION OF CAUSES OF
FAILURE OF GRAVEL ROAD
CASE STUDY : LUMO ALI MBOA
PROJECT TYPE: PROBLEM SOLVING
NAME OF STUDENT:CAROL ANDREW PANTALEO
ADMISSION :100101P7312
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INTRODUCTIONLumo Ali mboa road, is located at Temeke
Municipality in Dar es salaam. It has the length of
1.2km. The road is made of natural gravel laid on asub grade. The road is unpaved and due to rapid
development of that area, the road has become
very useful for the transportation.
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PROBLEM STATEMENTThe road is characterized by existence of ruts,
corrugations, pot holes, skidding and depressionswhich lead to unsafe to road users, delays to
passengers and their goods, lack of freedom to
drivers maneuverability and uncomfortability to
passengers.
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OBJECTIVE
MAIN OBJECTIVE
To investigate the causes of failure of gravel road.
SPECIFIC OBJECTIVE
To determine the traffic volume.
To determine the drainage system.To conduct material testing for strength.
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OUTCOME OF THE PROJECTAt the end of this project ,causes of failure along the
road will be identified
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METHODOLOGYLiterature Review
Data CollectionData Analysis
Recommendation
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LITERATURE REVIEW
Agravel road
Is a type of unpaved road surfaced with gravel that hasbeen brought to the site from a quarry or stream bed.
They are common in less-developed nations, and also
in the rural areas of developed nations such as
Canada and the United States. In New Zealand, theyare known as 'metal roads'. They may be referred to
as 'dirt roads' in common speech, but that term is used
more for unimproved roads with no surface material
added. If well constructed and maintained, a gravelroad is an all-weather road.
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CHARATERISTICS OF GRAVEL ROADA good gravel road surface, a proper worn and
adequate drainage. Its good condition ismaintained by periodically, smoothing and
reshaping its surface and shoulders. This bulletin
describes the characteristics of the gravel road and
how to maintain one.
Also good gravel needs gravel sands and silt in
the proper proportions to support traffic load, resist
abrasion, shed water and enhance the soil abilityto absorb and disperse water.
A good gravel should have ditches should have a
v shape and should be moved and cleared of
sediments and debris to prevent washout.
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TYPES OF GRAVEL ROAD SECTIONS
FEATHER EDGE TYPE
Is constructed over the sub grade with varying thickness,
so as to obtain the desired cross slope for the pavement
surface.
TRENCH TYPE
The sub grade is prepared by excavating a shallow
trench where this method of construction is the most
preferred for construction of gravel road.
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TYPES OF DEFECTS ON GRAVEL ROAD
POTHOLES
is a type of disruption in the surface of a
roadway where a portion of the road material
has broken away, leaving a hole.Causes
Potholes almost always result from road
sections on poorly drained soils
Water penetrate on the road surfaceERROSION GULLIES
They are in the form of channels, It may
increase in size and destroy the road
section once it has formed.
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DEPRESSIONThese are small hollows occurs in the pavement.
Usually they develop from local defects such as low
compaction or insufficient pavement strength . They
increase the roughness of the pavement
SOFT SPORTS
These are weak points which can be found on the surface ofunpaved road.
CAUSES
Insufficient camber (water does not drain off quickly)
Poor or lack camber which does not
shade off rain water quickly.
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GENARAL CAUSES OF FAILURE OF
GRAVEL ROAD
The following are the causes of failure of a gravel road;Increase in traffic volume
Environmental factors
Unsuitable materials of construction
Poor drainage system
Poor construction practice
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Increase in traffic volume
Traffic volume is the counting process whichinvolving number of traffic (car, bus truck,trailers) passing through out the road onwhich a movement is per unit time at aspecified time, a selected time period inhours, days, week month or year.
Purpose of traffic volume study
It is important in traffic design, research and
planning. Information obtained is used in the research
of gravel rod deteriorations.
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Environmental factors
This involve rainfall and water disposal fromchambers and people residential houses where by
water cause wearing off (wash out of looses) materialon surface of gravel road.
Also too much moisture will cause the crust to breakup and reducing capacity and leading to rapid surfacedeterioration.
Unsuitable material for constructionSome material are not proper for construction
purporse of gravel road also lead to poor blending
process because for good all weather surface, gravelroad must be properly blended where for poorblending will make stones and fines not compactedtogether and forming weak, undurable surface crust tocarry the traffic load and shed water.
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Poor drainage system
Proper side ditches and cross surface drainage are
also important, without proper drainage, road surfaces
become rutted, surface material wash away and road
can become flooded and impassable.
Ditches collect run off from shoulders and carry it to
streams and other natural drainage locations. The right ofthe way usually limits ditch sizes, the most common and
economical to build ditch shape is a V.
Also ditches are clogged with sediments which lead to
overflowing and possible washout.
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Poor construction practice
This involve shoulders should also be constructed of
aggregate, the shoulder must slope as much or more
than the crown for good drainage and to prevent waterfrom flowing back toward the road surface.
A strong and durable side drains for gravel road
should be constructed with stones ( stone armoreddrains ) with cement.
Poor compaction of crown and surface material also
affects cross surface drainage, If the crown will
designed properly, then water will run off and into theshoulders and poor compaction surface material has
many voids to absorb water and let most of it run off.
