Design of Kawlewada Dam and its Components.

A PROJECT REPORT ON
" DESIGN OF KAWLEWADA DAM AND ITS
COMPONENTS "
Submitted to Sant Gadge Baba Amravati University, Amravati in Partial Fulfillment of the
Requirements for the Degree of BACHELOR OF TECHNOLOGY in
CIVIL ENGINEERING
By
Ujwal B. Kurzekar (17001001) Raj V. Bisen (17001011)
Anvesh R. Modak (17001013) Yash P. Pilliwar (17001027)
Uddesh D. Shende (17001042) Sachin D. Mosambe(17001046)
Guide
Dr. S. P. TATEWAR
HEAD
DEPARTEMNT OF CIVIL ENGINEERING
DEPARTMENT OF CIVIL ENGINEERING
GOVERNMENT COLLEGE OF ENGINEERING,
AMRAVATI – 444604
2020-2021

i
GOVERNMENT COLLEGE OF ENGINEERING, AMRAVATI
(AN AUTONOMOUS INSTITUTE OF GOVERNMENT OF MAHARASHTRA)
DEPARTMENT OF CIVIL ENGINEERING
CERTIFICATE
This is to certify that the project report entitled, “Design of Kawlewada Dam and its
Components” which is being submitted here with for the award of B.Tech Civil
Engineering is the result of the work completed by: -
Anvesh R. Modak (17001013) Yash P. Pilliwar (17001027)
Uddesh D. Shende (17001042) Sachin D. Mosambe (17001046)
under my supervision and guidance. The work embodied in this report has not formed earlier
as the basis of the award of any degree or compatible certificate or similar title of this for any
other diploma/examining body or university to the best of knowledge and belief.
Dr. S. P. TATEWAR
Guide & Head
Department of Civil Engineering
Government College of Engineering,
Amravati
Dr. R. P. BORKAR
Principal
Government College of Engineering,
Amravati

ii
DECLARATION
We hereby declare that we have formed, completed and written the report entitled
“Design of Kawlewada Dam and its Components” has been exclusively carried out and
written by us under the guidance of Dr. S. P. Tatewar, Department of Civil Engineering,
Government College of Engineering, Amravati. This work has not been previously formed
the basis for the award of any degree or diploma or other similar title of this for any other
diploma/examining body or university.
Place: Amravati
Date:
Submitted By
Anvesh B. Modak (17001013) Yash P. Pilliwar (17001027)
Uddesh D. Shende (17001042) Sachin D. Mosambe (17001046)

iii
ACKNOWLEDGEMENT
It is our duty and desire to express acknowledgement to the various torch bearers, who
have rendered valuable guidance during the preparation of this report.
We sincerely acknowledge our indebtedness to guide and HoD, Prof. Dr. S. P.
TATEWAR for his guidance and immense support on every step towards the completion
of the project. His critical comments, advice and guidance have been very valuable to us.
Above all, we are highly grateful for his timely and detailed corrections. We are also
thankful for his patience,understanding and encouragement.
We would also like to express our deep sense of gratitude and sincere regards to Prof.
Dr. R.P. BORKAR, Principal, Government College of Engineering, Amravati.
Ujwal B. Kurzekar (17001001)
Raj V. Bisen (17001011)
Anvesh R. Modak (17001013)
Yash P. Pilliwar (17001027)
Uddesh D. Shende(17001042)
Sachin D. Mosambe (17001046)

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ABSTRACT
Through, the demanding years, it has been observed that failures of dams due to many
factors are common. So it is the very essential to analyse the dam against all modes of
failures, calculate forces acting on it, predict uncontrollable disasters such as
earthquake, disaster, etc. For this, the preliminary data of the dam required for design,
such as control levels, dimensions, crest width, base width, etc. was collected through
the Inspection Engineer, posted at Dhapewada Lift Irrigation Office, Tiroda, Gondia.
On the basis of collected data the elementary profile and practical profile of dam was
estimated, further all the major and the minor forces acting on dam were calculated,
stability analysis of designed dam against all modes of failure and for various load
combinations was carried out in MS-EXCEL & STAAD PRO softwares and was
checked for permissible limits. Design of spillway, stilling basin and earthen dam was
also carried out for the designed dam. Further, canal originating from the dam and
carrying water to culturable command area was also designed by taking care of peak
discharge as required by crops.

v
TABLE OF CONTENT
Chapter No. Title Page No.
Certificate i
Declaration ii
Acknowledgement iii
Abstract iv
List of Figures vii
List of Tables ix
List of Abbreviations x
Nomenclature ⅹi
1 Introduction
1.1. General 1
1.2. Introduction To Dams 1
1.3. Methodology 7
1.4 Organization of Report 20
2 Literature Review
2.1 Introduction 21
2.2 Literature Review
21
2.3 Conclusion 23
3 Hydrology And Hydraulic Engineering Aspect
3.1 Rainfall Data for Region 24
3.2 Calculation of Annual Inflow 26
3.3 Calculation of Annual Outflow 26
3.4 Controlling Levels 28
3.5 Salient Features of Reservoir 28
4 Analysis of Gravity Dam
4.1 Elementary Profile of The Dam 29
4.2 Practical Profile of The Dam 32
4.3 Calculation of Forces Acting on The Dam and Stability
Analysis of This Dam
35
4.4 Analysis of Dam in STAAD PRO Software
59
5 Design of Components of Gravity Dam

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5.1 Design of Spillway 80
5.2 Design of Stilling Basin
86
5.3 Design of Earthen Dam
92
5.4 Design of Canals
96
6 Conclusion
6.1 Objectives 104
6.2 Conclusion 104
6.3 Future Scope of Present Study 105
References 106
Appendix: Research Paper 107

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LIST OF FIGURES
Figure
no
Title
Page
no
1.1 Forces acting on dam 8
1.2 Wave pressure 12
1.3 Variation of pressure along depth 15
3.1 Rainfall statistics of region 24
4.1 Elementary profile of dam 29
4.2 Practical profile of dam 33
4.3 Calculated practical profile of dam 35
4.4 Typical section of gravity dam. 35
4.5 Forces on upstream side 36
4.6 Forces on downstream side 37
4.7 Uplift pressure without drainage gallery 38
4.8 Uplift pressure with drainage gallery 39
4.9 Diagram of C.G. calculation 40
4.10 Photo insight of gallery of gravity dam 51
4.11 Type of gallery 52
4.12 Provision of drainage gallery 52
4.13 Dam section 64
4.14 3D rendered view 65
4.15 Construction condition 66
4.16 Flood discharge representation 67
4.17 Combination earthquake force representation 68
4.18 Extreme uplift force representation 69

viii
4.19 Load combination A 71
4.20 Load combination B 72
4.21 Load combination C 74
4.22 Load combination D 75
4.23 Load combination E 76
4.24 Load combination F 78
4.25 Load combination G 79
5.1 Spillway of dam 81
5.2 Ogee spillway 82
5.3 Practical profile of ogee spillway 85
5.4 I.S. stilling basin type 1 87
5.5 I.S. stilling basin type 2 87
5.6 Design of stilling basin 88
5.7 Type 2 stilling basin 90
5.8 Downstream of earthen dam 95
5.9 Section of an earthen dam 95
5.10 Canal head regulator 97
5.11 Section of canal 99
5.12 Flow chart for design 99
5.13 Cross section of canal 102

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LIST OF TABLES
Table no. Title Page no.
1.1 Factor of safety against sliding 18
4.1 Moment about toe of elementary profile 30
4.2 Forces and moment w.r.t. toe of gravity dam 43
4.3 Node points 62
4.4 Thickness, material and supports 63
4.5 Combination of load cases 64
5.1 Water requirement of crops 96
5.2 Canal Discharge and command area 98
5.3 Surface and roughness coefficient 100
5.4 Side slope of lining canal 100
5.5 Hydraulically effective cross section and dimension 100

x
LIST OF ABBREVIATIONS
Sr. No. Abbreviation Description
1 C.G Centre Of Gravity
2 ET Evapotranspiration
3 F.R.L Full Reservoir Level
4 F.S Factor Of Safety
5 Fig Figure
6 I.O.I Intensity Of Irrigation
7 IS Indian Standard
8 Kmph Velocity In Kilometers Per Sec
9 Lpcd Liter Per Capita Per Day
10 M.W.L Minimum Water Level
11 R.L Reduced Level
12 RCC Roller Compacted Concrete
13 S.F.F Shear Friction Factor
14 T.W.L Tail Water Level
15 T.W.S Tail Water Side
16 U.S.B.R United States Bureau Of Reclamation

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NOMENCLATURE
Sr. No. Notations Description
1 U/S upstream
2 D/S Downstream
3 Ɣ Unit weight
4 Ɣc Unit weight of concrete
5 Ɣw Unit weight of water
6 V Velocity of wind in kmph
7 KNm Kilo newton meter
8 U Uplift pressure
9 W weight
10 Ha hectares
11 P Water pressure
12 Sc Specific weight of concrete
13 f Permissible compressive stress of dam materials
14 hw Height of wave
15 Ps Silt pressure force
16 Mo Overturning moment
17 MR Resisting moment
18 e eccentricity
19 X Level arm
20 𝜎𝑑 Direct stress
21 𝜎𝑏
Bending stress
22 Fr Froude number
23 Cd Coefficient of discharge
24 Le Clear waterway
25 g Acceleration due to gravity
26 T Mean arrival temperature
27 Q Yield in cm
28 ka Coefficient of active earth pressure
29 kp Coefficient of passive earth pressure
30 yc Critical depth

Design of Kawlewada Dam and its Components Page 1
Chapter 1
INTRODUCTION
1.1 General
Wainganga is one of the major rivers of Vidharbha region and is tributary of river
Pranhita in Godavari basin. The river originate near river Pratapgarh in Seoni district
of Madhya Pradesh and enters into Maharashtra near village Birsola of taluka and
district Gondia and flows down to south through Bhandara, Nagpur, Chandrapur and
Gadchiroli district. The total length of the river is 717 km. The total catchment up to
proposed site is 4736.70sq.km. The Concrete gravity dam and its, components are
designed based on reservoir of river Wainganga and some preliminary data necessary
for design is taken from Kawlewada dam.
The Data of reservoir along with plan of dam were collected from Dhapewada Lift
irrigation Office situated in tirora Dist. Gondia (MH). The Kawlewada Dam is located
in Tirora tahsil of Gondia district near Kawlewada. The proposed site is 2 km away
from village Kawlewada which is 6 km away from taluka place i.e. Tirora. Tirora is
89km away from Nagpur which is second capital of Maharashtra. This is well
connected by air and road. The proposed site is located on longitude 79°48’50” and
latitude 29°21;16”.
1.2 Introduction to Dams
Definition: A dam is a hydraulic structure of fairly impervious material built
across a river to create a reservoir on its upstream side for impounding water for
various purposes. It is a barrier that impounds water or underground streams.
Dams generally serve the primary purpose of retaining water. Dams are probably
the most important hydraulic structure built on the rivers. These are very huge
structure and require huge money, manpower and time to construct. Dams are
generally constructed in the mountainous reach of the river where the valley is
narrow and the foundation is good. Water is essential for sustenance of all forms
of life on earth. It is not evenly distributed all over the world and even its

availability at the same locations is not uniform over the year. While the parts of
the world, which are scarce in water, are prone to drought, other parts of the
world, which are abundant in water, face a challenging job of optimally managing
the available water resources. No doubt the rivers are a great gift of nature and
have been playing a significant role in evolution of various civilizations,
nonetheless on many occasions, rivers, at the time of floods, have been playing
havoc with the life and property of the people. Management of river waters has
been, therefore, one of the most prime issues under consideration. Optimal
management of river water resources demands that specific plans should be
evolved for various river basins which are found to be technically feasible and
economically viable after carrying out extensive surveys. Since the advent of
civilization, man has been constructing dams and reservoirs for storing surplus
river waters available during wet periods and for utilization of the same during
lean periods. The dams and reservoirs world over have been playing dual role of
harnessing the river waters for accelerating socio-economic growth and
mitigating the miseries of a large population of the world suffering from the
vagaries of floods and droughts.
Dams and reservoirs contribute significantly in fulfilling the following basic
human needs: -
1. Water for Drinking and Industrial Use
2. Irrigation
3. Flood Control
4. Hydro Power Generation
1. Water supply for domestic and industrial use –
It has been stressed how essential water is for our civilization. It is important to
remember that of the total rainfall falling on the earth, most falls on the sea and a large
portion of that which falls on earth ends up as runoff. Only 2% of the total is
infiltrated to replenish the groundwater. Properly planned, designed and constructed
and maintained dams to store water contribute significantly toward fulfilling our
water supply requirements. To accommodate the variations in the hydrologic cycle,
dams and reservoirs are needed to store water and then provide more consistent
supplies during shortages.

