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    1.INTRODUCTION

    A concrete dam is a solid structure, made of concrete , constructed across a river to create a

    reservoir on its upstream. The section of the concrete dam is approximately triangular in shape,

    with its apex at its top and maximum width at bottom. The section is so proportioned that it

    resists the various forces acting on it by its own weight. Most of the gravity dams are solid, so

    that no bending stress is introduced at any point. The gravity dams are usually provided with an

    overflow spillway in some portion of its length. The dam thus consists of two sections; namely,

    the non-overflow section and the overflow section or spillway section. The design of these two

    sections is done separately because the loading conditions are different. The overflow section is

    usually provided with spillway gates. The ratio of the base width to height of most of the gravity

    dam is less than 1.0. The upstream face is vertical or slightly inclined. The slope of the

    downstream face usually varies between 0.7: 1 to 0.8: 1.

    In this research paper the concrete section of rampad sagar dam or periayr dam has taken

    into consideration. The stability of the dam has determined by varying the slopes of upstream

    and downstream section.

    2. LITERATURE REVIEW ON ANALYSIS OF STABILITY OF DAMS:

    2.1.ROMAN DAMS:

    The need to store water, in particular in dry areas, was probably the main reason for the

    construction of the first dams, which consisted of earth structures built in 3000 B.C., in Jawa,

    present Jordan, the highest being 4m high and having a length of 80m (Figure 1a). These are

    considered to be the oldest known dams. In that time romans use hyadraulic lime,earth and rock

    to construct the dams. Those dams lasted for 60 to 80 years. Also around the 2nd century, the

    Proserpina dam was built (Figure 1d) (H=22m, L=426m), close to Mrida. The characteristics of

    the dam presents a group of nine buttresses, close to the upstream face, which support the thrust

    of the downstream slope, in case the reservoir needs to be emptied. The dam maintains its

    original function, which is to supply water to the city of Mrida (Jansen1980). In the 18th and

    19th centuries, the economic development and a favorable legal framework for the management

    of water resources led to the construction of new dams. Nevertheless, the prevailing structural

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    scheme was based on trapezoidal cross-sections with a large volume, following the Roman

    tradition, despite the tendency for reduction of cross sections (La 1993).

    In 1971 spain scientist Sazily gave some new directions to dam design.

    According to Sazilly, the cross-section of the dam should be designed so as to avoid the failure

    by excessive compressive stress and by sliding. Both scenarios should be observed at the contact

    between the dam and foundation, but also along the body of the dam. Also according to Sazilly,

    the sliding scenario had never been observed in any previous failure, so design of the cross-

    section should just take into account only the first criterion, while the sliding scenario should be

    verified afterwards. In accordance with Sazillys reference, the proposed stress analysis was

    based on M. Mrys work6, about the stability of arches, which was disclosed by M. Blanger in

    the Cours de Mcanique Applique (Course of Applied Mechanics) delivered at Lcole

    Nationale des Ponts et Chausses (National School of Bridges and Roads), France. Another

    fundamental contribution was given by S. Rankine in 1872, with the publication of an article in

    The Engineer, with the title Report on the design and construction of masonry dams. In this

    article, Rankine confirms the validity of the former works by Sazillys and Delocres (Wegmann

    1899). The sole difference consists of the use of different limit stress values for extreme load

    cases. Since the limit stress is a vertical stress, the use of a lower limit stress for the downstream

    face is proposed, because the larger angle with the vertical leads to a higher principal stress when

    compared with the upstream face. Since no mathematical formulation was used for defining

    these limits, just by taking into account the observation of existing works, Rankine suggested the

    limit of 9.8kg/cm (0.96MPa), for upstream, and 7.6kg/cm (0.75MPa), for downstream (Rankine

    1881).

    2.2.DEVELOPMENTS IN 20th

    CENTURY:

    In 1905 special reference must be made to G. Wisners and E. Wheelers contributions, who, by

    request of the Reclamation Service, initiated studies to better understand the load distribution on

    arch dams. Global stability analysis remains an indispensable component in the safety evaluation

    of gravity dams, considering the possibility of various sliding mechanisms, which place along

    the foundation surface or involve rock joints (e.g. Rocha 1978). The accident of the Malpasset

    arch dam in 1957 stressed the importance of the hydro-mechanical behavior of rock foundations

    (Londe 1987). Knowledge on issues such as the effectiveness of the grout curtain and drainage

    systems progressed with extensive field monitoring (Casagrande 1961). These data provide the

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    means to validate and calibrate numerical models of seepage problems, which were already

    developed in the early days (Serafim 1968). For stability analysis of gravity dams, the diagram of

    uplift water pressure along the sliding surface is a decisive factor. In the absence of drainage, a

    triangular or trapezoidal diagram needs to be considered . When drains are present, a reduction

    of the water pressure can be considered at the drain location, leading to a bilinear diagram. It is a

    common design assumption to adopt a reduction factor of 2/3 (Leclerc, Lger, and Tinawi 2003).

    However, the possible development of upstream cracking may allow the full reservoir pressure

    along the crack. Current design codes provide the rules for these analyses and a comparison of

    criteria of three American regulatory agencies may be found in Ebeling et al. (2000), while the

    practice in various countries is discussed in Ruggeri (2004)

    3.TYPES OF CONCRETE DAM:

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    The basic shape of a concrete gravity dam is triangular in section (Figure 1a), with the top crest

    often widened to provide a roadway (Figure 1b).

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    Various forces acting on the dams are shown in the below figure:-

    Figure 2

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    4.BASIC DEFINITIONS:

    1. Axis of the dam: The axis of the gravity dam is the line of the upstream edge of the top (or

    crown) of the dam. If the upstream face of the dam is vertical, the axis of the dam coincides with

    the plan of the upstream edge. In plan, the axis of the dam indicates the horizontal trace of the

    upstream edge of the top of the dam. The axis of the dam in plan is also called the base line of

    the dam. The axis of the dam in plan is usually straight. However, in some special cases, it may

    be slightly curved upstream, or it may consist of a combination of slightly curved RIGHT

    portions at ends and a central ABUTMENT straight portion to take the best advantages of the

    topography of the site.

    2. Length of the dam: The length of the dam is the distance from one abutment to the other,

    measured along the axis of the dam at the level of the top of the dam. It is the usual practice to

    mark the distance from the left abutment to the right abutment. The left abutment is one which is

    to the left of the person moving along with the current of water.

    3. Structural height of the dam: The structural height of the dam is the difference in elevations of

    the top of the dam and the lowest point in the excavated foundation. It, however, does not

    include the depth of special geological features of foundations such as narrow fault zones below

    the foundation. In general, the height of the dam means its structural height.

    4. Maximum base width of the dam: The maximum base width of the dam is the maximum

    horizontal distance between the heel and the toe of the maximum section of the dam in the

    middle of the valley.

    5. Toe and Heel: The toe of the dam is the downstream edge of the base, and the heel is the

    upstream edge of the base. When a person moves along with water current, his toe comes first

    and heel comes later.

