2. EARTHEN DAM
•Dams, which are constructed of earth and rock materials,
are generally referred to as embankment dams or fill-type
dams.
•They resist all the forces acting on it by its own weight.
3. NEED…
The construction of EMBANKMENT DAMS is a recent World-Wide
trend in place of concrete Dams.
Because of following ADVANTAGES-
4. TYPES OF EMBANKMENT DAM
EMBANKMENT
DAMS
EARTH-FILL
DAMS
HOMOGENIOUS ZONED DIAPHRAGM
ROCK-FILL
DAMS
CENTRAL CORE INCLINED CORE FACING CORE
6. This type is adopted where dam foundation has a steep inclination along
river and where different construction processes are required for the
construction of Foundation and Core.
7. This type is adopted when there is chances of HIGH SEEPAGE and
SLOPE FAILURE due to different GEOLOGICAL features of the site.
9. FAILURES AND DAMAGES TO EMBANKMENT DAMS
• Failure of the Earthen dam takes place mainly due to the
improper design, selection of construction material and
construction techniques.
•Basic failure CAUSES of embankment DAMS :-
1. Hydraulic Failures (Overtopping, Erosion)
2. Seepage Failures (Piping, sloughing)
3. Structural Failures (Body sliding, foundation failure)
13. 2.Sliding due to Pore-Water Pressure during construction
•An excessive and abrupt increase of pore-water pressure, such as
the one built-up during construction and the residual one due to
rapid drawdown of the reservoir, may cause sliding failures in
embankment.
14. •Distribution of pore-water pressure at a usual stationary flow
changes during rapid drawdown, which causes a high excess pore-
water pressure in the upstream part of the embankment.
3. Excess Pore-Water Pressure due to Rapid
Drawdown
16. 4. Differential Settlement, Deformation
and Cracking
•Many types of differential settlement and associated severe
deformation such as open cracks appear in both dam body and base
foundation, due to compressibility of fill materials and foundation
soils and their relative rigidity.
•Several patterns of differential settlement and open cracks which
dam engineers often encounter in the field is explained below...
19. 5. Embankment Failure due to Liquefaction.
•High excess pore-water pressure is generated during earthquake
by the application of cyclic shear stresses, and large deformation as
well as vertical displacement develops in the foundation. These
deformations generally lead to catastrophic damages due to
overtopping.
20. •Embankment failures caused by strong excitation are classified
into several patterns in their mechanism. Three distinct patterns
of embankment failures due to earthquake excitation are
schematically illustrated here for different types of Embankment
configuration.
1. Homogeneous Earthfill Dam
2. Homogeneous Rockfill Dam
3. Centrally Located Core Type Rockfill Dam
Earthquake Failure Mechanisms
23. INCIDENTS OF DAM FAILURES IN INDIA
LEAKAGE AND/OR WRONG SITE SELECTION*
1) Panshet Dam, Maharashtra [in July, 1961]
Wrong site selection, ultimately resulted in heavy leakage
2) Nanak Sagar Dam, Uttar Pradesh [in August, 1967]
Wrong site selection & design, ultimately resulted in heavy leakage
3) Sampna Dam, Madhya Pradesh [in June, 1964]
Wrong design, ultimately resulted u/s slip of the dam
4) Machchu Dam II, Gujarat [in August, 1979]
Wrong site selection & design, ultimately resulted in overtopping of the dam
24. INCIDENTS OF DAM FAILURES in other parts of
the world:
LEAKAGE AND/OR WRONG SITE SELECTION*
1) Telton Dam, Idaho, USA [in June, 1976]
Wrong site selection & design, ultimately resulted in heavy leakage
2) Waco Dam, Texas, USA [in October, 1961]
Wrong site selection, ultimately resulted in sliding of the dam