1. Irrigation by dam – Dams and reservoirs are constructed to store surplus waters
during wet periods, which can be used for irrigating arid lands. One of the major
benefits of dams and reservoirs is that water flows can be regulated as per
agricultural requirements of the various regions over the year. Dams and
reservoirs render unforgettable services to the mankind for meeting irrigation
requirements on a gigantic scale. It is estimated that 80% of additional food
production by the year 2025 would be available from the irrigation made possible
by dams and reservoirs. Dams and reservoirs are most needed for meeting
irrigation requirements of developing countries, large parts of which are arid
zones. There is a need for construction of more reservoir based projects despite
widespread measures developed to conserve water through other improvements in
irrigation technology.
A major portion of water stored behind dams in the world is withdrawn for
irrigation which mostly comprises consumptive use, that is, evapotranspiration
(ET) needs of irrigated crops and plantations. On the submerged land, there are
often possibilities for seasonal irrigation. A majority of dams built in the world are
multipurpose in nature, but irrigation is the largest user of the waters withdrawn.
This does not necessarily mean that irrigation is also the biggest user of storage.
2. Inland navigation – Natural River conditions, such as changes in the flow rate
and river level, ice and changing river channels due to erosion and sedimentation,
create major problems and obstacles for inland navigation. The advantages of
inland navigation, however, when compared with highway and rail are the large
load carrying capacity of each barge, the ability to handle cargo with large-
dimensions and fuel savings. Enhanced inland navigation is a result of
comprehensive basin planning and development utilizing dams, locks and
reservoirs which are regulated to provide a vital role in realizing regional and
national economic benefits. In addition to the economic benefits, a river that has
been developed with dams and reservoirs for navigation may also provide
additional benefits of flood control, reduced erosion, stabilized groundwater levels
throughout the system and recreation.

3. Flood control – Dams and reservoirs can be effectively used to regulate river
levels and flooding downstream of the dam by temporarily storing the flood
volume and releasing it later. The most effective method of flood control is
accomplished by an integrated water management plan for regulating the storage
and discharges of each of the main dams located in a river basin. Each dam is
operated by a specific water control plan for routing floods through the basin
without damage. This means lowering of the reservoir level to create more storage
before the rainy season. This strategy eliminates flooding. Flood control is a
significant purpose for many of the existing dams and continues as a main purpose
for some of the major dams of the world currently under construction.
4. Hydropower – Electricity generated from dams is by very far the largest renewable
energy source in the world. More than 90% of the world's renewable electricity
comes from dams. Hydropower also offers unique possibilities to manage the
power network by its ability to quickly respond to peak demands. Pumping-
storage plants, using power produced during the night, while the demand is low, is
used to pump water up to the higher reservoir. That water is then used during the
peak demand period to produce electricity. This system today constitutes the only
economic mass storage available for electricity. In ancient times, dams were built
for the single purpose of water supply or irrigation. As civilizations developed, there
was a greater need for water supply, irrigation, flood control, navigation, water quality,
sediment control and energy. Therefore, dams are constructed for a specific purpose such
as water supply, flood control, irrigation, navigation, sedimentation control, and
hydropower. A dam is the cornerstone in the development and management of water
resources development of a river basin. The multipurpose dam is a very important project
for developing countries, because the population receives domestic and economic
benefits from a single investment.
➢ Different types of dams –
Dams can be classified on the basis of following points –
1. Based on use of dam.
2. Based on hydraulic design.

3. Based on material of construction.
4. Based on mode of resistance offered by dam against external Forces.
1. Based on use of dam -
a. Storage dam: They are constructed to store water during the rainy season when
there is a large flow in the river. Many small dams impound the spring runoff for
later use in dry summers. Storage dams may also provide a water supply, or
improved habitat for fish and wildlife. They may store water for hydroelectric
power generation, irrigation or for a flood control project. Storage dams are the
most common type of dams and in general the dam means a storage dam unless
qualified otherwise.
b. Diversion dam: A diversion dam is a dam that diverts all or a portion of the flow
of a river from its natural course. Diversion dams do not generally impound water in
a reservoir. Instead, the water is diverted into an artificial water course or canal,
which may be used for irrigation or return to the river after passing through
hydroelectric generators, flow into a different river or be itself dammed forming a
reservoir. The earliest diversion dam—and the second oldest dam of any kind
known—is the Ancient Egyptian Sadd el-Kafara Dam at Wadi Al- Garawi, which
was located about twenty-five kilometers south of Cairo. Built around 2600 BC
c. Water spreading dam: These are low height dam whose main objective is to
recharge ground water.
d. Debris dam: A debris dam is constructed to retain debris such as sand, gravel, and
drift wood flowing in the river with water. The water after passing over a debris
dam is relatively clear.
2. Based on hydraulic design-
a. Non overflow dam: It is constructed such that water is not allowed to overflow
over its crest. In most cases, dams are so designed that part of its length is
designed as an overflow dam (this part is called the spillway) while the rest of its
length is designed as a non-overflow dam. In some cases, these two sections are
not combined.
b. Overflow dam: It is constructed with a crest to permit overflow of surplus water
that cannot be retained in the reservoir. Generally, dams are not designed as
overflow dams for its entire length. Diversion weirs of small height may be

designed to permit overflow over its entire length.
3. Based on material –
a. Rigid dam: It is constructed with rigid material such as stone, masonry, concrete,
steel, or timber. Steel dams (steel plates supported on inclined struts) and timber
dams (wooden planks supported on a wooden framework) are constructed only for
small heights (rarely). Ex. Steel dam, Timber dam.
b. Non rigid dam: It is constructed with non-rigid material such as earth, tailings,
rock fill etc. Ex. Earthen dam, Rock fill, Rubber dam.
4. Based on mode of resistance –
a. Gravity dam: A gravity dam is a massive sized dam fabricated from concrete and
designed to hold back large volumes of water. By using concrete, the weight of the
dam is actually able to resist the horizontal thrust of water pushing against it. This is
why it is called a gravity dam. Gravity essentially holds the dam down to the ground,
stopping water from toppling it over. Gravity dams are well suited for blocking rivers in
wide valleys or narrow gorge ways. Since gravity dams must rely on their own weight to
hold back water, it is key that they are built on a solid foundation of bedrock. In fact, an
earth rock fill dam is a gravity dam. Straight gravity dam – A gravity dam that is straight
in plan. Curved gravity plan – A gravity dam that is curved in plan. Curved gravity dam
(Arch gravity dam) – It resists the forces acting on it by combined gravity action (its own
weight) and arch action. Solid gravity dam – Its body consists of a solid mass of masonry
or concrete Hollow gravity dam – It has hollow spaces within its body. Most gravity dams
are straight solid gravity dams.
b. Arched dam: It is a curved masonry or concrete dam, convex upstream, which
resists the forces acting on it by arch action. transfers the water pressure and other
forces mainly to the abutments by arch action. These type of dams are concrete or
masonry dams which are curved or convex upstream in plan 1. Its shape helps to
transmit the major part of the water load to the abutments 2. Arch dams are built
across narrow, deep river gorges, but now in recent years they have been
considered even for little wider valleys.
c. Buttress dam: It consists of water retaining sloping membrane or deck on the u/s
which is supported by a series of buttresses. These buttresses are in the form of
equally spaced triangular masonry or reinforced concrete walls or counterforts.

The sloping membrane is usually a reinforced concrete slab. In some cases, the u/s
slab is replaced by multiple arches supported on buttresses (multiple arch buttress
dam) or by flaring the u/s edge of the buttresses to span the distance between the
buttresses (bulkhead buttress dam or massive head buttress dam). In general, the
structural behavior of a buttress dam is similar to that of a gravity dam.
1.3 Methodology
The gravity dam has to maintain its stability against the loads from its structural
mass and strength of concrete. The loads assumed on the concrete dam for stability
analysis are water pressure, uplift force, wind force, wave pressure, silt pressure, self-
weight. To withstand the stability of concrete gravity dam, the dam has to be safe with
the overturning force on dam, sliding force, compression and tension. The concrete
gravity dam gets cracks easily by its upstream and downstream sides of the dam
because of internal and external temperature changes and by earthquakes. This cracks
causes to the failure of the dam in the static and dynamic conditions of the dam.
1.3.1 Force Acting on Gravity Dam
1. Water Pressure
2. Uplift Pressure
3. Self-Weight of Dam.
4. Wave Pressure
5. Earthquake Pressure
6. Silt Pressure
7. Wind Pressure
8. Ice Pressure
Out of above eight forces, acting on the dam, first three forces are the major forces
that are considered in the design. All other forces are not of much significance and are
considered only under specific conditions.

A detailed sketch of a gravity dam is shown in below Fig. All the predominant forces
that act on the dam have been shown in the figure itself
Fig 1.1- Forces acting on dam
1. Water pressure: The hydraulic pressure is a horizontal force, acts on the dam in
the form of triangular shape. At the surface of reservoir the water exerts no
pressure and at the bottom (at toe) the water exerts maximum amount of pressure
to dam. This is the largest external force acting on the dam. It has the largest
capacity for disturbing the stability of the dam. It is a horizontal force which acts
at the C.G. of the pressure distribution diagram, due to water. The pressure
distribution diagram is always triangular with zero value at surface of the water
and increasing linearly to maximum at the base of the dam.
Water pressure = ½ γw.ℎ2,
acts on ℎ/3height from the water base.