    6. Hydraulic height of the dam: The hydraulic height of the dam is equal to the difference in

    elevations of the highest controlled water surface on the upstream of the dam (i. e. FRL) and the

    lowest point in the river bed.

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    Figure 3

    5.FORCES ACTING ON GRAVITY DAM

    A gravity dam is subjected to the following main forces:

    1. Weight of the dam

    2. Water pressure

    3. Uplift pressure

    4. Wave pressure

    5. Earth and Silt pressure

    6. Ice pressure

    7. Wind pressure

    8. Earthquake forces

    9. Thermal loads.

    These forces fall into two categories as

    a) Forces, such as weight of the dam and water pressure, which are directly calculable from the

    unit weights of the materials and properties of fluid pressures; and

    b) Forces, such as uplift, earthquake loads, silt pressure and ice pressure, which can only be

    assumed on the basis of assumption of varying degree of reliability. It is in the estimating of the

    second category of the forces that special care has to be taken and reliance placed on available

    data, experience, and judgment. It is convenient to compute all the forces per unit length of the

    dam.

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    5.1. WEIGHT OF THE DAM

    The weight of the dam is the main stabilizing force in a gravity dam. The dead load to be

    considered comprises the weight of the concrete or masonry or both plus the weight of such

    appurtenances as piers, gates and bridges. The weight of the dam per unit length is equal to the

    product of the area of cross-section of the dam and the specific weight (or unit weight) of the

    material. The unit weight of concrete and masonry varies considerably depending upon the

    various materials that go to make them. It is essential to make certain that the assumed unit

    weight for concrete/masonry or both can be obtained with the available aggregates/ stones. The

    specific weight of the concrete is usually taken as 24 kN/m3, and that of masonry as 23 kN/m3 in

    preliminary designs. However, for the final design, the specific weight is determined from the

    actual tests on the specimens of materials. It is essential that the actual specific weight of

    concrete during the construction of the dam should not be less than that considered in the final

    design. Attempts should be made to achieve the maximum possible specific weight. The factors

    governing the specific weight of the concrete are water-cement ratio, compaction of concrete and

    the unit weight of the aggregates. For high specific weight, the aggregates used should be heavy.

    For convenience, the cross-section of the dam is divided into simple geometrical shapes, such as

    rectangles and triangles, for the computation of weights. The areas and controids of these shapes

    can be easily determined. Thus the weight components W1, W2, W3 etc. can be found along

    with their lines of action. The total weight W of the dam acts at the C.G. of its section.

    5.2. RESERVOIR AND TAILWATER LOADS (WATER PRESSURE):

    The water pressure acts on the upstream and downstream faces of the dam. The water pressure

    on the upstream face is the main destabilizing (or overturning) force acting on a gravity dam.

    The tail water pressure helps in the stability. The tail water pressure is generally small in

    comparison to the water pressure on the upstream face. Although the weight of water varies

    slightly with temperature, the variation is usually ignored. In case of low overflow dams, the

    dynamic effect of the velocity of approach may be significant and will deserve consideration.

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    The mass of the water flowing over the top of the spillway is not considered in the analysis since

    the water usually approaches spouting velocity and exerts little pressure on the spillway crest.

    (Figure 4. showing various weights of dam section acting downwards)

    If gates or other control features are used on the crest they are treated as part of the dam so far as

    application of water pressure is concerned. The mass of water is taken as 1000 kg/m3. Linear

    distribution of the static water pressure acting normal to the face of the dam is assumed. Tail-

    water pressure adjusted for any retrogression should be taken at full value for non-overflow

    sections and at a reduced value for overflow sections depending on the type of energy dissipation

    arrangement adopted and anticipated water surface profile downstream. The full value of

    corresponding tail-water should, however, be used in the case of uplift. The water pressure

    intensity p (kN/m2) varies linearly with the depth of the water measured below the free surface y

    (m) and is expressed as:

    p=w* hwhere w is the specific weight of water (= 9.81 kN/m3 for w =1000 kg/m 3). For simplification,

    the specific weight of water may be taken as 10 kN/m3

    instead of 9.81 kN/m3. The water

    pressure always acts normal to the surface. While computing the forces due to water pressure on

    inclined surface, it is convenient to determine the components of the forces in the horizontal and

    vertical directions instead of the total force on the inclined surface directly.

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    (a) U/s face vertical:

    When the upstream face of the dam is vertical, the water pressure diagram is triangular in shape

    with a pressure intensity of wh at the base, where h is the depth of water. Th e total water

    pressure Per unit length is horizontal and is given by:

    It acts horizontally at a height of h/3 above the base of the dam.

    (b) U/s face inclined:

    When the upstream face ABC is either inclined or partly vertical and partly inclined, the force

    due to water pressure can be calculated in terms of the horizontal component PH and the vertical

    component PV. The horizontal component is given as earlier and acts horizontal at a height of

    (h/3) above the base. The vertical component PV of water pressure per unit length is equal to the

    weight of the water in the prism ABCD per unit length. For convenience, the weight of water is

    found in two parts PV1 and PV2 by dividing the trapezium ABCD into a rectangle BCDE and a

    triangle ABE.

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    Thus the vertical component PV= PV1 + PV2 = weight of water in BCDE + weight of water in

    ABE. The lines of action of PV1 and PV2 will pass through the respective centroids of the

    rectangle and triangle.

    5.3. UPLIFT PRESSURE:

    Water has a tendency to seep through the pores and fissures of the foundation material. It also

    seeps through the joints between the body of the dam and its foundation at the base, and through

    the pores of the material in the body of the dam. The seeping water exerts pressure and must be

    accounted for in the stability calculations. The uplift pressure is defined as the upward pressure

    of water as it flows or seeps through the body of the dam or its foundation. A portion of the

    weight of the dam will be supported on the upward pressure of water; hence net foundation

    reaction due to vertical force will reduce. The area over which the uplift pressure acts has been a

    question of investigation from the early part of this century. One school of thought recommends

    that a value one-third to two-thirds of the area should be considered as effective over which the

    uplift acts. The second school of thought, recommend that the effective area may be taken

    approximately equal to the total area. The code of Indian Standards recommends that the total

    area should be considered as effective to account for uplift.

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    Figure 5

    According to the Indian Standard (IS :6512-1984), there are two constituent elements in uplift

    pressure: the area factor or the percentage of area on which uplift acts and the intensity factor or

    the ratio which the actual intensity of uplift pressure bears to the intensity gradient extending

    from head water to tail water at various points. Effective downstream drainage, whether natural

    or artificial, will generally limit the uplift at the toe of the dam to tail water pressure. Formed

    drains in the body of the dam and drainage holes drilled subsequent to grouting in the

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    foundation, where maintained in good repair, are effective in giving a partial relief to the uplift

    pressure intensities under and in the body of the dam. The degree of effectiveness of the system

    will depend upon the character of the foundation and the dependability of the effective

    maintenance of the drainage system. In any case, observation of the behaviour of the dam will

    indicate the uplift pressures actually acting on the structure and when the lift pressure are seen to

    approach or exceed design pressures, prompt remedial measures should necessarily be taken to

    reduce the uplift pressures to values below the design pressures.

