CE6504 - HIGHWAY ENGINEERING DESIGN AND CONSTRUCTION OF EMBANKMENT

2. INTRODUCTION
 When the sub grade line of highway
is raised the existing ground level, the
embankment is constructed.

3. NECESSITY OF Constructing THE PAVEMENT
 Make the subgrade level above the ground
water table
 Satisfy the vertical alignment of a
highway.

4. Design and construction stages
 Evaluate the embankment height
 Embankment materials
 Compaction and its materials
 Construct the embankment with equal
slopes
 Check settlement

5. Design of embankment
 The embankment design elements are
as follows…..
Selection of dimensions
Slopes
Settlement analysis
Materials
Drainage

6. Selection of dimensions
 The dimensions are select due to the
roadway width , height and its side
slopes.
Width - its fixed as per IS
recommendations . It may be single, two and
multiple lane roads.
Height - its based on desired grade line
of the highway and the topography
Side slope - in this basis generally flat slope is
considered , because of the erosion control

7. Stability of slopes
 Sloping surfaces are subjected to get
shearing stresses at all intervals
 If the shear stress more, then a surface is
formed at a failure.
 For the failure of slope the main reason is
shear stresses are non uniform at all
intervals
 If the failure problem arrives means
correct the slope shape to the normal
sloping points

8. Types of slopes
 Infinite slope: it’s the type of slope which
is give equal extent and uniform slope to
the normal surface conditions.
 Finite slope: in this type the slope
having limited height

9. Settlement and stability foundation
It occur due to compression of fill
material in the subgrade.
Compaction is the main program of
settlement
If the compaction is not even then the
settlement is collapse
F.o.s should be more than three means
there is no other problems due to
settlement, if problem arise convert equal
stresses depends upon F.O.S

10. Selection of embankment materials
 The embankment materials should
have the strength and stability.
 Silts and clays are not a constructing
soil,
 On the site locating soil is best to the
embankment foundation

11. The soil properties may contain
the following characteristics
 Soil have more strength and stability.
 High plastic soils should be avoided
during construction
 Soil should have good drainage
properties.
 Clay soils are not satisfy the drainage
conditions
 The high density compacted soils should
be prepared in the construction.

12. Drainage system
 Embankment height is highly notified on
8m.
 Such a locations some of damages may
occur the cause of rain water
 When rain water falls highly means
erosion will occur on the slopes and
shoulders.
 This erosion may be turn into road
pavement

13. Cont…
 Here this possible cause embankment
drainage is important one.
 Soil type, height of embankment, high
rainfall, are the reasons may appear
the erosion
 Let us we the following image how to
the embankment drainage working on
a highway

15. EMBANKMENT WEAK SOILS
 In the location weak soil attained
special designs are considered
 If the un suitable soil presents in the
subgrade means the soil remove that
place by the use of deep foundation
 The structure design conditions are
not satisfy, immediately the structure
redesigned by the use of light weight
materials.

16. Cont…
 Removing poor materials in
subgrade
 Replace good resisting materials
 Treating the soil such improve the
properties

17. construction
 The construction techniques may depends
upon the following cases..
 Borrow pit – excavate soil
 borrow pit may represent the IRC classification.
 It should locate the road boundary
 It should be in rectangular shape
 Every borrow pits having a distance of 5m
 The maximum depth is 1.5m… this depth is
limited depth of borrow pit

18. Cleaning of natural ground
• This process may undertaken the
earthwork for a embankment
construction
• Its consist of removing trees, roots,
obstacles etc..
• The top soil is retained and highly
compacted soil is placed on the
surface

19. Compaction due to original ground
 Dry density of soil may be have the
density of 90%.
 In the original ground (that means
loosening soil) watering and rolling is
provided in the layers of 25cm.
 This watering, rolling treatment has
extended to a depth of 0.5m.

20. Compaction of embankment
 Earlier embankment is constructed by
rolling
 Soil is dumped on the ground surface
 The water content should be in 2%
 Required water added on the site
 Soil spread along over the surface
with a depth of 25cm
 The mechanical equipment is needed
to compaction

21. Cont…
 Standard three wheel steel tyred
rollers are used to the compaction
 Compaction of each layer is called as
lift.
 This main method is called as
compaction