2. Uplift pressure: The water that seeps through the pores of the material comprising
dam and foundation, causes uplift pressure and tries to tilt or topple the dam. A part of
the weight of the dam would get neutralized by uplift pressure and thus net foundation
reaction due to vertical forces will be reduced. Intensity of uplift pressure is maximum
at U/ S end of the dam and it goes on decreasing towards the D/S end. As some water
can see into the concrete dam also, the uplift pressure may occur anywhere in the dam
also. It is very difficult to find out the value of uplift pressure accurately. It depends
upon the factors like, cut off on U/S side, fissures in the foundation rocks, drain
ability of the foundation etc. There are two schools of thought as to on how much area
uplift pressure should be considered as acting. According to one thought one-third to
two-third area of foundation should be considered effective. The second thought,
propagated by Terzaghi recommends consideration of full area as the effective area.
U.S.B.R. Recommendations:
According to U.S.B.R., intensity of uplift pressure at D/S (Toe) and U/S (heel)
is taken equal to the hydrostatic pressure of water. The variation of uplift
pressure from heel to toe is linear or straight line. In order to release uplift
pressure, drainage galleries are provided in the body of the dam. The
magnitude of the uplift pressure at the face of the gallery is taken as equal to
hydrostatic pressure at the Toe plus one third the difference of the hydrostatic
pressures at the heel and Toe.
Uplift pressure at heel = wh
Uplift pressure at toe = wh’
Uplift pressure at gallery point G = w [h’ +1/3 (h- h’)]
The following criteria are recommended for the calculation of uplift forces:
a. Uplift pressure distribution in the body of the dam shall be assumed, in case of
both preliminary and final design, to have an intensity which at the line at the
formed drains exceeds the tail water pressure by one-third the differential between
reservoir level.
The pressure gradient shall then be extending linearly to heads corresponding to
reservoir level and tail water level.

b. Uplift pressure distribution at the contact plane between the dam and its
foundations and within the foundation shall be assumed for preliminary designs to
have an intensity which at the line of drains exceeds the tail water pressure by one-
third the differential between the reservoir and tail water heads.The pressure
gradient shall then be extended linearly to heads corresponding to the reservoir
level and tail water level. The uplift shall be assumed to act over 100 per cent
area. For final designs, the uplift criteria in case of dams founded on compact and
un-fissured rock shall be as specified above.In case of highly jointed and broken
foundation, however, the pressure distribution may be required to be based on
electrical analogy or other methods of analysis taking into consideration the
foundation condition after the treatment proposed. The uplift shall be assumed to
act over 100 per cent of the area.
c. For the extreme loading conditions F and G given later the uplift shall be taken as
varying linearly from the appropriate reservoir water pressure at the U/S face to
the appropriate tail water pressure at the D/S face. If the reservoir pressure at the
section under consideration exceeds the vertical normal stress (computed without
uplift) at the U/S face, horizontal crack is assumed to exist and to extend from the
U/S face towards the D/S face of the dam to the point where the vertical normal
stress (computed on the basis of linear pressure distribution without uplift) is
equal to the reservoir pressure at the elevation.
d. No reduction in uplift is assumed at the D/S toe of spillways on account of the
reduced water surface elevation (relative to normal tail water elevation) that may
be expected immediately downstream of the structure.
e. It is assumed that uplift pressures are not affected by earthquakes.
2. Self-weight of dam:
It is the most important force, particularly for gravity dams. Stability of the dam
largely depends upon this force. For the design purpose only unit length of the dam is
considered.
Cubic content of the cement concrete is determined for unit length of the dam. This
cubic content when multiplied by the density, gives the total weight (W) of the dam.
The weight of the dam body and its foundation is the major resisting force. In two-
dimensional analysis of a gravity dam, a unit length of the dam is considered. The

cross-section can then be divided into rectangles and triangles. The weight of each
along with their centers of gravity can be determined. The resultant of all these
downward forces will represent the total weight of the dam acting at the center of
gravity of the dam.
Self-weight Sw = lbh.ρc.g
Where, ρc is density of concrete= 2400 𝑘𝑔
3. Wave pressure:
Waves develop on the surface of the reservoir due to wind. The waves exert pressure
on the dam. The magnitude of wave pressure depends upon the height of the waves,
developed in the reservoir.
Where, hw = Height of wave in meters from trough to crest.
V = Wind velocity in km per hour.
F = Fetch or straight length of water expanse in km.
After having found out the value of hw the pressure intensity due to wages is found
out by formula pw = 2.4 w hw (t/m2).
The pw is considered as acting at hw/ 8 meters above the still water surface.
The pressure distribution due to wave pressure is curved but for all design purposes it
is considered as triangular as shown in Fig.

Fig 1.2- Wave Pressure
The height of the triangle is not considered as hw but (5/3) * hw. Hence total
pressure pw due to waves is given by –
4. Earthquake Pressure:
Primary, secondary, Releigh and Love waves, are set up in the earth’s crust, due to
earthquakes. These waves impact acceleration to the foundation under the dam and
cause its movement. In order to prevent cracking or rupture, the dam must also move
along with the movements of the foundation. The acceleration generated due to
earthquake develops inertia force in the dam, due to which, stresses are first induced
in lower layers and then in whole of the dam. The earthquake waves can travel in any
direction. They are however resolved in vertical and horizontal directions.
The effects of acceleration in horizontal and vertical directions are given as follows:
A. Effect in Vertical Direction:
Due to vertical component of acceleration, a vertical inertia force F = αW is
developed on the dam. The direction of this force is in opposite direction to the

acceleration. In other words, inertia force acts downwards when acceleration is
upwards, thus increasing the downward weight momentarily.
Similarly, when acceleration is vertically downwards the inertia force F = αW acts
upwards, thus decreasing the downward weight temporarily. Hence unit weight of the
dam and water get altered as follows, due to vertical acceleration.
For dam material = We (1 ± α)
For water = w (1 ± α)
Where we = unit weight of dam material, α = acceleration.
B. Effect in Horizontal Direction
Two forces are developed due to horizontal effect of acceleration.
a. Inertia force in dam
b. Hydrodynamic pressure of water.
a. Inertia Force:
Inertia force is equal to the product of the mass of the dam and
the acceleration. F = Mass x acceleration
Where F = Inertia force
W = Weight of the dam
α = Acceleration coefficient
g = Acceleration due to gravity.
Mass = W/g
And acceleration = α g.
∴ F = (W/g) x αg = W α
Inertia force acts in a direction opposite to the acceleration imparted by earthquake
forces. This force should be considered at the C.G. of the mass regardless of the shape
of the cross- section and acts horizontally downstream.

b. Hydrodynamic Pressure:
Horizontal acceleration towards the reservoir causes a momentary increase in water
pressure. The theoretical computations reveal that the distribution of hydrodynamic
pressure due to earth on the upstream face of the dam is elliptical-cum-parabolic. The
following formula of U.S.B.R. and given by C.N. Zargar may be used to evaluate
pressure intensity at a depth y below the maximum water level –
Where, Pey = Intensity of hydrodynamic pressure
a = Acceleration coefficient
w = Unit weight of water
h = Depth of water in the reservoir
Cy = a dimensionless pressure coefficient at a depth y below water level the
of Cy is found out by formula –
Where,
h = Maximum depth of water in the reservoir
y = Depth from the reservoir surface to the elevation in question.
Cm = Maximum value of the pressure coefficient for a given constant slope
= 0.73*(θ/90)
θ = Angle in degrees that the slope of the U/S face of the dam makes with the
horizontal

Fig 1.3-The variation of pressure along the depth
If the U/S face of the dam is inclined, but inclination does not extend to more than
half the depth of the reservoir, the face may be considered as vertical for computation
of Cm. If slope extends to more than half the depth, overall slope θ should be
considered up to full reservoir level for finding the value of Cm as shown in Fig.
5. Silt pressure: The silt gets deposited to the upstream side of the water. The
weight and the pressure of the submerged silt are to be considered in addition to
weight and pressure of water. The weight of the silt acts vertically on the slope
and pressure horizontally. It is compute by the Rankin’s formula.
According to U.S.B.R. recommendation which are mostly followed in the
design, pressure due to silt is considered as fluid pressure which develops a
horizontal pressure with its density as 360 kg/m3 and a vertical pressure
with its density equal to 920 kg/m3, so that additional pressure in horizontal
and vertical directions are as follows –

Increase in silt pressure due to earthquake is generally not considered.
According to IS: 6512-1972 the silt pressure and water pressure exist together in
submerged silt. The following criteria are recommended for calculating forces due to
silt:
a. Horizontal ‘silt and water pressure’ is assumed to be equivalent
to that of a fluid weighing 1360 kg/m3.
b. Vertical ‘silt and water pressure’ is found as if silt and water together
have a density of 1925 kg/m3.
6. Wind Pressure:
It is generally not considered in the design. If it has to be considered, it should
be considered only on that portion of the superstructure which is exposed to
wind. It is normally taken as 100 to 150 kg/m2, acting on the exposed area.
7. Ice Pressure:
This pressure is considered only when dams are located either at very high altitudes or
in very cold regions. In very cold conditions, the reservoir gets covered with a layer of
ice. When this layer is subjected to expansion and contraction due to variation in
temperature, a force is developed which acts on the dam at level of water in the
reservoir.
This force acts linearly along the length of the dam at the reservoir level. The average
magnitude of this force may be taken as 5 kg cm2 of the contact area of the ice layer
with U/S face of the dam. The thermal expansion of ice is about five times that of
concrete.

1.3.2 Modes of Failure of Gravity Dams
A gravity dam can fail due to the following reasons:
1. Overturning of the dam
2. Sliding of the dam
3. Crushing of the dam or Foundation
4. Development of tension in the dam.
1. Overturning of the Dam.
i. If the resultant of all the possible forces (internal as well as external)
acting on the dam cuts the base of the dam downstream of the Toe, the
darn would overturn unless it can resist tensile stresses.
ii. To safeguard the dam against overturning, the resultant of the forces should
never be allowed to go down stream of the Toe.
iii. If resultant is maintained within the body of the dam, there will be no
overturning.
iv. All the forces acting on the dam cause moments.
v. Some of the forces help maintain stability of the dam, while others try to
disturb the stability.
vi. The moments of the forces, helping dam to maintain its stability
vii. The moments of the forces that try to disturb the stability of the dam are
known as overturning moments (Mo).
viii. As soon as Mo exceeds Mr overturn of the dam would take place. Factor of
safety (F.S.) against overturning can be found out as follows.
The value of F.S. against overturning should not be less than 1.5.
2. Sliding of the Dam.
i. In this mode of failure, the dam fails in sliding.
ii. The dam as a whole slide over its foundation or one part of the dam
may slide over the part of the dam itself, lying below it.
iii. This failure occurs when the horizontal forces causing sliding are more than
the resistance available to it, at that level.
iv. The resistance against sliding may be due to friction alone or it may be due
to a combination of friction and shear strength of the joint. Shear strength
develops at the base if benched foundation is provided.
v. At other joints the shear strength is developed by laying joints carefully so as

to obtain good bond.
vi. Interlocking of stone blocks in stone masonry also helps increase shear
strength.
vii. In case of low masonry dams shear strength is not taken into account.
viii. In that case factor of safety against sliding is obtained by dividing net
vertical forces by net horizontal forces and multiplying the resultant by
coefficient of friction μ.
Safety−factor (F.S.) = μΣ(V−u)
ΣH
Where,
µ = Coefficient of friction.
∑ (V – U) = Net vertical force.
∑H = Sum of the horizontal forces causing sliding
The value of coefficient of friction varies from 0.65 to 0.75. The value of F.S. should
always be greater than one. In case of large high dams, the shear strength of the joint
should also be considered along with static coefficient of friction.
In this case factor of safety is known shear friction factor (S.F.F.) Hence Where,
µ∑ (V – U) and ΣH are the same as stated earlier.
b = Width of the joint or section.
q = Shear strength of the joint which is usually taken as 14 kg/cm2. From a
safety point of view, the value of shear friction factor (S.F.F.) should lie
between 4 and 5. The factor of safety against sliding and shear friction factor
as per IS: 6512–1972 are as follows.
Table 1.1. Factor of safety against sliding
Sr.No. Load In Condition Factor of Safety
Against Sliding
Shear Friction
Factor
1. A, B, C 2.0 4.0
2. D, E 1.5 3.0
3. F, G 1.2 1.5
3. Crushing or Compression Failure.
i. If the compressive stress developed anywhere in the dam exceeds the
safe permissible limit, the dam may fail by crushing of the dam itself
or of foundation.