    This following criteria are recommended by IS code for the calculating uplift forces :

    (a) Uplift pressure distribution in the body of the dam shall be assumed, in case of both

    preliminary and final designs, to have an intensity which at the line at the formed drains exceeds

    the tailwater pressure by one-third the differential between reservoir level and tail-water level.

    The pressure gradient shall then be extending linearly to heads corresponding to reservoir level

    and tailwater level. The uplift shall be assumed to act over 100 percent of the area.

    (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 tailwater pressure by one-third the differential between the reservoir

    and tailwater heads. The pressure gradient shall then be extended linearly to heads corresponding

    to reservoir level and tailwater level. The uplift shall be assumed to act over 100 % area. For

    final designs, the uplift criteria in case of dams founded on compact and unfissured 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 % of the area.

    5.4. EARTH AND SILT PRESSURES:

    Gravity dams are subjected to earth pressures on the downstream and upstream faces where the

    foundation trench is to he backfilled. Except in the abutment sections in specific cases and in the

    junctions of the dam with an earth or rockfill embankment, earth pressures have usually a minor

    effect on the stability of the structure and may be ignored. The present procedure is to treat silt as

    a saturated cohesionless soil having full uplift and whose value of internal friction is not

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    materially changed on account of submergence. Experiments indicate that silt pressure and water

    pressure exist together in a submerged fill and that the silt pressure on the dam is reduced in the

    proportion that the weight of the fill is reduced by submergence. IS code recommends that a)

    Horizontal silt and water pressure is assumed to be equivalent to that of a fluid with a mass of

    1360 kg/m3, and b) Vertical silt and water pressure is determined as if silt and water together

    have a density of 1925 kg/m3.

    Figure 6

    5.5. ICE PRESSURE:

    The problem of ice pressure in the design of dam is not encountered in India except, perhaps, in a

    few localities. Ice expands and contracts with changes in temperature. In a reservoir completely

    frozen over, a drop in the air temperature or in the level of the reservoir water may cause the

    opening up of cracks which subsequently fill with water and freezed solid. When the next rise in

    temperature occurs, the ice expands and, if restrained, it exerts pressure on the dam. In some

    cases the ice exerts pressure on the dam when the water level rises. For ice sheets of wide extent

    this pressure is moderate but in smaller ice sheets the pressure may be of the same order of

    magnitude as in the case of extreme temperature variation. Ice is plastic and flows under

    sustained pressure. The duration of rise in temperature is, therefore, as important as the

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    magnitude of the rise in temperature in the determination of the pressure exerted by ice on the

    dam. Wind drag also contributes to the pressure exerted by ice to some extent. Wind drag is

    dependent on the size and shape of the exposed area, the roughness of the surface area and the

    direction of wind. Existing design information on ice pressure is inadequate and somewhat

    approximate. Good analytical procedures exist for computing ice pressures, but the accuracy of

    results is dependent upon certain physical data which have not

    been adequately determined. These data should come from field and laboratory. Till specific

    reliable procedures become available for the assessment of ice pressure it may be provided for at

    the rate of 250 kPa applied to the face of dam over the anticipated area of contact of ice with the

    face of dam.

    5.6. WIND PRESSURE

    Wind pressure does exist but is seldom a significant factor in the design of a dam. Wind loads

    may, therefore, be ignored.

    5.7. WAVE PRESSURE

    In addition to the static water loads the upper portions of dams are subject to the impact of

    waves. Wave pressure against massive dams of appreciable height is usually of little

    consequence. The force and dimensions of waves depend mainly on the extent and configuration

    of the water surface, the velocity of wind and the depth of reservoir water. The height of wave is

    generally more important in the determination of the free board requirements of dams to prevent

    overtopping by wave splash. An empirical method based upon research studies on specific cases

    has been recommended by T. Saville for computation of wave height hw (m). It takes into

    account the effect of the shape of reservoir and also wind velocity over water surface rather than

    on land by applying necessary correction. It gives the value of different wave heights and the

    percentage of waves exceeding these heights so that design wave height for required exceedance

    can be selected. Wind velocity of 120 km/h over water in case of normal pool condition and of

    80 km/h over water in case of maximum reservoir condition should generally be assumed for

    calculation of wave height if meteorological data is not available. When maximum wind velocity

    is known, the same shall be used for full reservoir level (FRL) condition and 2/3 times that for

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    MWL condition. The maximum unit pressure pw in kPa occurs at 0.125 hw, above the still water

    level and is given by the equation:

    Pw=24 hw

    The total wave force Pw, (in kN) is given by the area of the triangle 1-2-3

    Pw=20

    Figure 7

    5.8. EARTHQUAKE FORCES

    The earthquake sets up primary, secondary, Raleigh and Love waves in the earth's crust. The

    waves impart accelerations to the foundations under the dam and. causes its movement. In order

    to avoid rupture, the dam must also move along with it. This acceleration introduces an inertia

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    force in the body of dam and sets up stresses initially in lower layers and gradually in the whole

    body of the dam. Earthquakes cause random motion of ground which can be resolved in any

    three mutually perpendicular directions. This motion causes the structure to vibrate. The

    vibration intensity of ground expected at any location depends upon the magnitude of

    earthquake, the depth of focus, distance from the epicentre and the strata on which the structure

    stands. The predominant direction of vibration is horizontal. The response of the structure to the

    ground vibration is a function of the nature of foundation soil; materials, form, size and mode of

    construction of the structure; and the duration and the intensity of ground motion. IS:1893 - 1984

    code specifies design seismic coefficient for structures standing on soils or rocks which will not

    settle or slide due to loss of strength during vibrations. The seismic coefficients recommended in

    this standard are based on design practice conventionally followed and performance of structures

    in past earthquakes. In the case of structures designed for horizontal seismic force only, it shall

    be considered to act in any one direction at a time. The vertical seismic coefficient shall be

    considered in the case of structures in which stability is a criterion of design. For the purpose of

    determining the seismic forces, the country is classified into five zones.

    6.RAMPAD SAGAR DAM ON POLAVARAM PROJECT:

    Godavari is the largest river in South India, it starts at Nasik in the western ghats and runs South

    East area is about 1.2 lakh sq.miles, greater than the area of Britan. Its annual average flow is

    3600 Thousand Million Cubic ft. (TMC ) (83 MA ft.). But its highest yield is 5,860 TMC and the

    lowest in 65 years is 960 TMC. Its peak flood flow is more than 20 lakh cusecs. Godavari water

    is used by construction of an anicut near Rajahmundry during 1850-60 by Sir Arthur Cotton. The

    second crop depends upon low summer flows and hence higher food production required new

    irrigation projects and hence Rampada Sagar was conceived during the British rule to augment

    irrigation land. This project consists of a 428 ft. height dam , 20 miles upstream of Rajahmundry

    and 1.5 miles above Polavaram with two major canals, one extending on the left upto

    Visakhapatnam and the other on the right extending upto Gundlakamma river with a hydro

    power of 150 MW on the right bank.

