EMBANKMENT CONSTRUCTION

S.R.V Engineering CollegeSembodai 614809

CE6504 – HIGHWAY ENGINEERING

Department Of Civil Engineering

INTRODUCTION

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

NECESSITY OF Constructing THE PAVEMENT

Make the subgrade level above the ground water table

Satisfy the vertical alignment of a highway.

Design and construction stagesEvaluate the embankment heightEmbankment materialsCompaction and its materialsConstruct the embankment with equal

slopesCheck settlement

Design of embankmentThe embankment design

elements are as follows…..Selection of dimensionsSlopesSettlement analysisMaterialsDrainage

Selection of dimensionsThe 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

Stability of slopesSloping surfaces are subjected to get

shearing stresses at all intervalsIf 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

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

Settlement and stability foundation

It occur due to compression of fill material in the subgrade.

Compaction is the main program of settlementIf the compaction is not even then the

settlement is collapseF.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

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

The soil properties may contain the following characteristics Soil have more strength and stability.High plastic soils should be avoided

during constructionSoil should have good drainage

properties.Clay soils are not satisfy the drainage

conditionsThe high density compacted soils should

be prepared in the construction.

Drainage systemEmbankment height is highly notified on

8m.Such a locations some of damages may

occur the cause of rain waterWhen rain water falls highly means

erosion will occur on the slopes and shoulders.

This erosion may be turn into road pavement

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

EMBANKMENT WEAK SOILSIn the location weak soil attained

special designs are consideredIf 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.

Cont…Removing poor materials in subgrade

Replace good resisting materials

Treating the soil such improve the properties

constructionThe construction techniques may

depends upon the following cases..Borrow pit – excavate soilborrow pit may represent the IRC classification. It should locate the road boundary It should be in rectangular shapeEvery borrow pits having a distance of 5mThe maximum depth is 1.5m… this depth is

limited depth of borrow pit

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

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.

Compaction of embankmentEarlier embankment is constructed

by rollingSoil is dumped on the ground surfaceThe water content should be in 2%Required water added on the site Soil spread along over the surface

with a depth of 25cmThe mechanical equipment is

needed to compaction

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

The End