ii. The maximum compressive stress can develop at toe when reservoir is full
of water.
iii. If reservoir is empty, the maximum compressive stress is likely to
develop at the heal of the dam.
iv. The magnitude of maximum compressive and minimum compressive
stresses can be found out by using following equation.
Pn = (1 +
6𝑒
)
𝑏
Where,
pn = Value normal stress. V = Total vertical force.
b = Width of the dam base at level of consideration.
e = Eccentricity of resultant force R from the center of the base.
H = Total horizontal force. R = Resultant force.
Plus, sign is used to evaluate the amount of maximum compressive stress which
will occur at Toe of the dam when reservoir is full and at heel when reservoir is
empty.
4. Failure due to Development of Tension.
i. Both cement concrete and masonry, are very weak in tension.
ii. Hence from safety point of view the tension is not allowed to be
developed in the dam anywhere.
iii. We know that minimum compressive stress in the dam.
iv. The nature of this stress remains
v. Negative sign of this stress indicates that nature of this stress is tensile
rather than compressive.
vi. Hence as soon as e exceeds 6 b tension is developed in the dam and dam
fails by opening of the joints, as concrete and masonry are almost nil in
tension.
vii. When reservoir is full of water, tension is likely to develop at heal and
when reservoir is empty tension is likely to develop at Toe of the dam.
viii. In other words, it can be stated that until resultant of the forces lies
within the middle third width of the base tension cannot develop
anywhere in the dam.
ix. In the case of gravity dams, having moderate height, no tension is
allowed to be developed anywhere.
x. However, in case of very high dams, a small tensile stress may be
permitted to be developed, but only for short durations during heaving
floods or earthquakes.

xi. Once tensile cracks develop at heel, the dam cannot be rendered safe.
xii. Due to tension cracks, uplift pressure gets increased and consequently
net vertical downward force is reduced.
xiii. This causes further shifting of the resultant towards the Toe and this
leads to further lengthening of the cracks.
xiv. Due to lengthening of the cracks, effective width of base is further
reduced and compressive stress at toe further increases.
1.4 Organization of report
The report comprises the following structure on stability analysis of kawlewada dam
and design of its components
Chapter 1: Introduction
Chapter 2: Literature surveys showing the various contribution and the work carried
out by various researches and institute related to the project
Chapter 3: Hydrology and hydraulic engineering aspect dealing with design
catchment yield, gross storage of dam and hydraulic aspect surrounding the dam site.
Chapter 4: Analysis of gravity dam dealing with analysis of different force and
moment acting on dam by STAAD pro.
Chapter 5: Design of components of gravity dam dealing with design of spillway,
stilling basin, earthen dam and canal etc.
Chapter 6: Conclusion showing the concluding action of the project stating the final
result and future scope of the project.
References showing the several websites, books, paper referred to accomplish the
project.
Research paper is included at end of report.

Chapter 2
LITERATURE REVIEW
2.1 Introduction
Literature Survey is an assignment of previous task done by some authors and
collection of information or data from research papers published in journals to
progress our task. It is a way through which we can find new ideas, concept. There are
lot of literatures published before on the same task; some papers are taken into
consideration from which idea of the project is taken.
2.2 Literature review
Moftakhar and Ghafouri [1] (2011) carried out a study on Comparison of stability
criteria for concrete dams in different approximate methods based on finite element
analysis. The accuracy of the approximate methods of U.S. regulations (Army Corps
of Engineers, U.S. Bureau of Reclamation, and U.S. Federal Energy Regulatory
Commission regulations for gravity dams) and Finite element method were
determined and compared with each other. The finite element method was found more
accurate than the three U.S. regulatory methods and recommended specifically at the
level of the dam near the base, where the elasticity properties of the foundation were
very effective. Lotfi et.al. (2011) carried out a study on Application of H-W boundary
condition in dam-reservoir interaction problem. Dynamic analysis of unbounded
reservoir was studied. Hagstrom and Warburton ‘s non-reflecting boundary conditions
(NRBC) were used and harmonic response was calculated. The performance and
accuracy of NRBC was examined by comparing the results with exact solution. The
numerical results confirmed very good behavior of the NRBC in the frequencies
above the fundamental frequency of the reservoir but below this frequency the
boundary condition did not perform very well, especially when it was applied in close
distances from the dam.
Stability Analysis of Gravity Dams Using STAAD PRO” by T Subramani,
D.Ponnuvel [2] in June 2012. These papers present the stress analysis of gravity dams
is performed to determine the magnitude and distribution of stresses throughout the
structure for static and dynamic load conditions and to investigate the structural
adequacy of the substructure and foundation. The STAAD Pro provides the most
appropriate values to learn or investigate a constructed dam or pre constructed dam.
He says that the computations are very difficult to perform, due to coupling between

the uplift pressure and the cracking length.
A. Ghobarah and M. Ghaemianz [3] (1998) conducted an experimental study of a
small-scale model of a concrete gravity dam. Tests were carried out on a 1:100 model
monolith of the Pine Flat concrete gravity dam located on King's River near Fresno,
California. Tests have been conducted in order to simulate the hydrostatic,
hydrodynamic, and seismic loads. Dynamic loads have been estimated using a
simplified method of analysis in concrete gravity dams. The loading mechanism was
designed with two actuators to apply four concentrated loads at the upstream face of
the dam model The static load representing the hydrostatic pressure was constant. The
dynamic load was periodically applied by an actuator to represent the dynamic effects
of the earthquake loading. The construction of the dam model of plain concrete,
where the characteristics of the dam model were maintained with the same properties
as the prototype. The gravity load effect of the dam has been calculated analytically.
The results of experiments showed that it is possible to simulate the hydrodynamic
load on a dam model using a limited number of concentrated mechanical loads.
During the test of the model, Strains measuring with the same properties of the
material in the prototype are found to be in good agreement with strains which were
calculated using the finite element approach. The stresses at the upper part of the dam
model and the prototype of the same material properties are found to be in close
agreement.
Comparison of Design and Analysis of Concrete Gravity Dam” by Md. Hazrat Ali,
Md. Rabiul Alam [4] in 2011. In this paper mainly tells about the dam stability with
the different earthquake intensities, the increase of horizontal intensities the dam
stability will decrease. The finite element method is used for calculation. Sufficient
base width, adequate strong rock foundation, drainage gallery to reduce uplift
pressure, silt pressure, and construction Joints need to be ascertained to improve
factor of safety against sliding. Finally, it can be concluded that it would not be
feasible to construct a concrete gravity dam for kh values greater than 0.3 without
changing other loads and or dimension of the dam and keeping provision for drainage
gallery to reduce the uplift pressure significantly.
Analysis of Concrete Gravity Dam by 3D Solid Element Modeling using STAAD
Pro” by Jay p. Patel, R. Chhaya [5] in May 2015 In this paper, the 3D modeling and
analysis of gravity dam of solid elements using STAAD pro. The loads and the load

combinations are International Journal of Pure and Applied Mathematics Special
Issue 290 consider as per 6512. In this paper, directly analyzed the dam by solid
elements using STAAD Pro. There are some uncertainties still prevailing regarding
stability at support conditions. In this paper, Solid foundations are considered to avoid
this situation.
2.3 Conclusion
This chapter deals with numerous numbers of literature that have been found helpful
for carrying out of the work. The literature review provides the guidelines to carry out
analysis and design of the gravity dam along with its components analytically and
using softwares.

Chapter 3
HYDROLOGY AND HYDRAULIC ENGINEERING ASPECT
3.1 Rainfall Data for Region
Fig 3.1 & 3.2 Rainfall statistics of region

3.2. Calculation of Annual Inflow
Annual rainfall in the catchment area: 134.29cm (assume data based on 75%
reliability)
Using khosla’s formulae:
Yield Q= P-0.48T
Where Q= yield in cm
P=rainfall in cm
T= mean annual temperature = 25°C
Yield= 134.29-0.48*25
= 122.29cm
For catchment area of 4736.70km2
➢ Design catchment yield= 4736.70*106
*122.29*10-2
*10-6
= 5821.40Mm3
(annual inflow)
3.3. Calculation of Annual Outflow
➢ Water supplied to nearby thermal power station annually= 70Mm3
➢ Water supplied to population of 70,000 annually
(Assuming per capita water requirements as 135lpcd)
= 135*10-3
*70,000*365
= 3.44Mm3
(Let us take this value as 5Mm3
)
➢ Water released daily (as per agreement by various states and departments)
(Assuming daily release rate = 4,00,000m3
)
Therefore, water released annually = 4,00,000*365
= 146Mm3
(Take this value as 150Mm3
)
➢ Annual water requirements of crops
Considering water requirements of crop = 227.5cm
(120(rice) + 40(wheat) + 45 (vegetables) + fodder (22.5)

and Area to be irrigated= 67506ha
Water required for irrigation annually = 227.5*10-2
*67506*104
*10-6
= 1535 Mm3
(Considering whole rain water as runoff which will compensate
irrigation efficiencies)
Total outflow required annually = 70+1535+5+150
= 1760Mm3
(annual outflow)
➢ Required live storage= annual inflow-annual outflow
= 5821.40-1760
= 4061.40Mm3
➢ Required dead storage
Assume rate of silting= 4.90Mm3
/yr
Considering design life of project as 100 years
Therefore, Silt accumulated throughout design life= 4.90*100
= 490Mm3
Consider dead storage as 20% of live storage = 0.2*4061.40
= 812.28 Mm3
Dead storage will be maximum of above two values i.e., 812.28Mm3
Reservoir storage capacity= live storage+ dead storage
= 4061.40+812.28
= 4873.68 Mm3
Consider reservoir capacity as 4900Mm3
Area available at F.R.L = 186.80 Km2
Therefore, Height of dam = 4900/186.80
= 26.23m
(Assuming freeboard of 1.5m)
Total height of dam = 26.23+1.5
= 27.73m

3.4 Controlling Levels
➢ Proposed foundation R.L.=243.00m
➢ Top of Bridge: R.L. 270.73mm (243.00+27.73)
➢ Freeboard=1.5m (should be 3-4% of height of dam and should be
always greater than 1m)
➢ Full Reservoir Level: R.L. 269.23m
➢ High Flood Level: R.L. 266.33m
➢ Afflux R.L.: R.L. 267.33m
➢ Top of Approach Bund: R.L. 270.73m
3.5 Salient Features of Reservoir
➢ Catchment Area: 4736.70 m2
➢ Submerged Area: 1589.60 Ha
➢
Water Storage Capacity: 4900 Mm3
➢ Total Command Area:147274 Ha
➢ Total Benefited Area: 103825 Ha
➢ Irrigable Area: 67506 Ha
➢ Irrigation Capacity:18558 Ha

Chapter 4
ANALYSIS OF GRAVITY DAM
4.1 Elementary Profile of a Gravity Dam:
Fig 4.1- Elementary profile of Dam
1. Top width a=0
2. Free board =0
3. Therefore, H=H1.
Important points:
• Cross section of dam is right angled triangle. i.e shape of the dam is same as of
that hydrostatic pressure distribution diagram.
• Only 3 forces will act on the dam.
1. Self-weight (w)
2. Water pressure (P)
3. Uplift pressure (U)
Calculation:
1. Self-weight (w) = 0.5 *b*H*Sc

Where, Sc= Specific weight of concrete
Therefore, Self-weight = 0.5*29.5*26.23*24
= 9285.42 KN.
W = 928.5 tons.
2. Water pressure force = 0.5* Vw * H2
= 0.5* 9.81*26.232
= 3374.70 KN
P = 337.5 tons.
3. Uplift pressure force = 0.5* b* Vw*H *CU
Where, Cu = uplift pressure co efficient
= 1.2 (generally taken from 1.1 -1.2)
Therefore, U = 0.5*29.5*9.81*26.23*1.2
= 4554.50 KN.
Therefore, U = 455.5 ton.
Table 4.1 Moment about toe of elementary profile
Name of the force Magnitude (KN) Distance from toe.
(m)
Moment about toe
(KN m)
W 9285.42 19.67 182644.21
P 3374.70 9.24 31182.23
U 4554.50 19.67 89587.02
Here, P & U are overturning moments
& W causes resisting moments.
∑H = P
Therefore,
∑H = 3374.70 KN.
&
Therefore,
∑V = W – U
= 9825.42 – 4554.50
= 4730.92 KN.
Total Overturning Moments
Therefore,
Mo = 31182.23 + 89587.02
= 120769.25 KN m.