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    ( Figure 8 Delta section of Godavari river)

    The dam is 6600ft. long and 428 ft. high from deepest foundation. FRL of the Reservoir

    is +198ft, with a water spread of 527 sq.miles with a gross storage of 690 TMC. Crest level of

    drum is +180ft. road level 237.82, Tail water is at +43ft. Foundation bed level rock is between

    bed width at foundation is 303 ft. under spillway section. To dispose of the maximum floods the

    spill way is 4,200 ft. long with 16 drum gates of 135ft. x 18ft. There will be 100 sluices of 10ft. x

    20ft with silt at +83 ft. to dispose of silt- laden floods. The river flow from the middle of June to

    middle of September will be diverted into the canals and the sand sluices will dispose of the

    floods at the diversion level of +145. The annual silt deposition is estimated at 2 TMC in the

    initial stages and 0.33 TMC during the later periods and hence the silt capacity is provided for168 TMC for a life of 400years for the reservoir.

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    (Figure 9 View of rampad sagar dam)

    7.SEISMIC RISKS TO POLAVARAM DAM

    Risks due to location in a highly earthquake prone rift zone of Bhadrachalam:

    Polavaram dam and its reservoir are located close to highly earthquake prone areas like

    Bhadrachalam which has been rated seismically as one of the 10 dangerous rift zones and it has

    faced hazardous earthquakes for some time. Koyna reservoir located under similar earthquake

    danger zone has experienced major earthquakes due to Reservoir Induced Seismicity [RIS] and

    experienced cracks in the dam resulting in serious damage in 1967. The higher the height of the

    dam, greater will be the damage due to earthquakes in the rift zones

    The Godavari river valley is within the NW-SE trending faults. These faults still show moderate

    seismicity occasionally. The Godavari graben area is in seismic Zone III of the seismic zoning

    map of Bureau of Indian Standard. In this zone an earthquake of magnitude 6 or intensity VIII

    may be expected. The earthquake of magnitude 5.7 was measured at Bhadrachalam in 1969. In

    terms of the risks of an earthquake with damage potential, the most active zones in A.P State

    are the Eastern Ghat belt and the Godavari valley. The minor risk areas are Hyderabad,

    Vinukonda-Ongole, Chittoor and Vizianagaram . Since 1800, a total of 80 earthquakes of

    magnitude 3.5 to 5.7 have struck different parts of the Andhra Pradesh State. The strongest of

    them was the April 1969 Bhadrachalam earthquake, which measured 5.7 on the Richter scale.

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    The earthquakes are known to be triggered by reservoir loading in area of moderate seismicity.

    However, magnitude of the triggered earthquake, is not anticipated to exceed the magnitude of

    the largest earthquake expected in the area. In the present case, earthquake may be triggered after

    reservoir loading and the largest expected earthquake in the area will be in the magnitude of 6. If

    this magnitude exceeds, then the peak ground accelerations may cause damage to the dams

    ( Figure 10 section view of rampad sagar dam)

    During 1850s Sir Arthor Cotton suggested for a barrage at Polavaram:

    Sir Arthor Cotton was a great humanist and a friend of the farmers wanted maximum utilization

    of Godavari waters for augmenting agriculture and suggested that in order to irrigate the uplands

    of East and West Godavari districts. Another anicut must be constructed on the upstream side of

    Rajahmundry. Because he was a great Irrigation Engineer with humanistic outlook and great

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    vision he knew that it will be a highly dangerous to propose a major water storage dam in the

    close proximity of growing townships like Rajahmundry which may be adversely affected due to

    collapse of such a major storage dam for one reason or the other. Hence Sir Arthor Cotton

    suggested for an anicut to irrigate more lands in the upland areas of Eastern ghats in East

    Godavari and West Godavari districts.

    In 1945, Madras Government proposed a high concrete dam at Polavaram site : Madras

    Presidency Government proposed a major reservoir project across Godavari before independence

    and it was known as Ramapada Sagar project with a height of 198ft. in the first phase to raised to

    208ft. in the final phase with a storage capacity of 690 TMC. This was proposed as a concrete

    dam with a total height of 438ft. upto the foundations with sand bed extending for a depth of

    about 230ft. below the bed level. The spillway was provided for a length of 4200ft for a peak

    discharge of 21 lakh cusecs. Since concrete dam had to be taken upto the bedrock for its safety

    the cost of the project became too high and hence the high cost factor made the dam not all

    feasible and hence it was given up.

    In 1953 Khosla Technical Committee suggested for a Barrage at Polavaram site: The

    Government of India appointed a high power technological committee under the chairmanship of

    Dr.A.N.Khosla, Chairman of the Central Water Commission (CWC) to study and submit report

    on the optimal utilization of water in Krishna-Godavari and Pennar rivers. This committee stated

    that there is a possibility of diverting Godavari water by constructing either a dam or a diversion

    barrage with a canal to transfer 142 TMC into Krishna river. The Committee further stated that if

    Ramapad Sagar dam is not built but a storage reservoir is constructed upstream on Godavari or

    its tributaries and only a diversion barrage is built at Ramapadsagar dam site the transfer of 142

    TMC of water into Krishna river will remain unaffected.

    In 1961 AP State Government Suggested for a Barrage at Polavaram site: In a technical report by

    the AP State Government prepared a 1961 on the optimum economic utilization of Krishna and

    Godavari waters the state Government recommended for construction of a barrage at Rampad

    Sagar site and a dam at Inchampalli to divert Godavari waters into Krishna rivers in Para 23 of

    the Report in the following words.

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    The only practical scheme for diversion of Godavari waters to Krishna basin the lower reaches

    is by construction of Inchampalli dam and Rampad Sagar barrage. By this it will be possible to

    divert waters at less cost than the previous proposals (made by Maharashtra state Government) as

    the tunnels are eliminated and length of the canal reduced. But this itself is very costly as

    commented upon by the technical committee (Khosla committee) who stated that with a small

    quantity of water for diversion the economics of the proposal becomes problematic.

    In 1962 the Technical Committee headed by Gulhati suggested for a barrage at Polavaram site:

    The Ministry of Irrigation and Power, Government of India appointed in a technical commission

    in May 1961 to study and submit a report on the utilization of Krishna and Godavari waters

    including the feasibility of diverting Godavari waters into Krishna river and the committee

    submitted its report in August 1962. This Commission was headed by an eminent engineer

    Mr.Gulhati along with other highly technically qualified experts as members. The Commission

    in its report stated that there will be ample surplus water in the upper part of the Godavari basin

    to meet the demands of thelocal projects and the surplus water from the lower part of the

    Godavari basin including the sub basins of Pranahita, Indravati and Sabari can be used for

    irrigation and hydro-power projects will be more than 10 MAF (435 TMC) and this surplus flow

    can be diverted into Krishna basin by the following 2 link canals.

    1. A link canal from the Godavari from the anicut at Albaka (or Singareddi) to Pulichintala on

    the Krishna river, estimated at Rs.40 crores. This link canal can transfer about 95 TMC (2.2

    MAF) to the Krishna.

