1) The document discusses various topics related to water resource engineering including embankment dams and gravity dams. It covers suitable sites for embankment dams, types of embankment dams, materials used in earthen dams, and causes of embankment dam failures. 2) Needs for dam construction include drinking water, flood control, irrigation, hydroelectric power and more. Embankment dams are built from soil, rock fill, or a composite. Types include earth dams, rock-fill dams, and composite dams. 3) Causes of embankment dam failures include hydraulic failures from overtopping, seepage failures from piping, and structural failures from shear stresses or earthquakes

1. Swami Keshvanand Institute of Technology
Management & Gramothan Jaipur
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SUBJECT: WATER RESOURCE ENGINEERING (WRE)
SITARAM SAINI
ASSISTANT PROFESSOR
DEPARTMENT OF CIVIL ENGINEERING

2. Introduction
Embankment dams:
1) Suitable site.
2) Causes of failures of Embankment dams.
3) Stability analysis of Embankment dams.
4) Seepage analysis of Embankment dams.
5) Flow net through Embankment dams.
6) Principles of design of earth dams.
Gravity dams:
1) Forces acting on gravity dam.
2) Stability requirement of gravity dam.
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3. Needs for Dam Construction:
 Drinking and domestic water supply
 Flood control
 Irrigation
 Industrial water supply
 Hydroelectric energy production
 Retention and control of sediments
 Inland navigation
 Improvement of water quality
 Fish Farming.
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4. Embankment dam:
These dams are built of soil or rock fill or both materials .
These are also called non-rigid dams, because soil & rock fill are
non-rigid materials.
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5. Types of Embankment dams:
1. Earth dam. 2. Rock-fill dam. Composite earth & rock-fill dam.
Earth dam.
Earthen dams can be constructed on almost all types of foundation,
provided suitable measure are taken. They are constructed by using
suitable types of soil.
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6. Materials of Earthen Dams:
Earthen dam require very large quantity of materials.
It is necessary to utilize the soils available in large quantities near the
site.
 In general earth dams can be designed to fulfill its function
satisfactorily with any type of material available.
Materials of Earthen Dams The following material are commonly
used.
Clayey material : Black cotton soil, silty clayey loam, cutoff
Sandy Material : Murum, soft rock, sandy silt, for casting
Rock : For pitching and riprap, rock masonry, etc.
Sand : For filters, seepage drain and masonry.
Other materials : Cement, steel, lime, and other building materials
in small quantities for the construction of spillway, outlets, etc.
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7. Rock fill dams:
Rock-fill dams are embankments of compacted free-draining granular
earth with an impervious zone. The earth utilized often contains a
high percentage of large particles, hence the term "rock-fill". Rock-fill
dams are resistant to damage from earthquakes.
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8. Composite earth& rock fill dam:
Composite dams are combinations of one or more materials which
may small size soil and large size rock particles .
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9. Suitable site for a embankment dam:
 Availability of suitable foundation
 Considerable economy
 Position of spillway
 Area u/s of the dam
 Area d/s of the dam
 Environmental consideration
 Migration of local people
 Good results in overall economy , operation & maintenance
of water resource project.
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10. Causes of failures of Embankment
dams:
1. Hydraulic failure:
2. Seepage failure:
3. Structural failure:
4. Earthquake failure:
5. Foundation slide:
6. Slope protection failure:
7. Damage due to soluble minerals:
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11. Cause of failure of Earthen
Dams:
(1) Hydraulic Failure
Above 40 % of earthen dam failures are due to this reason
only. Hydraulic failures are due to the following reasons:
(i) By over topping
The overtopping of dam may cause due to insufficient
capacity of spillway and insufficient free board or its
spillway gates are not properly operated.
(ii) Erosion of u/s slope
Erosion is caused due to wave action on the upstream
slope and leads to its slip. The slope should be properly
protected by providing pitching
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12. (iii) Cracking due to frost action
Cracks in the upper portion are developed due to frost. It
leads to profuse seepage and consequent failure. In areas
of low temperature additional free board about 1.0 in
should be provided to guard against such failure.
(iv) Erosion of d/s slope
Erosion occurs on the d/s slope due to rain action. If
unchecked, it forms gullies on the d/s face, ultimately
leading to dam failure. This can be avoided by planting at
d/s face by proper maintenance.
( v ) Erosion of d/s toe
The toe of the dam may be eroded due to heavy cross-
current coming from spillway or tail water. The d/s slope
should he protected by providing stone pitching .
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13. (2) Seepage Failure:
More than 33 % of earthen dam failure are due to seepage.
Seepage always occur in earth dams.
It does not harm its stability if it is within the design limits.
But excessive seepage will lead to failure of the dam.
(i) Piping through the body of the dam
It is due to transport of soil particles with seepage flow. It
results in gradual formation of drain from u/s to d/s through
which water, flow sand thus the darn fails.
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14. Seepage Failure :
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Failure of dam due to piping through dam

15. (ii) Piping through foundations
When highly permeable strata of gravel, sand or cavities are
present in the foundation of dams, it permits heavy seepage of
water through it causing erosion of soil which will result in the
formation of piping. Hence, the dam will sink down causing its
failure. Careful investigation of foundations soil and proper will help
in avoiding such failures.
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16. Cause of failure of Earthen Dams
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17. (3) Structural Failures (Shear failures)
About 25 to 30 % of the dam failure are due to this
Reason:
(i) U/S and D/S slopes slide:
The slopes being steeper than required, leads to slips due to stress
strength. The slopes should, therefore, be flat as required from
structural point of view.
(ii) Sudden draw-down:
The sudden draw down in water level of the reservoir causes slips
of u/s slope. The slope should be flat enough to be stable under
sudden drawdown.
(iii)Faulty construction and improper maintenance Wrong
placement of material in different zones Under compaction or over
compaction Blind drains due to mixing of soil. Timely repair of
gullies, rain cuts, settlement, pitching will help for better health of
the dam
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18. Failure by Earthquakes:
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19. Flow-Net :
A flow-net is a graphical representation of two-dimensional
steady-state groundwater flow through soil mass.
It is a grid obtained , if flow lines & equipotential lines cross
at right angle to each other.
The method is often used in civil engineering ,
hydrogeology or soil mechanics as a first check for problems
of flow under hydraulic structures like dams or sheet pile
walls.
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21. Characteristics of Flow –Net:
Flow lines & Stream lines represents flow path of particles of
water
Flow lines and equipotential lines are perpendicular to each other.
area between two flow lines is called flow channel.
The rate of flow in a flow channel is constant
Flow cannot occur across flow lines.
Au equipotential line is a line joining points with same head
The velocity of flow is normal to the equipotential lines.
A How line cannot intersect another flow line
An equipotential line cannot intersect another equipotential
line.
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22. Reference
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Irrigation and water power engineering
Dr B. C. Punmia
Dr K.r.arrora.
Arun kr. Jain
Ashish ku. jain
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