Therefore,
MR = 182644.21 KN m
Therefore,
Net Moment(∑M) = 61874.96 KN m.
=
61874.96
4730.92
X = 13.08 m.
• Eccentricity (e) =
𝑏
2
− 𝑋
(e) =
29.5
2
− 13.08
(e) = 1.67 m.
Base width of the elementary profile
It is determined by two criteria
• Stress criteria
• Stability or sliding criteria.
1. Stress criteria:
For no tension develop in reservoir full condition the resultant R must pass
through outer third point M2 as shown.
By taking moment about M2 & equating it to zero.
𝑝 ℎ
3
+
𝑢 𝑏
3
=
𝑤 𝑏
3
𝑤 ℎ2
2
∗
ℎ
3
+
1
2
∗ 𝑏 ∗ Cu ∗ ℎ ∗
𝑏
3
=
1
2
∗ 𝑏 ∗ ℎ ∗ Sc ∗
𝑏
3
Therefore, b =
ℎ
√𝑠−𝑐
Therefore, b =
26.23
√2.4−1.2
Therefore, b = 24 m
The design bed width will be greater than above value,
In our case b= 29.5 > 24 m
Hence, it is ok.
2. Stability or Sliding criteria:
For no sliding to occur
∑H= 0

P = µ (w-u)
𝑤 ℎ2
2
= µ(
1
2
∗ 𝑏 ∗ ℎ ∗ Sc −
1
2
∗ 𝑏 ∗ ℎ ∗ 𝑤)
Therefore, b =
ℎ
µ∗( 𝑠−𝑐)
b =
26.23
0.8∗( 2.4−1.2)
(co-efficient of friction = 0.8)
Therefore, b = 27.32 m.
The base of the dam should be greater at the two valves calculated above,
i.e.24 m & 27.32 m. (we have provided 29.5m)
In our case, it is almost equal to stability criteria and the tolerance evaluated is
only 0.5m.
4.2 Practical Profile of a Gravity Time:
• The elementary profile of a gravity dam (i.e. a triangle with maximum water
surface at apex) is only a theoretical profile
• Certain changes will have to be made in the profile in order to cater to the
practical needs. These needs are
1. Providing a straight top width, for road construction over the top of the
dam.
2. Providing a free board above the top water surface, so that water may not
spill over the top of the dam due to wave action, etc.
• As, the addition of these two provisions cause the resultant force to shift
toward the heel.
• As the Rf is shifting toward the heel so, tension will develop at the Toe.
• In order to avoid the development of the tension at the toe, we have to add
some concrete at the upstream side.
So, now profile can be checked for the stability analysis of the Gravity Dam
• It is not determined by comparing the height of the dam with limiting
condition of dam.
• If, Height of the dam is less than
H <
𝑓
Ɣw( Sc+1)
Then, Dam will be low gravity dam, otherwise it will be high gravity dam.
Where,
f = Permissible compressive stress of dam material.

Ɣw = unit weight of water.
Sc = specific gravity of dam material.
-
Fig 4.2 Practical Profile of Dam
• Freeboard calculation:
1. If, height of wave that is hw is given,
Freeboard = 1.5* hw.
2. If, height of wave is not given,
Freeboard = 4 – 5% of h.
• Top width of the Dam can from economical criteria as 14% of h
a = 14% of h
4.2.1 Design:
Let us assume compressive force acting on gravity dam be 120 t/m2
F =120 * 9.80665 = 1177 KN/m2
Step 1: freeboard
Say, 5% of depth of the water
Freeboard =
5
100
∗ 26.23
= 1.31 m.
Freeboard ≈ 1.5 m.
Step 2: Total Height of the Dam

H = h + freeboard
H = 26.23 + 1.5
H = 27.73m.
Step 3:
Ɣw = unit weight of water.
Ɣw = 9.81 KN/m2
H1 =
𝑓
Ɣw( Sc+1)
H1 =
1177
9.81( 2.4+1)
H1 = 35.28 m
H < H1,Hence, it is the low gravity dam.
Step 4:Top width can be taken from economic criteria, 14% of H
a =
14
100
∗ 27.73
a = 3.88 m.
a ≈ 4 m.
Step 5: Base width of elementary profile,
B =
ℎ
√(𝑆𝑐−𝑐)
B =
26.23
√2.4−1.2
B = 24 m.
now, upstream offset
=
𝑎
16
=
4
16
= 0.25 m.
Total Base width,
= upstream offset + base width of elementary profile
= 0.25 +24
= 24.25 m.
Step 6: Distance up to which upstream slope is vertical from upstream water
= 2a * √𝑆𝑐
= 2* 4 * √2.4
= 12.39 m.
Batter end at the depth below upstream water land
= 3.1* a* √𝑆𝑐

= 3.1* 4* √2.4
= 19.21 m.
Vertical Batter Height = 19.21 – 12.39
= 6.82 m.
Fig 4.3- Calculated practical profile Dam
4.3 Calculation of Forces Acting on the Dam and Stability Analysis of Dam
4.3.1 Forces Acting on Dam
Fig 4.4-Typical Section of Gravity Dam

• A gravity dam has been defined as a structure which is designed in such a way
that its own weight resists the external forces.
• The line of the upstream face of the dam is taken as the reference line and is
known as the Base line of the Dam or the Axis of the Dam.
4.3.1.1. Water Pressure Force
• It is major external force.
• Water Pressure varies linearly with the depth of water.
• The pressure diagram is triangular in shape.
• When the u/s face is vertical, intensity is zero at water surface and equal to
γwH at base.
a. On Upstream Side (P1)
Fig 4.5- Force on Upstream Side

Resultant Force = Area of the triangle formed by pressure diagram
= (1/2) * γwH2
= (1/2) * 9.81 * 26.232
= 3374.70 KN
Acts at a H/3= 8.74m from base of the dam. (center of gravity of triangle)
b. On downstream side (P2)
Fig 4.6- Force on Downstream Side
Resultant Force = Area of the triangle formed by pressure diagram
= (1/2) * γwH’2
= (1/2) * 9.81 * 5.42
= 143.03 KN
Acts at a H/3= 1.8m from base of the dam. (center of gravity of triangle)
If upstream face is vertical, hydrostatic pressure distribution diagram is triangle with
zero at the free surface and γwH at heel as per Pascal’s Law. According to Pascal’s

Law, Pressure (P) is given by , P = 𝜌gh = γwH
4.3.1.2. Uplift Pressure Force (Pu)
• Second Major External Force
• Water seeping through the pores, cracks and fissures in the
foundation and dam will exert uplift pressure on the base of the
dam.
• Uplift forces virtually reduces the downward weight of the dam and
hence acts against the stability.
a. Without Drainage Gallery
Fig 4.7- Uplift Pressure without Drainage Gallery
Uplift Pressure = Area of Trapezium
= (1/2) * (base of dam)* ( γwH * γwH’)
= 0.5 * 29.5 * (257.32 + 52.97)
= 4576.78 KN
Acts at a 11.51 m from axis of the dam. (Center of gravity of trapezoid)

b. With Drainage Gallery
Fig 4.8- Uplift Pressure with Drainage Gallery
The ordinate at x can be found as: -
x = γwH’+ (1/3) (γwH- γwH)
= 52.98 + (1/3) (9.81*26.63 – 9.81*5.4)
= 121.09 m
Now, Uplift Pressure Force = Area of Uplift Pressure Diagram
= Area of (Trapezium 1) + Area of (Trapezium)
∴Pu= 5.4/2 * (257.31+121.09) +24.1/2*(121.09+52.98)
∴Pu= 3119.22 KN or 311.92 ton
As we see the significant reduction in the value of Upload Pressure Force. As the
uplift force is decreased, the vertical forces are increased resulting in improving the
overall stability of gravity dam.

4.3.1.3. Self -Weight Force of Dam (W1 and W2)
• It is the most important force; stability of dam largely depends on
this force.
• For design purpose, only unit length of dam is considered.
• The resultant of all downward force is represented by total weight
of the dam acting at the centre of gravity of dam.
Self-Weight Force of dam = Volume of Dam * Unit Weight of dam material
= l * b* h * γwc
= (27.73 * 4*1*24) +(0.5*25.23*25.5*1*24)
= 10382.46 KN
Fig 4.9- Diagram for C.G. Calculation
The cross section is divided into rectangles, triangles, weight of each along with its
C.G are determined.
4.3.1.4. Silt Pressure Force (Ps)
The silt load carried by river water gets stored in the reservoir leading to one of the
major problems. i.e. reservoir sedimentation. The dam will be subjected to silt
pressure in addition to the water pressure.

Silt Pressure Intensity = γsub*Hs*ka
Where, γsub = submerged unit weight of water
Hs = height of silt deposit
ka = active earth pressure coefficient
Now, γsub =
γw(G+e)
1+𝑒
- γw
=
9.81∗(2.7+0.7)
1+0.7
– 9.81
= 9.81 KN/m2
If ka is not known we take it as, ka = 1/3 =0.33 and height of silt deposition of our
dam is 2.8m.
∴ Ps = (1/2) * γsub*Hs
2
*ka
= (1/2) * 9.81 * 2.82
*0.33
= 12.82 KN or 1.282 ton
Acts at
Hs
3
= 2.8/3 = 0.933m above the base of the dam.
According to USBR (United States Bureau of Investigation) and IS: 6512:1984
Maximum silt pressure = (360/2) * Hs
2
= 180*2.82
= 14.11kN > 12.82 Hence, it is OK.
4.3.1.5. Wave Pressure Force (Pw)
Waves are generated on the reservoir surface because of the wind blowing
over it. Wave pressure force depends on height of wave developed.
According to IS6572:1972
Height of wave, hw is given by following two equations.

i) hw = 0.032 √𝑉𝐹 + 0.763 – 0.271 F3/4
, if F<32 Km
ii) hw = 0.032√𝑉𝐹 , if F >32Km
where, V is the speed (in kmph) of the wind on location
F is the fetch distance over a straight of dam
At our dam location site,
F=30Km and V= 16Km/hr.
∴ hw = 0.032√16 ∗ 30 + 0.763 – 0.271 (30)3/4
=2.009 m
≅ 2.00 m
∴ Wave pressure Intensity = 2.4 * γw * hw
= 2.4*9.81*2
= 47.09 KN/m2
∴ Wave Pressure Force (Pw) =
1
2
∗
5ℎ𝑤
3
∗ 2.4 γwhw
= 2 γwhw2
= 2×9.81×22
= 78.48 KN or 7.848 tonn
Acts at (3/8) × hw = 0.75 m from free surface.
4.3.1.6. Weight of water at Tail Water Side (WT)
Water presents at inclined side of downstream side will also have weight affecting the
stability of dam.
∴ WT = (1/2) × 5.4 × 9.81
= 138.79 KN or 13.88 tons
Acts at 1.75m from toe of dam.