    2. A link canal from Godavari near Polavaram can transfer about 211 TMC (4.8 MAF) into

    Krishna river at Vijayawada estimated at Rs.40 crores about 30 TMC from Penganaga can be

    transferred through a link canal to make up the shortage of water in the Upper Godavari area.

    In 1965 a technical Committee headed by Mr.A.C. Mitra suggested a barrage at Polavaram site:

    The Government of India appointed an expert committee in the wake of recurring floods in

    Godavari and Krishna rivers which were causing excessive flooding of the Kolleru lake to study

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    the impacts of floods and suggest remedial measures. This technical committee headed by an

    eminent irrigation expert Mr.A.C.Mitra along with other irrigation experts recommended for the

    construction of a barrage at Polavaram for irrigating the upland areas on either side of the

    barrage.

    Rampad Sagar Reservoir is so named for the reason that the waters of the reservoir will lap the

    feet of Srirama at the Bhadrachalam temple, 74 miles above the proposed dam near Polavaram

    village. This Concrete Dam was intended to irrigate 24 lakhs of acres with Paddy cultivation in

    addition to stabilizing irrigation in 21 lakh acres in Godavari and Krishna delta and will yield a

    million tonnes of rice that will eliminate all the pre-war imports of rice from Burma and

    Travancore. Hydro-power of 75000KV and the projected was expected to be completed by the

    end of 1946. Project cost was Rs.63 crores. The net return is 3.7% per annum on the net capital

    outlay. Rock was below 200 ft. and it proved uneconomical and posed difficulties and was given

    up.

    In 1970 AP State Engineers proposed a big reservoir at Polavaram but designated it as a barrage

    : AP State submitted Polavaram barrage scheme in June 1970 to the Bachawat Tribunal. This

    scheme consists of a barrage across Godavari at Polavaram with FRL at +145ft. and minimum

    pond level at +45ft with Left Bank Canal upto Vizag Port with Full Supply Level with (FSL) at

    +137ft and Right Canal upto Krishna river with FSLat +138ft. Safe Concrete Dam was replaced

    by a risky Earth-cum-rock fill dam

    In 1978 AP State Engineers proposed a hazardous earth-cum-rockfill dam at Polavaram site:

    AP state changed the Polavaram barrage scheme into an earth-cum-rockfill dam with a

    maximum height of 48.77m (160ft) with a crest length of 1555m (5100ft) . It had 2 spillways on

    the right flank sadal with 50 radial gates (50ft. x 42ft) with a flood lift of a 14ft. for peak design

    flood of 36 lakh cusecs. It had a concrete gravity dam on the left flank with Power house and

    river sluices. The earth dam is 35.05m (115ft) above the average river bed and 48.77m (160ft)

    above the deepest bed level of the river. This height for the dam is stated to be necessary for

    diverting the required quantity of water into the canals which proposed to irrigate vast areas on

    both the flanks. The MDDL and FRL stated to be required are +44.2m (145ft.) and RL +47.72m

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    (+150ft) respectively with gross storage capacity of 5665 Mm3 (192 TMC) The storage available

    between the minimum draw down level and FRL (44.20m to 45.72) is only 800 Mm3 (28.31

    TMC). The project serves 4.82 lakh ha. (11.90 lakh acres) of Ayacut during Kharif (June to

    October) and 2.27 lakh ha (5.6 lakh acres) under second crop (Jan to April) in the ultimate stage.

    The left canal, 208kmlong upto Visakhapatnam and it serves industrial needs and irrigates 1.89

    lakh ha under first crop and 1.25 lakh ha. under second crop in East Godavari and

    Visakhapatnam. A lift irrigation canal starts at Km 177 near Anakapalli, 130km long irrigates

    1.15lakh ha in Visakhapatnam and Srikakulam. Another lift canal, 177km long starts at

    Polavaram to serve upland areas of 0.57 lakh ha under first crop and 0.2 lakh ha under second

    crop in East Godavari and Visakhapatnam districts. The right main gravity canal 176km long

    upto Budameru river irrigates 1.21 lakh ha. under first crop and 0.80 lakh ha. under second crop

    in West Godavari and Krishna districts.

    In August, 1978 AP State made a conditional Agreement with Karnataka on Polavaram dam: On

    4-8-1978 an agreement was signed between Karnataka and AP State under which clause-VII

    states that under the condition that clearance to Polavaram project is given by CWC for

    FRL/MWL of +150ft. MSL. AP State agrees to divert 80 TMC into Krishna for utilization by

    projects upstream of Nagarjuna Sagar by allotting share of 45 TMC to AP State and 35 TMC to

    both Karnataka and Maharashtra. Another condition is that AP Sate submits Polavaram project to

    CWC within 3 months of striking an agreement with all the 5 river basin states and that AP state

    will bear the full cost of this water diversion and if this quantity diverted is exceeded the water

    will be shared in the above stated proportion. Surprisingly while the Karnataka state Government

    which has no adverse impacts due to Polavaram project has taken the initiative to fix the height

    of the Polavaram dam the most effected states of Madhya Pradesh and Orissa were left with the

    option of deciding to agree on the crucial matter on submersion of lands in their states. Andhra

    Pradesh made agreements with Madhya Pradesh on 7-8-1978 and Orissa on 15-12-1978 on the

    issue of submersion of lands due to Polavaram project with the condition that including

    backwater effect. The design of the Polavaram project should be such that the submersion should

    not exceed +150ft MSL at Konta in Madhya Pradesh and Motu in Orissa due to maximum

    Probable Flood and backwater effects determination in consultation with Central Water

    Commission.

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    July, 1979: CWC finds fault with AP State for a faulty agreement on Polavaram: The CWC sent

    letter No.6/125/78-T.E/25 12-2514, dated the 3rd July, 1979 to Andhra Pradesh Government, the

    material portion of which is as follows:-

    It is seen from the project report that the State Government of Andhra Pradesh have proposed

    the Polavaram project for an FRL/MWL of +150ft. Therefore, prima facie, with MWL at

    Polavaram at RL +150ft. submergence due to all effects including that of backwater effect will

    always be more than RL+150ft upstream and also at Konta. The State Government will no doubt

    be working out the backwater effects at Konta/Motu considering advance releases from

    polavaram dam. It is however seen that during the year 1966 CWC had observed that a flood

    level at Konta had reached an RL 46.595m (RL 152.88ft) which is 0.875m higher than RL

    45.72m (RL+150ft) This is an observed flood whose frequency is expected to be high. For a

    flood at Konta corresponding to frequency the flood adopted for the Polavaram dam (which will

    be between 1 in 500 years to 1 in 1000 years), the natural flood level at Konta should be

    expected to be substantially higher than RL +45.72m (RL +150ft) It would thus be seen that the

    stipulation that a flood level at Konta/Motu should not rise above RL +150ft will not be

    practicable and that the agreements entered into by the states may have to be suitably modified.

    Perhaps this situation about observed flood level at Konta might not have been known to you and

    other states when this agreement was concluded.

