27-07-2016 1 GEOSYNTHETICS IN DAMS Dr. G. Venkatappa Rao Department of Civil Engineering, Indian Institute of Technology Gandhinagar Geosynthetics Modern civil engineering construction materials Modify/Improve soil/geologic material behaviour Developed/Synthesized for specific function or application in construction More than 1billion sq m annual use
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GEOSYNTHETICS IN DAMS€¦ · GEOSYNTHETICS IN DAMS Dr. G. Venkatappa Rao Department of Civil Engineering, Indian Institute of Technology Gandhinagar Geosynthetics Modern civil engineering
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GEOSYNTHETICS IN DAMS
Dr. G. Venkatappa Rao
Department of Civil Engineering,
Indian Institute of Technology Gandhinagar
Geosynthetics
Modern civil engineering construction
materials
Modify/Improve soil/geologic material
behaviour
Developed/Synthesized for specific
function or application in construction
More than 1billion sq m annual use
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Geosynthetics –The wide variety
Geotextiles –Woven, non-woven Filter
fabrics
Geogrids
Geomembranes
Geocomposites
Geonets, Geofibres,mesh mattings,
Geopipes
Woven geotextile
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Non-woven Geotextile
Geogrid Manufacture
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Uniaxial Geogrid
Uniaxial Geogrid
Geogrid Biaxial
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Geonet
Geonet
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Geocomposites
Geosynthetics – composition
Polypropylene
H D P E
Polyester
PVC
Synthetic Rubber
Natural fibres – Jute, coir
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COIR GEOTEXTILES
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Geosynthetics – the functions
Separation
Drainage
Filteration
Reinforcement
Moisture barrier
Cushion
Separation function
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Drainage function
Filtration function
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Reinforcement function
REINFORCEMENT FUNCTION
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Slope Failure
Reinforced Slopes
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Geosynthetic Reinforcement
Geosynthetic Basal Mattress
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Geomembrane Seepage Barrier
Possible Applications Of Geotextiles As
Filters In Fill Dams.
Filter location Purpose of filter
a. Downstream slope protection Control of erosion by rainfall
b. Downstream surface drains. Removal of surface seepage.
c. Upstream slope protection. Control of erosion by wave
action and by outward flow
during drawdown.
d. Temporary internal drainage. Dissipation of excess pore
pressure during construction of
wet fills.
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Possible Applications Of Geotextiles As
Filters In Fill Dams (contd.)
e. Upstream internal fill boundary e.g.
upstream core boundary or foundation
contact.
Prevention of
unacceptable
migration of fines in
upstream direction
f. Downstream interface-no-continuous
flow from reservoir e.g. beneath weight
block.
Prevention of
unacceptable
migration of fines
g. Downstream internal interface-
continuous flow from reservoir, e.g.
down-stream core boundary or
foundation interface near core.
Prevention of internal
erosion, including
effects of
concentrated flow in
cracks etc.
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Use of Geomembranes
In Fill Dams
Enhanced watertightness in concrete
dams
In Rehabilitation of concrete and masonry
dams
Protective layers
Cushion
Anchorage
ICOLD – Geotextiles & Geomembranes
in Dams
1. Geomembrane
2. Geomembrane
underdrain
3. Chimney Drain
4. Finger Drain
outlet
5. Protecting &
weighing
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CASE HISTORIES
Information Sources: CBIP – ICOLD, Geosynthetics in Dam Engineering (Eds.
Varma, C. V. J.; Rao, A. R. G.;Venkatappa Rao, G. ), 1995
CBIP – Use of Geosynthetics in India – Experiences and Potential, A State of Art Report (Eds. Venkatappa Rao, g.; Saxena, K. R. ) Pub. No. 209, 1989
ICOLD – Water-tight Geomembranes for Dams – State of Art, Bulletin No. 78, 1991
IGS - Geosynthetics Case Histories (Eds. Raymond, G. P.; Giroud, J. P. ) 1993
Venkatappa Rao, G. , Erosion Control with Geosynthetics, CBIP , 1995
Engineering with Geosythetics (Eds. Venkatappa Rao, G; Suryanarayana Raju, G. V. S.) Tata McGraw Hill, 1990