4.3.2. Nature of The Forces and Moments (With Respect to Toe)
Where, P1 = Upstream Water Pressure Force
P2 = Downstream Water Pressure Force
W1 = Weight of Rectangular portion of Dam
W2 = Weight of Triangular portion of Dam
Pu = Uplift Pressure Force
WT = Weight of water at the tail water side
Ps = Silt Pressure Force
Pw = Wave Pressure Force
Table 4.2 Force and moment w.r.t to toe
Name of the
Force
Magnitude
Of Force
(KN)
Distance
from toe (m)
Moment
about toe
(KN. m)
Nature of
Moment
Sign taken
P1 3374.70 8.74 29494.88 Overturning Negative
P2 143.03 1.8 257.45 Resisting Positive
W1 2662.08 27.5 73207.2 Resisting Positive
W2 7720.38 17 131246.46 Resisting Positive
PU 4576.78 18 82382.04 Overturning Negative
WT 138.79 1.75 242.88 Resisting Positive
Ps 12.82 0.93 11.92 Overturning Negative
Pw 78.48 26.98 2117.39 Overturning Negative

Here, P1, Pu, Ps and Pw are overturning moments.
And P2, W1, W2 and WT are resisting moments.
∴ ∑ H = P1- P2+Ps + Pw
= 3374.70 -143.03+12.82+78.48
= 3322.97 KN
∴ ∑V =W1 +W2 + WT – PU
= 2662.08+7720.38+138.79-4576.78
= 5944.47 KN
Total Overturning Moments (Mo) = -(29494.88+82382.04+11.92+2117.39)
= -114006.23 KN. M
Total Resisting Moments (MR) = 257.45+73207.2+131246.46+242.88
= 204953.99 KN. m
∴ Net Moment = MR+ Mo
∴ ∑M = 204953.99 – 114006.23
∴ ∑M = 90947.76 KN .m
Lever Arm about toe (x) =
∑𝑀
∑𝑉
=
90947.76
5944.47
= 14.54 m
Eccentricity, (e) =
𝑏
2
– x = 15 – 14.54 = 0.45 m
4.3.3 Stability Analysis of Gravity Dam
4.3.3.1 Modes of Failures
Failure is unacceptable for dams because not only it is financially costly, but people’s
lives are put at risk. Despite having the goal to avoid any type of failure,
unfortunately, it still may occur due to different reasons. The United States has seen
numerous incidents for different size dams where lives were sadly lost. By extending
our research and finding out how we can prevent this from occurring we may be able
to prevent these accidents from occurring in the future. However, to start this process

one must be familiar with the different failure types and look at related case scenarios,
which may help us with coming up with a solution through empirical observation.
Failure of gravity dam occurs due to overturning, sliding, tension and compression. A
gravity dam is designed in such a way that it resists all external forces acting on the
dam like water pressure, wind pressure, wave pressure, ice pressure, uplift pressure by
its own self-weight. Gravity dams are constructed from masonry or concrete.
However, concrete gravity dams are preferred these days and mostly constructed. The
advantage of gravity dam is that its structure is most durable and solid and requires
very less maintenance.
A gravity dam may fail in following modes:
1. Overturning of dam about the toe
2. Sliding – shear failure of gravity dam
3. Compression – by crushing of the gravity dam
4. Tension – by development of tensile forces which results in the crack in
gravity dam.
The horizontal forces such as water pressure, wave pressure, silt pressure which act
against the gravity dam causes overturning moments. To resist this, resisting moments
are generated by the self-weight of the dam. If the resultant of all the forces acting on
a dam at any of its sections, passes through toe, the dam will rotate and overturn about
the toe. When the net horizontal forces acting on gravity dam at the base exceeds the
frictional resistance (produced between body of the dam and foundation), The failure
occurs is known as sliding failure of gravity dam. Masonry and concrete are weak in
tension. Thus, masonry and concrete gravity dams are usually designed in such a way
that no tension is developed anywhere. If these dams are subjected to tensile stresses,
materials may develop tension cracks. Thus, the dam loses contact with the bottom
foundation due to this crack and becomes ineffective and fails. Hence, the effective
width B of the dam base will be reduced. This will increase Pmax at the toe. Hence, a
tension crack by itself does not fail the structure, but it leads to the failure of the
structure by producing excessive compressive stresses. A gravity dam may fail by the
failure of its material, i.e. the compressive stresses produced may exceed the
allowable stresses, and the dam material may get crushed.
4.3.3.2 Factor of Safety Against Modes of Failure
a. Sliding Criteria
Fa ctor of safety against sliding criteria ›1
∴ FOS = μ∑V/∑H

= 0.7*5944.47/3322.97
Hence, it is ok & safe.
b. Overturning criteria
Factor of safety against overturning › 1.5
∴ FOS = MR/MO
c. Compression or Crushing (Stresses at heel and toe)
Direct stress, σd=P/A=∑V/b
=5944.47/29.5
∴σd=201.5 KN/m2
(Compressive)
Bending Stress, σb=My/1 =∑V.e.σ/b2
=5944.47*0.45*6/29.52
∴σb= 18.44 KN/m2
∴σb is compressive at toe & tensile at heel of the dam.
Now, stresses at heel & toe
σheel=∑V/b(1-6e/b)
=5944.47/29.5(1-6*0.45/29.5)
∴σheel=183.06 KN/m2
σheel=∑V/b(1+6e/b)
=5944.47/29.5(1+6*0.45/29.5)
∴FOS = 1.25›1
∴FOS = 1.79›1.5

∴σheel=219.95 KN/m2
For safety of the gravity dam against compression σheel/σtoe<f
Where, f=permission compressive strength of concrete used.
For our dam, f=250*1.5=375 KN/m2
Here, σheel/σtoe=183.06/219.95<375 KN/m2
d. Tension criteria
For the dam to be safe against tension, there should be no tensile stresses
developed in dam.
For this (1), σd≥σb
∴ 201.5›18.44
∴Hence it is ok & safe.
(2) e ≤ b/d
∴ 0.45<29.5/6
∴ 0.45<4.91 m
∴ Hence it is ok & safe.
So, dam is checked against all modes of failure and found out to be safe and
correct.
4.3.4 Galleries in Gravity Dam
4.3.4.1. Introduction
Galleries are openings or passageways left in the dam body. They may be
provided parallel or normal to dam axis at various elevations The galleries are
interconnected by steeply sloping passages or by vertical shafts fitted with lifts. The
shape and size of the gallery depends on the size of the damned and the function
served. Galleries have to be left in the gravity dams during their construction. The size
of the galleries depends upon the purpose; they have to perform. The galleries may be
aligned both along the axis and across the axis of the dam. It may be cement concrete
or masonry dam, some water definitely seeps through the joints and pores of the dam.
Galleries intercept the seeping water and relieve the dam from interval stresses. All
the galleries are given some longitudinal slope and small channels along both the

edges of the galleries are formed. Seeping water through the dam section is collected
by the channels running along the galleries. Since channels have longitudinal slope,
the collected water in channels keeps on flowing automatically and is collected at
some central place from where it is discharged into the D/S side of the dam.
4.3.4.2. Necessity and Importance of Galleries
• For inspection of dam from inside.
• To reduce the uplift pressure beneath the dam, so that to improve the stability of
dam.
• To drain off seepage water through the body of the dam.
• It provides access to spillway gates.
• It helps in locating pumps, observation devices.
• To provide an access to observe and measure the behavior of the structure after its
completion by fixing thermocouples and examining development of cracks.
• To provide space for header and return pipes for post-construction grouting of
longitudinal joints of the dam. Also, to provide access for grouting the
construction joints which cannot be done from the face of the dam.
• To provide access to the interior of the mass comprising the dam with a view to
inspect the structure and study the structural behavior of the dam in post-
construction period.
• Galleries form a measure to reach each and every part of the dam.
• Galleries are used to carry out grouting of the dam or the foundations.
• Galleries are used to study the behavior of the dam after completion.
• To provide space for header and return pipes for post-construction grouting of
longitudinal joints of the dam. Also, to provide access for grouting the
construction joints which cannot be done from the face of the dam.
4.3.4.3. Classification of Galleries
There are 2 broad types that are provided in gravity dam. They are as follows: -
1. Foundation or Drainage Gallery
2. Inspection Gallery

1. Drainage Gallery
• It is provided near the rock foundations.
• It is made to drawn off the water which percolates through the foundations. It is
also helpful for drilling and grouting of the foundations.
• Size ranging 1.5m × 2.2m to 2m × 2.5m after completing foundation grouting
drainage holes are drilled to collect seepage water and then it is drained off by
galleries.
• A foundation gallery generally extends along the length of the dam near the rock
surface conforming in elevation to the transverse profile of the canyon; in plan it
is nearer and parallel to the axis of the dam.
• It is a supplementary drainage gallery located parallel to the crest at about 2/3rd of
the base width from upstream face and extending usually only through the deepest
portion of the dam.
• It serves for intercepting seepage from the water face and conducting it away from
the downstream face and drilling and draining the downstream portion of the
foundation.
2. Inspection Gallery
• These galleries are provided at various elevations and meter connected by vertical
shafts.
• Generally, these are the extension of foundation galleries and provision is made
alongside.
• These galleries serve inspection purpose providing dam interior for control of the
dam.
• It is a gallery to provide access to the interior of the mass comprising the dam with
a view to inspect the structure and study the structural behaviour of the dam in
post-construction period. It also caters for the drainage, gate and grouting galleries
also serve as inspection galleries. Bhakra dam has galleries aggregating in length
to 5 km.

4.3.4.4. Design Criteria
Galleries should be placed at about 5% to 7.5% of the dam height.
It should have minimum cover of 3m from upstream face of the dam.
For low gravity dam, the width is generally ranging from 1.5m to 2m and height
varies from 2 to 2.4/2.5m.
For length, it should cover all the length of dam with sufficient passageways. And
the drainage pipes are laid along the length of diameter varies from 4 to 6 inches.
All the corners should be rounded and have chamfer effect to cater effect of the
excessive stress causing by weight of the dam.
4.3.4.5. Provision of Galleries
• Height of the gallery from the base of the dam (left side) = 5-7% of H
= 1.5 m
• Height of the gallery from the base of the dam (right side) = 7.5 % of H
=2m
• Offset(cover) from the axis of dam = Top width(4m) + 1.4m
= 5.4m
• Size of the gallery Provided = 2.1 m×2.5m on both sides of each 80m length
• Size of the walkway and side drains
Width of Walkway =1.8m with 0.25 m above drain level.
Drains are laid on the both sides of walkway with 0.25 m depth and 0.15m width.
• Drain pipes = Should be placed at regular interval (generally 0.75m to 1m).

Now, all the drainage galleries, passageways should be connected well by any means
according to situation. In large gravity dams, for vertical access lifts are also provided
now days. Also shafts and stairs are generally use to inspect the dam. Dams are also
provided with shafts. Shaft is a vertical opening in the dam. Shafts connect galleries at
various levels. Shafts are generally provided with lifts so as to conduct effective
inspection of the dam and also to facilitate quick approach anywhere in the dam. They
are sometimes used to measure the deflections of the dam also.
Galleries can also be divides as the rectangular, oval or circular. The shape of the
gallery is decided as per the head engineer at the project site. Generally, rectangular
and oval shaped are constructed. The representation of this can be seen in following
figure below.
Fig. 4.10 Photo from inside of drainage gallery walkway

Fig 4.11. Types of galleries
Fig. 4.12 Provision of drainage gallery in our project