    In October 1979 Maharashtra supports the conditional agreement on Polavaram dam: On 15-

    10-79 the Maharashtra state Government took a very cantankerous cold blooded and brutal stand

    on the Polavaram dam project by demanding the Bachawat Tribunal to consider the agreement of

    4th August 1978 between AP state and Karnataka as a practicable one and to consider the

    temporary submergence in Orissa and Madhya Pradesh preventable by constructing and

    maintaining protective embankment in the interests of Justice and for securing most equitable

    allocation of waters in the Godavari river. Consequently Maharashtra wanted the tribunal to

    incorporate and give effect to clause VII in Karnataka Government in its report under Sec 5(2)

    and pass the required order and thereby implying that the tribunal must permit for the

    construction of Polavaram dam with FRL at +150ft irrespective of any disastrous consequences

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    and at any cost. Madhya Pradesh disagrees with the contention of Maharashtra:

    This Maharashtra petition was circulated to other basin states for replies. Karnataka did not file

    any reply. Andhra Pradesh submitted the tabulated statement of backwater level for the pre and

    post project conditions for 30 lakhs and 36 lakhs cusecs flood. AP wanted FRL 150subject to the

    safeguards regarding flood protection works. Madhya Pradesh disagreed with views of

    Maharashtra.

    Orissa insists on integrated water resources planning for projects at Inchampalli and Polavaram:

    Orissa stated that Polavaram and Inchampalli projects are closely interlinked because Polavaram

    project is dependent on the releases from Inchampalli Hydro-Power plant and the FRL and MWL

    of Polavaram depend upon the FRL and MWL of Inchampalli project and its spillway discharge

    capacity and the pattern of releases from Inchampalli and both these projects would be so

    palnned that the submergence in Madhya Pradesh and Orissa would not exceed +150ft due to all

    causes. Orissa rejected the arguments of Maharashtra on Polavaram project while Karanakata

    though did not file a reply yet it tried to support the arguments of Maharashtra.

    The raise in elevation of the surface profile of a river when the flow is retarder above a dam is

    referred to as the backwater effect of the dam. It is the excess submergence over and above that

    by natural floods as caused by the backwater effects due to the Polavaram dam that is to be

    avoided or minimized as far as possible. But the correct backwater effect or backwater level due

    to Polavaram dam must be determined by the CWC as per para 110 of the Bachawat Tribunal

    report.

    The tribunal under chapter-2 of the final report dt.7-7-1980 under sec 5 (3) and Paragraph 12 the

    tribunal left the matter for the clearance of the Polavaram project to the CWC after making the

    following observations

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    The CWC will naturally keep all these points in view while clearing the Polavaram project in

    consultation with the concerned parties, after giving due consideration to achieve the objectives

    mentioned in the project reports of Andhra Pradesh. The tribunal however, on its part does not

    find any difficulty for clearing the Polavaram project at FRL/MWL +150ft.

    AP State Proposes Embankments to Prevent submersion in Upper States and insists on

    conditions:

    On 26-10-1979 AP state agreed to prevent temporary submersion due to the dam by constructing

    and maintaining protective embankments. The AP also stated that there can be no question of

    diversion of Godavari waters into Krishna unless Polavaram project is cleared for FRL +150ft

    and subject to such safeguards as the tribunal may provide so as to give effect to all the

    agreements without detriment to any of the parties (Para 123 of the Tribunal report)

    1980: During the President rule in Orissa, a middle level engineer was deputed on behalf of

    Orissa state government to sign on agreement along with AP and Madhya Pradesh and Central

    government on Polavaram project. The Government of India gave in writing on 26-3-1980 that

    Polavaram dam with FRL at +150ft. is technically feasible. But Environmental safety was

    ignored

    In the final submissions before the Bachawat Tribunal the AP State Government demanded on

    25-2-1980 the tribunal that since both the upper states have agreed for permanent submersion of

    their lands upto +150ft the tribunal may permit submersion of lands in Orissa and Madhya

    Pradesh upto 175ft but it is not accepted because submersion had to be prevented by construction

    of embankments as suggested by the Central Water Commission with adequate pumping

    arrangements and drainage sluices. Thus the interstate agreement envisaged that AP state will

    submit proposals for Polavaram dam within 3 months of the agreement made by all the 5 river

    basin states so that the CWC will clear the project as expeditiously as possible to enable the state

    Government to complete the project in time .Because of the Delay of the project by 25 years, all

    the legal and environmental hurdles have cropped up such as increase of peak floods from 36 to

    50 lakhs cusecs and the consequential increase in submersion levels in upper states, making

    Bachawat Award conditions invalid. In fact, the villages likely to be submerged rose from 275

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    estimated in 1980 to 340 by 2010.This additional submersion of lands and villages is not

    acceptable to the Orissa and chattisgarh states and it amounts to violation of conditions of the

    Bachawat Tribuna of April.1980.

    30-4-1983: Dr.K.L.Rao warned that Polavaram dam is under-designed and is unworkable. He

    expressed strong opposition to the Dam because of various reasons like under-designed spillway

    for the higher levels of peak floods expected to occur in the near future.

    1985 : Detailed project report [DPR]of Polavaram project completed

    1987 : Project Report [DPR]submitted to the CWC

    1996 : R&R reports prepared through Centre for Evaluation of Socio-Economic Studies.These

    study reports were never updated on the basis of upgrading peak flood from 36 lakhs cusecs in

    1980 to50 lakhs cusecs in 2006 by A.P.state Engineers and also the Central water Commission

    without the consent of Orissa and Chattisgarh states as per the conditions of the Bachawat

    tribunal Award

    1996 :Dr.K.Sriramakrishnayya, irrigation Advisor to A.P.state Government strongly opposed

    polavaram dam for several reasons and suggested that it should be left to be decided by the

    future generations]for details see his report presented in brief elsewhere under these web sites on

    polavaram dam]

    June, 1999: Dam Break Analysis report for Polavaram by National Institute of Hydrology,

    Roorkee, a wing of Union Ministry of Water Resources at the request of the Environmental

    Protection Training and Research Institution (EPTRI) of the AP State Government which was

    interested with the preparation of environmental impact assessment report for Polavaram dam

    project.

    2002 : EIA-EMP reports prepared by the Environment Protection Training &Research

    Institute[EPTRI],Hyderabad are incomplete as they were based on old and incomplete data of

    1996

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    16-09-2005 : The AP State Government was in a great hurry to start construction work on

    Polavaram dam and since EPTRI was a professionally qualified organization it wanted sufficient

    time to prepare the EIA report by conducting fresh field studies to upgrade the project report .But

    the irrigation Secretaries were impatient and they wanted to somehow get a routine report on

    EIA done by other agencies who were willing to prepare the project in a shorter time for the

    routine purpose of submitting the project to the Union Ministry of Environment to secure the

    Environmental clearance within the shortest possible time.

    Naturally the EIA-EMP partly prepared by EPTRI was handed over to M/s AFC Ltd.