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DATA COLLECTION
I. FIELD MEASURING
Field measuring of defect occurring and types. Collection of sample at the site
Provide photographs
II. SOIL LABORATORY TEST Sieve analysis (Grading) Test,
Atterberg Limit test,
Compaction Test, California bearing ratio ( CBR) Test.
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III. FIELD TESTING Field density for compaction with Maximum Dry
density (MDD)
Field water content for compaction with Optimum
Moisture Content(OMC).
DATA COLLECTION
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DATA COLLECTION
SAMPLING OF THE GRAVEL MATERIAL
The test sample were obtained from Lumo- Ali mboa road which islocated at Temeke municipal. One sample was collected in order todetermine the engineering properties of the soil along this strength.Representative sample were taken at a 1.3m depth
PREPARATION OF THE SAMPLE FOR TEST
It is necessary that the soil sample material for laboratory test is free fromexcess moisture beyond its natural moisture content, due to this effect thesoil was air dried by spreading over dry polythene sheets. This is importantfor sensitive sieving methods such as those required in the determination ofparticle size distribution, as the moist soil will be difficult to pass over theseparating micro sieves
PROGRESSING OF THE TEST
In order to determine the engineering properties of the soil sample, thefollowing test have been carried out starting from ch:
0+250,0+500,0+750,1+000.
.
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DATA ANALYSIS
The test performed for analyzing the data were
Compaction Test
California Bearing Ratio Test
Atterberg Limit Test
Sieve analysis
And the results through the tests conductedwere obtained
S f th i F l i l i i bt i i D t f l i
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Some of the main Formula involving in obtaining Data for analysis are:
Bulk Density = mass/volume
Dry Density = bulk density1+moisture content
Compaction = Dry density
MDD
Plastic Index = Liquid Limit
Plastic Limit
Moisture content = 100x mass of water/mass of dry soil
Linear Shrinkage = Initial Length(LO) Final Length(Lf)
Initial Length (LO)
The results obtained shows the various relationship between
engineering properties of soil materials as follows:-
Th l b i d h h i
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The results obtained shows the various
relationship between engineering properties of soil
materials as follows:-
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SAND
Chainage OMC MDD
0+250 11.88% 1.948kg/m3
0+750 9.60% 1.950kg/m3
GRAVEL
0+750 8.97% 2.013kg/m3
SUMMARY OF RESULTS FOR SOIL TEST
Table 1:compaction test results
Table 2: California Bearing Ratio Test resultsT bl 3 Si l i l
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SAND
chainage 56 blows
5 layers
4.5 kg rammer
30 blows
5 layers
4.5 kg rammer
56 blows
3 layers
2.5 kg rammer
0+250 17 16 17
0+750 20 19 18
GRAVEL
0+750 48 46 43
Table 2: California Bearing Ratio Test results
CBR Values
CLASSIFICATION
SAND (0+250) SAND(0+750) GRAVEL(0+750)
USCS
%Gravels 11 7 51
%Sand 80 69 44
%Fines 9 23 5
LL(%) 20 31 20
PL(%) NP NP 10
PI(%) NP NP 10
Table 3: Sieve analysis results
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From the graph above,
it shows that there is a decrease of Optimum moisture content from chainage 0+250 to
chainage 0+750 but there is an increase of maximum dry density from chainage 0+250
to chainage 0+750.
VARIATION OF OMC AND MDD AT DIFFERENT
CHAINAGE FOR A SUB GRADE
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VARIATION OF CBR VALUE AT DIFFERENT
CHAINAGE FOR A SUB GRADE
From the graph above,
it shows that there is a increase of CBR value from chainage 0+250 to chainage 0+750.
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RELATIONSHIP BETWEEN %MDD(COMPACTION) AND CBR VALUE
AT CHAINAGE 0+250 FOR SUB GRADE.
1.0
10.0
100.0
90.0 92.0 94.0 96.0 98.0 100.0 102.0 104.0 106.0 108.0 110.0
CBR4daysSoaked(%)
% MDD
Plot of CBR, 4 days soaked (log scale) versus% of Maximum Dry Density
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RELATIONSHIP BETWEEN %MDD(COMPACTION) AND CBR VALUE
AT CHAINAGE (0+750) FOR SUB GRADE.
1.0
10.0
100.0
90.0 92.0 94.0 96.0 98.0 100.0 102.0 104.0 106.0 108.0 110.0
CBR4daysSoaked(%)
% MDD
Plot of CBR, 4 days soaked (log scale) versus% of Maximum Dry Density
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RELATIONSHIP BETWEEN %MDD(COMPACTION) AND CBR
VALUE AT CHAINAGE (0+750) FOR GRAVEL.
1.0
10.0
100.0
85.0 87.0 89.0 91.0 93.0 95.0 97.0 99.0 101.0
CBR4daysSoaked(%)
% MDD
Plot of CBR, 4 days soaked (log scale) versus% of Maximum Dry Density
REFERENCE
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REFERENCEBrian Kent, K. a. (2010). Gravel Road Maintenance
Manual. Norway: Taylor and Francinc Group,LLC,Clyde
Walton, David Rocqure.CML,NOTEBY,SINTEF,VIANOVA. (2000). Laboratory
Testing Manual. Skjetten Norway: Novum Grafisk AS.
Justo, S. a. (1990). Highway Engineering. London New
York: Taylor and Francis Group,LLC.
Smith, G. S. (1995). Element of Soil Mechanics.
.