STABILITY ANALYSIS OF GRAVITY DAM FOR VARIOUS LOAD COMBINATION IN MS-
EXCEL:
DAM LOADING:
As per IS 6512-1984
1.0 External Water Pressure
2.0 Internal Water Pressure (Pore Water Pressure or Uplift)
3.0 SiltPressure
4.0 IcePressure
5.0 Earthquake Loads
6.0 Weight of structure
7.0 Forces from gates and other appurtenant structures
LOAD COMBINATIONS:
A Construction Condition: Dam Completed But no Water (U/S &D/S)
B Normal Operating Conditions: Full Reservoir and Normal Tail Water, With Normal Uplift
C Flood Discharge Conditions: Full Reservoir and Tail Water at Flood Elevation With
Normal Uplift
D Combination A + Earthquake
E Combination B + Earthquake
F Combination C, With Extreme Uplift (Drainage Inoperative)
G Combination E, With Extreme Uplift (Drainage Inoperative)

w1
a RWL cc
a b
1
1 CG (x,y)
TWL
2
h1
4.0 25.50
f d
X T = 29.500
b
0.99
0.55
0.0
DAM ANALYSIS BASED ON IS : 6512 - 1984 AND USBR
NON OVERFLOW SECTION
f d= 44.68 Degree
gc =
gw =
H =
a =
b =
cc =
m =
(KN/m2)
(KN/m2)
m
m
m H
m
0.70 -- from 0.5 to 0.75
Block
1
2
Area(m2)
110.9
321.7
x(m) y(m)
2.0 13.9
12.5 8.4
Coordinate of CG from U/S toe
x = 9.805 m
y= 9.81 m Y
Horizontal Seismic Coefficient (ah) =
Additional Wt. due gates etc = ''Wg' =
Bottom Width of Dam = (T) =
Elevation of Reservoir Level from Base of Dam 'Hu' =
Elevation of Tailwater Level from Base of Dam 'Hd' =
Maximum Tailwater Level During Flood 'Hdm' =
Maximum Silt level in reservoir 'Hslt' =
gshlt
Effect. Unit Wt of Silt for Vertical Pressure (gvslt) =
Unit Cohesion at Base (Coh) =
Reservoir Water Pressure (Pu) = (gw.Hu
2/2) =
Tail Water Pressure (Pd) = (gw.Hd
2/2) =
Weight of Dam Section = (Wd) =
KN
29.50 m
m
m During Normal Operation
m During Flood Discharge Conditions
m
(KN/m2)
(KN/m2)
3374.7 KN
-143.0 KN
10385.7 KN
Wave Pressure Force= 77.0 KN
Load of water wedge on dam at D/S =Wwd =
at x2 =
y2 =
144.6 KN --Assumed that '(H-cc)' >h1
27.7 m
3.6 m
Addl Horizontal Press due to Silt at U/S Side (Pslt) =
at x4 =
y4 =
12.6 KN
1.9 m
0.9 m
Uplift Force (Wu) =
Inertia Force Due to Earthquake on Weight of Dam :
Vertical Force, Vev =
Horizontal Force, VeH =
4490.0 KN
-3808.1 KN
3427.3 KN
26.2
5.4
15.0
2.8
3.208
9.810
83.00
24.00
9.81
27.73
1.50
4.00
2.50

Total Vert. Load (Wv)=(Wg+Wd+Wwu+Wwd+Wu+Vev+Wslt) =
Total Horizontal Load (WH ) = (Pu+Pd + VeH + Pslt) =
2232.2 KN
3321.2 KN
Moment Computation : About Toe Sign Convention:
Moment due to 'Wd' (Md) =
Moment due to Addl wt. of Gates (Mg) =
204548.5 KN-m +ve --> restoring moment
0.0 KN-m -ve --> overturning moment
Moment due to Wwd, Mwd =
Moment due to Water Pressure at U/S, Mpu =
Moment due to Water Pressure at D/S, Mpd =
Moment due to Uplift, Mu =
263.2 KN-m
-29506.2 KN-m
257.5 KN-m
-80820.7 KN-m
Moment due to Silt Pressure at U/S Side, Mhslt =
Moment due to Wave Pressure at U/S Side, Mp =
Moment due to Earthquake Forces (Me) =
-11.7 KN-m
2077 KN-m
125411 KN-m
Total Restoring Moment about toe of dam (MR) =
Total Overturning Moment about toe of dam (Mo) =
205069.1 KN-m
110338.6 KN-m
Calculation of Factor of Safety
1. Factor of Safety Against Overturning :
= MR/Mo = 1.86 FOS > 1.2, Structure is Safe Against Overturning
2. Sliding :
Without Considering the Shear Strength, Factor of Safety Against Sliding:
FS = m.Wv / WH =
With Shear Strength, Shear Friction Factor :
SFF =[m.Wv/Ff + T.Coh/Fc] / WH =
Calculation of Stresses :
0.47
0.70
< 1.0, Structure is Unsafe Against Sliding
< 1.0, Structure is Unsafe Against Sliding
Distance of Point of action of Resultant from Toe = M / V =
Distance of Point of action of Resultant from Centre of Base 'ec' =
15.20 m
0.45 m
Compressive Stress at Toe, pn1 = (V/T)*(1+6.ec/T) =
Compressive Stress at Heel, p = (V/T)*(1- 6.ec/T) =
n2
82.6 KN/m
68.7 KN/m
=
=
0.83 N/mm2
0.69 N/mm2
Principal stress atToe of Dam, s1 = pn1.Sec2b = 20.2 KN/m = 0.20 N/mm2
Principal stress at Heel of Dam, s2 = 20.2 KN/m = 0.20 N/mm2
[s2 = pn2.Sec2a - gw.H.tan2a]
Shear Stress at Toe t1 = pn1 .Tanb = 0.0 KN/m = 0.00 N/mm2
Shear Stress at Heel t2 = -(pn2 - gw.H).tana 272.0 KN/m = 2.72 N/mm2
LOAD COMBINATIONS :
A Construction Condition : Dam Completed But no Water (U/S &D/S)
B Normal Operating Conditions : Full Reservoir and Normal Tail Water, With Normal Uplift
C Flood Discharge Conditions : Full Reservoir and Tail Water at Flood Elevation With Normal Uplift
D Combination A + Earthquake
E Combination B + Earthquake
F Combination C, With Extreme Uplift (Drainage Inoperative)
G Combination E, With Extreme Uplift (Drainage Inoperative)
Tail Water Pressure During Flood (Pdm) =
Moment due to Tail Water During Flood (Mdm) =
Load of water wedge on dam at D/S during Flood=Wwdm =
Moment due to Wwdm, Mwdm =
at x2m =
y2m =
1103.6 KN
5518.1 KN
1115.9 KN
24.4 m
10.0 m
5641.6 KN-m

DESCRIPTION LOAD 'A' LOAD 'B' LOAD 'C' LOAD 'D' LOAD 'E' LOAD 'F'
Total Vert. Load (Wv) 10385.7 6040.3 10178.6 10385.7 4154.8 6734.9
(KN)
Total Hor. Load (WH ) 0.0 3244.2 2283.7 3427.3 6957.6 2283.7
(KN)
Restoring Moment (MR) 204548.5 205069.1 215708.2 205069.1 205069.1 205069.1
KN-m
Overturning Moment(MO) 0.0 110338.6 110338.6 125411.0 108261.4 102083.9
KN-m
Factor of Safety Against O 2.0E+09 1.9 2.0 1.6 1.9 2.0
>1.5, OK >1.5, OK >1.5, OK >1.5, OK >1.5, OK >1.5, OK
Factor of Safety Against S 7.3E+07 1.3E+00 3.1E+00 2.12 0.42 2.1E+00
>2.0, OK >2.0, OK >2, OK >2.0, OK < 2, Revise >1.2, OK
Factor of Safety Against S 5.5E+07 1.1E+00 1.6E+00 1.61 0.38 1.7E+00
> 1.0, OK > 1.0, OK > 1.0, OK > 1.0, OK < 1, Revise > 1.0, OK
Dist.of Pt. of action of Res 19.70 15.68 10.35 7.67 23.3 15.29
m m m m m m
Dist.of Pt. of action of Res -4.9 -0.9 4.4 7.08 -8.6 -0.5
m m m m m m
Compressive Stress at To -2.0 165.9 653.7 859.02 -104.09 203.2
< 7000, OK < 7000, OK < 7000, OK < 7000, OK < 7000, OK < 7000, OK
Compressive Stress at He 706.2 243.6 36.4 -154.90 385.8 253.4
< 7000, OK < 7000, OK < 7000, OK < 7000, OK < 7000, OK < 7000, OK
Principal stress atToe of D -4.1 335.5 1322.0 1737.25 -210.5 410.9
<7000,OK < 7000 OK < 7000 OK < 7000, OK < 7000, OK < 7000 OK
Principal stress at Heel of 706.2 243.6 36.4 -154.90 385.8 253.4
< 7000, OK < 7000, OK < 7000, OK < 7000, OK < 7000, OK < 7000, OK
Shear Stress at Toe (Kn/ -2.1 167.7 660.9 868.57 -105.2 205.4
Shear Stress at Heel (Kn/ 706.2 243.6 36.4 -154.90 385.8 253.4

w1
53.0
1 CG (x,y)
TWL
2
h1
4.0 25.51
f d
X T = 29.50
gw.[Hd+(Hu-Hd)/3] =
0.0
U X =
Y =
gw.Hd=
Without Drainage Gallery
Calculation of Uplift Forces :
f d= 44.68 Degre
gc =
gw =
H =
a =
b =
cc =
24.00 KN/m3
9.81 KN/m3
27.73 m
1.50 m
4.00 m
2.50 m
Block Area(m2) x(m) y(m)
1 110.9
2 321.8
2.0 13.9
12.5 8.4
Y
gw.Hu = 257
Bottom Width of Dam = (T) =
Elevation of Reservoir Level from Base of Dam 'Hu' =
Elevation of Tailwater Level from Base of Dam 'Hd' =
Maximum Tailwater Level During Flood 'Hdm1' =
Uplift Pressure at U/s (Upu) = (gw.Hu) =
Uplift Pressure at D/s (Upd) = (gw.Hd) =
29.50 m
26.2 m
5.4 m
15.0 m During Flood Discharge Conditions
257.3 KN
53.0 KN
Uplift Pre. at Face of Drainage Gallery (As per USBR Recommendations) :
Upg = gw.[Hd+(Hu-Hd)/3] = 121.1 KN
However, There is no Drainage Gallery
Total Uplift Force (U) =
Uplift Moment (Mu) at Toe =
-4576.8 KN
82326.6 KN-m
Uplift Pressure at D/s during Flood (Udm) = (gw.Hdm) = 147.15 KN
Uplift Pre. at Face of Drainage Gallery During Flood Conditions :
Upgm = gw.[Hd+(Hu-Hdm)/3] = 89.7 KN
During Normal Discharge
With Drains Drains Choaked
During Flood Discharge
With Drains Drains Choaked
Total Uplift
Force (KN)
-2567.4
(Und)
-4576.8
(Undc)
-1323.0
(Ufd)
-3795.4
(Ufdc)
Total Uplift
Moment at
-42809.1
(Mund)
-82326.6
(Mundc)
-74643.2
(Mufd)
-74643.2
(Mufdc)
Toe (KN-m)

w
w
A. Hydrodynamic Effects due to Resorvior (U/S):
Pe =Cs.ah.gw.Hu Where,
Pe = Hydrodynamic pressure due to earthquake
Cs = A dimensionless cofficient which varies with shape and dept
ah = Design Horizontal Seismic Coefficient
gw = Unit weight of water
Hu = Reservoir Depth
Cs = Cm/2{z+z0.5} z = y{2-y/h)/h
Cm = Maximum value of Cs as per Fig. 10 of IS : 1893 - 1984
For y=h, Cs = Cm = 0.000
'qu' = 90.00 Degree y = Depth below surface
Cm = 0.000
ah = 0.55
h = 26.23 m
g = 9.81 KN3
Peu = 0.00 KN2
Hydrodynamic Forces :
Total Hydrodynamic Pressure Vhu = 0.726 . Peu .hu = 0.0 KN
Total Hydrodynamic Moment Mhu = 0.299 . Peu . hu2 = 0.0 KN-m
Forces Due to Horizontal Earthquake Accelaration :
Base Shear (Vbu) =0.6* ah.Wd = 3427.3 KN
Base Moment (Mbu) =0.9. ah.Wd.Y = 50409.9 KN-m
Forces Due to Vertical Earthquake Accelaration :
Vertical Force = 2/3.ah.Wd. = 3808.1 KN
Moment about Toe of Dam = 75001.1 KN-m
B. Hydrodynamic Effects due to Tailwater :
'qd' = 42.60 Degree
Cm = 0.387
ah = 0.55
h = 5.40 m
g = 9.81 KN3
Ped= 555.62 KN2
Hydrodynamic Forces :
Total Hydrodynamic Pressure Vhd = 0.726 . Ped .hd = 2178.2 KN
Total Hydrodynamic Moment Mhu = 0.299 . Ped . hd2 = 4844.3 KN-m
C. Total Forces Due to Earthquake :
Horizontal Base Shear at U/S = 3427.3 KN
Vertical Force = -3808.1 KN
Total Moment about Toe of Dam (Me) = 125411.0 KN-m