    Hyderabad for updating the same and this organization did not have sufficient number of experts

    in the different fields of ecology, hydrology and environmental sciences and engineering as

    experts who could be considered qualified as envisaged by article 45 of the Evidence Act. The

    relevant reports were not prepared in a comprehensive manner as per rules and regulations and

    without proper assessment of the dam break analysis report, risk analysis report, disaster

    management report and Environmental Management report including the different alternatives

    thoroughly analyzed for the Polavaram dam project . Hence such incomplete reporters were

    submitted by the AP State Government to the Union Ministry of Environment for obtaining

    environmental clearance in a great hurry.

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    8.CALCULATION OF FACTOR OF SAFETY BY VARYING DOWNSTREAM SLOPE

    OF RAMPADSAGAR DAM

    8.1. FOR 7/10 DOWNSTREAM SLOPE

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    FORCE NAME MAGNITUDE (KN) LEVER ARM

    (M)

    MOMENT DUE TO FORCRE

    AT TOE (KNM)

    WEIGHT DUE TO TRIANGULAR

    PORTION W1

    X57.58 X82.2 X23.5 X 1=

    55654.23

    38.38 +2136009.347

    WEIGHT DUE TO RECTANGULAR

    PORTIONW2

    96.87X 8.33X

    23.5X1=18962.78

    61.745 +1170857.27

    WEIGHT OF WATER SUPPORTED

    ON DOWNSTREAM W3

    X26.24X37.49X1X

    9.81=4825.23

    8.746 +42201.46

    UPLIFT U1 522.26 X 6.061 62.879 -199038.30

    UPLIFT U2 X308.90 X6.061 63.889 -59823.35

    UPLIFT U3 367.77X 59.849 29.92 -658559.14

    UPLIFT U4 X59.849 X154.49 39.89 -184412.90

    WATER PRESSURE ON UPSTREAM

    FACE

    X 84.73 X831.24 28.24 -994532.03

    WATER PRESSURE ON

    DOWNSTREAM FACE

    X367.77 X37.49 12.496 +86145.52

    EARTH QUAKE FORCE, VERTICAL

    (UPWARD)

    0.05 X 74617.01=

    -3730.85

    0.05 X 3306866.617=

    -165343.33

    HORIZONTAL EARTHQUAKE ,

    WORST CASE TOWARDS

    DOWNSTREAM, PW1,DUE TO

    TRIANGULAR PORTION

    0.1 X 55654.23 =

    - 5565. 423

    27.4 -152492.59

    PW2,DUE TO

    RECTANGULAR PORTION

    0.1 X 18962.78= 1896.278 48.43 -91836.74

    HYDRODYNAMIC FORCE , Pe .555 X 0.1 X 84.73 X 9.81= 4H/3 =

    (4 X

    84.73)/3

    =35.96

    -1658.85

    WAVE FORCE ,Pw Hw= 0.032 X(V.F)1/2

    +0.763-0.271 (F)3/4

    TAKING V=40 KMPH

    AND FETCH=5KM

    Hw=0.309 M

    19.62 X.3092=1.873

    3/8

    X.309+84.73

    -158.91

    M+VE/MVE =1.369 APPROX= 1.37

    M +VE = MVE=

    +2136009.34 -199038.30

    +1170857.27 -59823.35

    +42201.46 -658559.14

    +86145.52 -184412.90

    -994532.03

    -165343.33

    -152492.59

    -91836.74

    -1658.85

    -158.91

    =+3435214 =-2507856

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    8.2. FOR 8/10 DOWNSTREAM SLOPE

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    FORCE NAME MAGNITUDE (KN) LEVER ARM

    (M)

    MOMENT DUE TO FORCRE

    AT TOE (KNM)

    WEIGHT DUE TO TRIANGULAR

    PORTION W1

    WEIGHT DUE TO RECTANGULAR

    PORTIONW2

    WEIGHT OF WATER SUPPORTED

    ON DOWNSTREAM W3

    UPLIFT U1

    UPLIFT U2

    UPLIFT U3

    UPLIFT U4

    WATER PRESSURE ON UPSTREAM

    FACE

    WATER PRESSURE ON

    DOWNSTREAM FACE

    EARTH QUAKE FORCE, VERTICAL

    (UPWARD)

    HORIZONTAL EARTHQUAKE ,

    WORST CASE TOWARDS

    DOWNSTREAM, PW1,DUE TO

    TRIANGULAR PORTION

    PW2,DUE TO

    RECTANGULAR PORTION

    HYDRODYNAMIC FORCE , Pe

    WAVE FORCE ,Pw

    M+VE/MVE =

    M +VE = MVE=

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    8.3.FOR 6/10 DOWNSTREAM SLOPE

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    FORCE NAME MAGNITUDE (KN) LEVER ARM

    (M)

    MOMENT DUE TO FORCRE

    AT TOE (KNM)

    WEIGHT DUE TO TRIANGULAR

    PORTION W1

    WEIGHT DUE TO RECTANGULAR

    PORTIONW2

    WEIGHT OF WATER SUPPORTED

    ON DOWNSTREAM W3

    UPLIFT U1

    UPLIFT U2

    UPLIFT U3

    UPLIFT U4

    WATER PRESSURE ON UPSTREAM

    FACE

    WATER PRESSURE ON

    DOWNSTREAM FACE

    EARTH QUAKE FORCE, VERTICAL

    (UPWARD)

    HORIZONTAL EARTHQUAKE ,

    WORST CASE TOWARDS

    DOWNSTREAM, PW1,DUE TO

    TRIANGULAR PORTION

    PW2,DUE TO

    RECTANGULAR PORTION

    HYDRODYNAMIC FORCE , Pe

    WAVE FORCE ,Pw

    M+VE/MVE =

    M +VE = MVE=

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    8.4 .FOR 5/10 DOWNSTREAM SLOPE

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    FORCE NAME MAGNITUDE (KN) LEVER ARM

    (M)

    MOMENT DUE TO FORCRE

    AT TOE (KNM)

    WEIGHT DUE TO TRIANGULAR

    PORTION W1

    WEIGHT DUE TO RECTANGULAR

    PORTIONW2

    WEIGHT OF WATER SUPPORTED

    ON DOWNSTREAM W3

    UPLIFT U1

    UPLIFT U2

    UPLIFT U3

    UPLIFT U4

    WATER PRESSURE ON UPSTREAM

    FACE

    WATER PRESSURE ON

    DOWNSTREAM FACE

    EARTH QUAKE FORCE, VERTICAL

    (UPWARD)

    HORIZONTAL EARTHQUAKE ,

    WORST CASE TOWARDS

    DOWNSTREAM, PW1,DUE TO

    TRIANGULAR PORTION

    PW2,DUE TO

    RECTANGULAR PORTION

    HYDRODYNAMIC FORCE , Pe

    WAVE FORCE ,Pw

    M+VE/MVE =

    M +VE = MVE=

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    8.5 .FOR 9/10 DOWNSTREAM SLOPE

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    FORCE NAME MAGNITUDE (KN) LEVER ARM

    (M)

    MOMENT DUE TO FORCRE

    AT TOE (KNM)

