2. Keller Group : It is the largest independent
geotechnical solutions specialist in the world. With
operations in more than 40 countries across six
continents.
Established in 1860 and has more than 20 major
acquisitions since 2018.
Headquarters: London, England.
In India: Chennai
Keller work at Polavaram project:
Jet grouting for up stream and downstream
Coffer dam.
Working time :4months
Jet grouting
3.
4.
5. SILENT FEATURES
LOCATION: Up stream and down
steam of ECRF dam.
DESIGN FLOOD: 28 lakh cusecs.
U/S SIDE AND D/S SIDE COFFER
DAM LENGTH:2356m and 1613m
TOP BANK LEVEL OF U/S SIDE
AND D/S SIDE COFFER DAM :
42.03m AND 28.00m
TYPE OF CUT OFF: Jet grouting
20m at u/s side and 10m at d/s
side.
7. Geotechnical aspects:
Sand is cohesion less soil so it as
low water tightness compared to
cohesion soils.
To with stand the pressure of
400pas and also to acts as a barrier
to stop the water from u/s side of
dam to d/s side “Jet grouting” is
selected.
Generally co efficient of
permeability of sands are 10^-6,so
we have increase it up to 10^-9.
Bed rock is found at 40m to 90m
from the river bed.
Depth of sand layers is varies from
26m to 40 m.
Slit and clay: varies at different
depths.
Pressure at bottom of the dam is
400pas.
42m
Up stream coffer dam section:
sand
silt
clay
Bed rock
10. CONSTRUCTION SEQUENCE:
Grout
Back flow
Grout jet
Grout
Air Backflo
w
Air
shrouded
grout jet
Water
Air Backflo
w
Air
shroudedwater jet
Grout
Grout jet
1.DRILL THE HOLE 2.ROTATE THE STRING WITH KINETIC ENERGY 3.COMPLETE THE
WITH THE DRILL STRING LIFT UP AND START GROUTING GROUT
DRILL STRING
NOSSIL
1-PHASE SYSTEM 2-PHASE SYSTEM 3-PHASE SYSTEM
11. Working details
1.Outter and inner diameter of drilling rod are 114.4mm
and 35mm respectively.
2.Daimeter of the Nozzle is 4.5mm.
3.Roatation of the string 6rpm.
4.Withdraw of the grout 25cm/min.
5.Daimeter of the column is 2m and center to center
spacing is 1.5m and pitch distance of 40mm.
6.No of grout columns are1530.
7.Over lapping of columns are 0.5m.
8.Depth of column is 2m.
9. Grout Pressure 400pas and air pressure 1-6bar.
13. Conclusion
The Polavaram Project is the Biggest ongoing project in India.
The Irrigation projects are very much necessary for the development of any
state.
Polavaram project has the decades of history and finally now the project was
on full track and work is going on 24 X 7 .
It is the first of its kind in India and it has many specialties.
The government is trying its level best to complete the project as fast as
possible.
As it is a Multi purpose project it has many benefits and is the LIFE LINE
OF ANDHRA PRADESH.