4.4 Analysis of Dam in Staad Pro
4.4.1 About the Software
STAAD or (STAAD Pro) is a structural analysis and design software
application originally developed by Research Engineers International in 1997.
STAAD Pro is one of the most widely used structural analysis and design software
products worldwide. It supports over 90 international steel, concrete, timber &
aluminum design codes. It can make use of various forms of analysis from the
traditional static analysis to more recent analysis methods like p-delta analysis,
geometric non-linear analysis, Pushover analysis (Static-Nonlinear Analysis) or a
buckling analysis. It can also make use of various forms of dynamic analysis methods
from time history analysis to response spectrum analysis. The response spectrum
analysis feature is supported for both user defined spectra as well as a number of
international code specified spectra. Additionally, STAAD Pro is interoperable with
applications such as RAM Connection, Auto PIPE, SACS and many more
engineering design and analysis applications to further improve collaboration between
the different disciplines involved in a project. STAAD can be used for analysis and
design of all types of structural projects from plants, buildings, and bridges to towers,
tunnels, metro stations, water/wastewater treatment plants and more.
4.4.2 Analysis Using Finite Element Method
Finite element models are used for linear elastic static and dynamic analyses and for
nonlinear analyses that account for interaction of the dam and foundation. The finite
element method provides the capability of modeling complex geometries and wide
variations in material properties. The stresses at corners, around openings, and in
tension zones can be approximated with a finite element model. It can model concrete
thermal behavior and couple thermal stresses with other loads. An important
advantage of this method is that complicated foundations involving various materials,
weak joint son seams, and fracturing can be readily modelled. Special purpose
computer programs designed specifically for analysis of concrete gravity dams are
CG-DAMS (Anatech1993), which performs static, dynamic, and nonlinear analyses
and includes a smeared crack model, and MERLIN (Saouma 1994), which includes a
discrete cracking fracture mechanics model.
Two-dimensional, finite element analysis is generally appropriate for concrete gravity
dams. The designer should be aware that actual structure response is three dimensions
a land should review the analytical and realistic results to assure that the two-
dimension approximation is acceptable and realistic.

4.4.3 Procedure Adopted for Analysis
Step - 1: Creation of nodal points based on the positioning of plan.
Node points are entered into the STAAD file to get desired geometry.
Step - 2: Representation of plates.
By using add plate command we can draw the plates between the
corresponding node points. After creating one section we can apply
transitional repeat command to get whole dam structure.
Step - 3: 3D view of structure.
Select 3D render view option from view menu to get the 3D view of structure.
Step - 4: Supports and property assigning.
After the creation of structure, apply supports at the base of structure as fixed
supports. In addition, to this assign property to materials and cross sections
asper IS 456:2000 and SP 16:2000
Step - 5: Assigning of dead loads.
Dead loads can be assigned to section of dam by adopting following
procedure:
Modeling > load & definition > add-dead load > self-weight.
Step -6: Assigning of load combinations.
Assign different load combinations A, B, C, D, E, F or G as per IS 18262 in
order to analyze dam for most critical load condition.
Step-7: Save and run the file.
Check for errors and eliminate every error. Finally select post processing
mode & take print out of required functions (B.M, S.F., displacement etc.)
required for analysis.
Step-8: Design of footing.
After analysis of gravity dam Foundation v8i can be used to design foundation
based upon our requirements e.g. types of foundation, depth of footing etc.

4.4.4 System Analysis
A low concrete gravity is analyzed here using STAAD PRO software.
For simplification in analysis the batter in upstream side of dam is neglected i.e.
upstream section is assumed as straight. Dam has total height of 27.73m, base width
of 29.5m etc. Other important dimensions are shown in diagram below along with
assumed profile for analysis.
STAAD Input

Table 4.3. Node Points

Table 4.4. plate thickness, Materials and supports

Table 4.5. Combination of load Cases
Dam section:
Fig 4.13: Dam section

Fig 4.14. 3D rendered View

Fig 4.15. Construction condition and Normal Operation condition

Fig4.16. Flood Discharge representation

Fig 4.17. Combination earthquake forces representation

Fig 4.18. Extreme Uplift force representation

STAAD OUTPUT
Load combination A:

Fig 4.19. Load Combination A
Load combination B:

Fig.4.20. Load Combination B

Load combination C:

Fig 4.21. Load Combination C
Load combination D:

Fig 4.22 Load combination D
Load combination E:

Fig 4.23. Load Combination E

Load combination F:

Fig 4.24. Load combination F
Load combination G:

Fig 4.25. Load combination G

Chapter 5
DESIGN OF COMPONENTS OF GRAVITY DAM
5.1 Design of Spillway
“Spillways are structures constructed to provide safe release of flood waters from a
dam to a downstream area”.
5.1.1 Types of Spillways –
There are different types of spillways that can be provided depending on the
suitability of site and other parameters. Generally, a spillway consists of a control
structure, a conveyance channel and a terminal structure, but the former two may be
combined in the same for certain types. The more common types are briefly described
below:
1. Drop Spillway
2. Ogee Spillway
3. Siphon Spillway
4. Chute or Trough Spillway
5. Shaft Spillway
6. Side Channel Spillway
5.1.1.1 Ogee Spillway
The Ogee spillway is generally provided in rigid dams and forms a part of the main
dam itself if sufficient length is available. The crest of the spillway is shaped to
conform to the lower nappe of a water sheet flowing over an aerated sharp crested
weir.
It is a modified form of drop spillway. Here, the downstream profile of the spillway is
made to coincide with the shape of the lower nappe of the free falling water jet from a
sharp crested weir.
In this case, the shape of the lower nappe is similar to a projectile and hence
downstream surface of the ogee spillway will follow the parabolic path where “0” is
the origin of the parabola.
The downstream face of the spillway forms a concave curve from a point “T” and
meets with the downstream floor. This point “T” is known as point of tangency. Thus

the spillway takes the shape of the letter “S” (i.e. elongated form). Hence, this
spillway is termed as ogee spillway.
The shape of the lower nappe is not same for all the head of water above the crest of
the weir. It differs with the head of water. But for the design of the ogee spillway the
maximum head is considered.
If the spillway runs with the maximum head, then the overflowing water just follows
the curved profile of the spillway and there is no gap between the water and the
spillway surface and the discharge is maximum.
When the actual head becomes more than the designed head, the lower nappe does not
follow the ogee profile and gets separated from the spillway surface.
Thus a negative pressure develops at the point of separation. Due to the negative
pressure, air bubbles are formed within the flowing water. These air bubbles air
responsible for the frictional force (i.e. abrasion) which causes much damage to the
spillway surface.
Again, if the head of water is less than the designed head, the waterjet adheres to the
body of the spillway and creases positive pressure which reduces the discharge
through the spillway.
Fig 5.1- Spillway of Dam

5.1.1.2 Design of Ogee Spillway Profile
Fig 5.2- Ogee Spillway
As the spillway look like a high weir the Cd is assume as 2.2,
𝑄 = 𝐶𝑑 × 𝐿𝑒 × 𝐻𝑒
3
2
1600 = 2.2 × 𝐿𝑒 × 𝐻𝑒
3
2
Let us first work out the approximate value of He, for a value of effective length
Le=L= clear waterway= 23×8=184 m
1600=2.2 × 184 × 𝐻𝑒
3
2
𝐻𝑒= 2.50 m
The height of the spillway above the river bed P= 261.33-238= 23.33 m.
Since,
𝑃
𝐻𝑒
i.e
23.33
2.5
=9.332 m >1.33 ok
It is a high spillway; the effect of velocity head can therefore be neglected.
𝑃+𝐻𝑒
𝐻𝑒
=
23.33+2.5
2.5
=10.332 > 1.7 ok

The discharge coefficient is not affected by fail water conditions and the spillway
remain high spillway.
5.1.2.1 Up Stream Slope:
The upstream face of the dam and spillway is proposed to be kept vertical, however a
batter of 1:10 will be provided from stability consideration in the lower part.
Effective length of the spillway (Le) can be work out as
𝐿𝑒 = 𝐿 − 2(𝑁𝐾𝑝 + 𝐾𝑎)𝐻𝑒
Assuming that 90°
cut water nose peirs and rounded abutment shall be provided. we
have,
𝐾𝑝 = 0.01 and 𝐾𝑎 = 0.10 , no. Of pier =22
Also, assuming that actual value of the He is slightly more than the approximate value
worked out say, let it be 4 m.
we have,
𝐿𝑒 = 184 − 2(22 × 0.01 + 0.10) × 4
=181.44 m
Hence,
𝑄 = 𝐶𝑑 × 𝐿𝑒 × 𝐻𝑒
3
2
1600 = 2.2 × 181.44 × 𝐻𝑒
3
2
𝑯𝒆= 2.523 m
Which can be taken to 2.5 m. The crest profile will be designed for
𝑯𝒅= 2.5 m (neglecting velocity head)
5.1.2.2 Velocity of Approach:
𝑉
𝑎 =
1600
(181.44 + 22 × 2.44) + (23.33 + 4)
= 𝟎. 𝟐𝟒𝟗 𝒎
𝒔
⁄

𝐻𝑎= velocity head =
𝑉𝑎
2
2×𝑔
= 0.00316 m,
This is very small and therefore neglected.
5.1.8.2.3 Downstream Profile:
The downstream profile for vertical upstream face is given by equation,
𝑋1.85
= 2 × 𝐻𝑑
0.85
𝑌
𝑌 =
𝑋1.85
2 × 𝐻𝑑
0.85 = 𝑌 =
𝑋1.85
2 × 2.50.85
𝑌 =
𝑋1.85
4.3579
Before we determine the various coordinate of the downstream side profile, we shall
first determine the tangent point.
The downstream side slope of the dam is given toe 0.7 H: 1 V.
Hence,
𝑑𝑦
𝑑𝑥
=
1
0.7
Differentiated the eqn
of the downstream side profile w.r.t. to x, we get,
𝑑𝑦
𝑑𝑥
=
18.5 𝑋(1.85−1)
4.3579
=
1
0.7
𝑋0.85
=
4.3579
1.85×0.7
X=4.17 m
The coordinate from X=0 to X= 4.17m.
5.1.2.4 Upstream Side Profile:
The upstream side profile may be design as per giver equation,
𝑌 =
0.724(𝑋 + 0.27𝐻𝑑)1.85
𝐻𝑑
0.85 + 0.126𝐻𝑑 − 0.4315𝐻𝑑
0.375
(𝑋 + 0.27𝐻𝑑)0.625
Using 𝐻𝑑 = 2.5 𝑚

𝑌 = 0.332(𝑋 + 0.675)1.85
+ 0.315 − 0.6084(𝑋 + 0.675)0.625
This curve should go up to X= -0.27𝐻𝑑
X=-0.27×4 = -0.675 m.
5.1.2.5 Practical Profile Of Ogee Spillway:
Fig 5.3- Practical Profile of Ogee Spillway
-0.197222201
-0.123519682
-0.073970742
-0.039508973
0
-0.063652761
-0.229468322
-0.485838099
-0.827233725
-1.250005016
-1.751447246
-2.329424408
-2.98217911
-3.220879234
-3.5
-3
-2.5
-2
-1.5
-1
-0.5
0
-1 0 1 2 3 4 5
Series1 Series2

Design of Kawlewada Dam and its Components.

Design of Kawlewada Dam and its Components.

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