    WEIGHT DUE TO TRIANGULAR

    PORTION W1

    WEIGHT DUE TO RECTANGULAR

    PORTIONW2

    WEIGHT OF WATER SUPPORTED

    ON DOWNSTREAM W3

    UPLIFT U1

    UPLIFT U2

    UPLIFT U3

    UPLIFT U4

    WATER PRESSURE ON UPSTREAM

    FACE

    WATER PRESSURE ON

    DOWNSTREAM FACE

    EARTH QUAKE FORCE, VERTICAL

    (UPWARD)

    HORIZONTAL EARTHQUAKE ,

    WORST CASE TOWARDS

    DOWNSTREAM, PW1,DUE TO

    TRIANGULAR PORTION

    PW2,DUE TO

    RECTANGULAR PORTION

    HYDRODYNAMIC FORCE , Pe

    WAVE FORCE ,Pw

    M+VE/MVE =

    M +VE = MVE=

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    9.CALCULATION OF FACTOR OF SAFETY BY VARYING UPSTREAM SLOPES

    9.1 .FOR 2/10 UPSTREAM SLOPE

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    FORCE NAME MAGNITUDE (KN) LEVER ARM

    (M)

    MOMENT DUE TO FORCRE

    AT TOE (KNM)

    WEIGHT DUE TO TRIANGULAR

    PORTION W1

    WEIGHT DUE TO RECTANGULAR

    PORTIONW2

    WEIGHT OF SMALL TRIANGULAR

    PORTION ON UPSTREAM W3

    WEIGHT OF WATER SUPPORTED

    ON DOWNSTREAM W4

    WEIGHT OF WATER SUPPORTED

    ON UPSTREAM(RECTANGLE) W5

    WEIGHT OF WATER SUPPORTED

    ON UPSTREAM(TRIANGLE) W6

    UPLIFT U1

    UPLIFT U2

    UPLIFT U3

    UPLIFT U4

    WATER PRESSURE ON UPSTREAM

    FACE

    WATER PRESSURE ON

    DOWNSTREAM FACE

    EARTH QUAKE FORCE, VERTICAL

    (UPWARD)

    HORIZONTAL EARTHQUAKE ,

    WORST CASE TOWARDS

    DOWNSTREAM, PW1,DUE TO

    TRIANGULAR PORTION

    PW2,DUE TO

    RECTANGULAR PORTION

    PW3,DUE TO SMALL TRIANGULAR

    PORTION ON UPSTREAM

    HYDRODYNAMIC FORCE , Pe

    WAVE FORCE ,Pw

    M+VE/MVE =

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    9.2 .FOR 3/10 UPSTREAM SLOPE

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    FORCE NAME MAGNITUDE (KN) LEVER ARM

    (M)

    MOMENT DUE TO FORCRE

    AT TOE (KNM)

    WEIGHT DUE TO TRIANGULAR

    PORTION W1

    WEIGHT DUE TO RECTANGULAR

    PORTIONW2

    WEIGHT OF SMALL TRIANGULAR

    PORTION ON UPSTREAM W3

    WEIGHT OF WATER SUPPORTED

    ON DOWNSTREAM W4

    WEIGHT OF WATER SUPPORTED

    ON UPSTREAM(RECTANGLE) W5

    WEIGHT OF WATER SUPPORTED

    ON UPSTREAM(TRIANGLE) W6

    UPLIFT U1

    UPLIFT U2

    UPLIFT U3

    UPLIFT U4

    WATER PRESSURE ON UPSTREAM

    FACE

    WATER PRESSURE ON

    DOWNSTREAM FACE

    EARTH QUAKE FORCE, VERTICAL

    (UPWARD)

    HORIZONTAL EARTHQUAKE ,

    WORST CASE TOWARDS

    DOWNSTREAM, PW1,DUE TO

    TRIANGULAR PORTION

    PW2,DUE TO

    RECTANGULAR PORTION

    PW3,DUE TO SMALL TRIANGULAR

    PORTION ON UPSTREAM

    HYDRODYNAMIC FORCE , Pe

    WAVE FORCE ,Pw

    M+VE/MVE =

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    9.3 .FOR 4/10 UPSTREAM SLOPE

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    FORCE NAME MAGNITUDE (KN) LEVER ARM

    (M)

    MOMENT DUE TO FORCRE

    AT TOE (KNM)

    WEIGHT DUE TO TRIANGULAR

    PORTION W1

    WEIGHT DUE TO RECTANGULAR

    PORTIONW2

    WEIGHT OF SMALL TRIANGULAR

    PORTION ON UPSTREAM W3

    WEIGHT OF WATER SUPPORTED

    ON DOWNSTREAM W4

    WEIGHT OF WATER SUPPORTED

    ON UPSTREAM(RECTANGLE) W5

    WEIGHT OF WATER SUPPORTED

    ON UPSTREAM(TRIANGLE) W6

    UPLIFT U1

    UPLIFT U2

    UPLIFT U3

    UPLIFT U4

    WATER PRESSURE ON UPSTREAM

    FACE

    WATER PRESSURE ON

    DOWNSTREAM FACE

    EARTH QUAKE FORCE, VERTICAL

    (UPWARD)

    HORIZONTAL EARTHQUAKE ,

    WORST CASE TOWARDS

    DOWNSTREAM, PW1,DUE TO

    TRIANGULAR PORTION

    PW2,DUE TO

    RECTANGULAR PORTION

    PW3,DUE TO SMALL TRIANGULAR

    PORTION ON UPSTREAM

    HYDRODYNAMIC FORCE , Pe

    WAVE FORCE ,Pw

    M+VE/MVE =

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    9.4 .FOR 5/10 UPSTREAM SLOPE

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    FORCE NAME MAGNITUDE (KN) LEVER ARM

    (M)

    MOMENT DUE TO FORCRE

    AT TOE (KNM)

    WEIGHT DUE TO TRIANGULAR

    PORTION W1

    WEIGHT DUE TO RECTANGULAR

    PORTIONW2

    WEIGHT OF SMALL TRIANGULAR

    PORTION ON UPSTREAM W3

    WEIGHT OF WATER SUPPORTED

    ON DOWNSTREAM W4

    WEIGHT OF WATER SUPPORTED

    ON UPSTREAM(RECTANGLE) W5

    WEIGHT OF WATER SUPPORTED

    ON UPSTREAM(TRIANGLE) W6

    UPLIFT U1

    UPLIFT U2

    UPLIFT U3

    UPLIFT U4

    WATER PRESSURE ON UPSTREAM

    FACE

    WATER PRESSURE ON

    DOWNSTREAM FACE

    EARTH QUAKE FORCE, VERTICAL

    (UPWARD)

    HORIZONTAL EARTHQUAKE ,

    WORST CASE TOWARDS

    DOWNSTREAM, PW1,DUE TO

    TRIANGULAR PORTION

    PW2,DUE TO

    RECTANGULAR PORTION

    PW3,DUE TO SMALL TRIANGULAR

    PORTION ON UPSTREAM

    HYDRODYNAMIC FORCE , Pe

    WAVE FORCE ,Pw

    M+VE/MVE =

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    10.GRAPHICAL REPRESENTATIONS

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    11.CONCLUSIONS