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## Civil engineering

Civilengineering Subjects tutorial : A branch of engineering that encompasses the conception, design, construction, and management of residential and commercial buildings and structures, water supply facilities, and transportation systems for goods and people, as well as control of the environment for the maintenance and improvement of the quality of life. Civil engineers include planning and design professionals in both the public and private sectors, contractors, builders, educators, and researchers.

Civil engineers play a major role in developing workable solutions to construct, renovate, repair, maintain, and upgrade infrastructure. The infrastructure includes roads, mass transit, railroads, bridges, airports, storage buildings, terminals, communication and control towers, water supply and treatment systems, storm water control systems, wastewater collection, treatment and disposal systems, as well as living and working areas, recreational buildings, and ancillary structures for civil and civic needs. Without a well-maintained and functioning infrastructure, the urban area cannot stay healthy, grow, and prosper.

Some of the subsets that civil engineers can specialize in include photogrammetry, surveying, mapping, community and urban planning, and waste management and risk assessment. Various engineering areas that civil engineers can specialize in include geotechnical, construction, structural, environmental, water resources, and transportation engineering. See Civil engineering, Coastal engineering, Construction engineering, Engineering, Environmental engineering, Highway engineering, River engineering, Surveying, Transportation engineering

## Introduction Spillways

INTRODUCTION Spillway is a structure, use to pass surplus flood water from reservoir to the downstream side of the dam. It is sometimes also know surplussing work, as its main job is to handle the surplus water. It is a sort of safety valve for a dam. During floods, the reservoir level goes on increasing, as more and more water enters the reservoir. If spillways had not been there, the level in the reservoir will go on rising even beyond the maximum reservoir level. This may lead to over topping of the dams. Additional stresses may be induced in the dam and this may cause failure of the dam. More rise in water level beyond the maximum flood level will cause submergence of vast additional areas and may cause suffering to the people living on the U/S side. Spillways act as safety valve for the safety of the dam and…

SUPPLY SLUICES IN GRAVITY DAMS

## Supply sluices in gravity dams

SUPPLY SLUICES IN GRAVITY DAMS Some openings in the dam have to be provid so as to pass the excess flow D/S of the dam. These openings are know outlet sluices or supply sluices. If water from the reservoir is to be release for irrigation purpose at a controll rate, it is done with the help of these supply sluices. All the supply sluices are fitted with gates which can be raise or lowere. The control on the gates is exercise from the top of the dam. The gates are fitted in the grooves form at the sides of the openings in the dam. When gates are lowere they stop flow of water and when raised they again start discharging water D/S. Sluices may be provided at more than one depth. By this, water can be drawn from different elevations or depths. Supply sluices are also sometimes used to scour…

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## Concrete dam and Gravity dam

ADVANTAGES OF CONCRETE DAMS There are some advantages of concrete dams described as following: The maintenance cost of gravity dams is very small. Spill ways can be installed in the dam itself and no separate site for them is required. They can be constructed for very large heights. Ice and other outer effects do not affect the stability of the dam. Water is not lost by seepage. Outlet sluices may be installed in the dam. At valleys where side slopes are very steep, only this dam is found as the most suitable choice. This dam gives pre-warning before failure. If timely measures are taken, the dam may even be made safe. DISADVANTAGES OF GRAVITY DAMS There are some disadvantages of concrete dams as below: 1. They are very costly. 2. They require very skilled labor for construction. 3. They have to be continuously cured during construction. 4. Large calculation work…

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FOUNDATION TREATMENT OF THE GRAVITY DAMS

## foundation treatment of gravity dam

FOUNDATION TREATMENT OF THE GRAVITY DAMS The foundation of the gravity dam should be hard, strong, durable and impervious. The imperviousness of the foundation is very important as uplift pressure depends greatly upon the seepage. Uplift pressure is increase when seepage is more. Hence to render the foundation water proof or impervious, it has to be suitably treat. All the loose overlying soil from the site is removed and solid rocky foundation is reach. The rocky foundation should also be excavated for some depth so that the proposed dam fits in the rock. This aspect will prevent the sliding of the dam over its foundation. A 3 cm thick layer of rich cement mortar should be laid on the excavated rocky foundation before concreting is done over it. All the faults, seams, cavernous rocks, crushed zones etc., should be either made good or removed from the foundation site. In order…

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CONTROL OF CONCRETE DAM CRACKING

## Control of concrete dams cracking

CONTROL OF CONCRETE DAM CRACKING When cement starts setting, heat of hydration is developed. Concrete dams are large masses of concrete. The heat of hydration is dissipated easily from the surface of the dam as the surface remains exposed to the atmosphere. It is very difficult to dissipate the heat of hydration from the interior of the dam. If some arrangement for this is not made, very high temperatures may develop inside the dam. The surface of the dam being cool and temperature in the interior being very high, cracks are likely to develop and cause difficulties. The dam may also develop surface cracks due to daily variation of the temperature at the surface. Surface cracks are not harmful for short durations but cause very bad effects in the long run. Water enters the surface cracks and solidifies to ice if the temperature falls down to zero. The ice thus…

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GALLERIES IN GRAVITY DAMS

## Joints in gravity dams

JOINTS IN GRAVITY DAMS The joints that are necessarily provided in the dam may be classified under two heads. 1. Construction joints, and 2. Contraction joints. 1. Construction Joints. The concreting of the dam is not done at a stretch but in stages. Each stage of the concreting is known as lift. Lift is nothing but thickness of a horizontal layer of concreting laid once. In concrete dams the thicknessof each layer or in other words the lift, is kept about 1.5 m.   The horizontal joint between two successive lifts is known as construction joint. The lift or thickness of each concreting layer is decided so that cooling of the concrete, while setting, may be effectively accomplished by natural as well as artificial agencies. Thickness of lower most layer of concreting is kept half i.e. about 0.75 m. Modern techniques of treatment of surface before laying the new layer…

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GALLERIES IN GRAVITY DAMS

## Galleries in gravity dam

GALLERIES IN GRAVITY DAMS 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. They are provided at all the levels of the dam. 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 collect at some central place from where it is discharged into the D/S side of the dam. Galleries are constructed to perform the following functions. 1. It may be cement concrete or masonary dam, some water definitely seeps through the joints and pores of…

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DESIGN OF GRAVITY DAMS

## Design of gravity dams

DESIGN OF GRAVITY DAMS Elementary profile of the gravity dam has already been discusse. It is not possible to adopt elementary profile as such, because of certain practical requirements. The preliminary design of gravity dams is done by two dimensional gravity method by considering the dam as being made of a number of cantilevers of unit length and acting independently of adjacent cantilevers. (a) Effect of top width added at the apex of triangular profile. ABC is an elementary profile of the dam. Let a be the top width added at the apex. The effect of this added top width is that the resultant of the dam section would shift slightly towards U/S side when reservoir is empty. For all the dam sections lying below point H or section FHG the resultant would be shifted towards the U/S face of the line AE1. This shift in resultant causes development of…

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PROFILE OF HIGH MASONRY GRAVITY DAM

## Profile of high masonry gravity dam

PROFILE OF HIGH MASONRY GRAVITY DAM Mr. G. Molesworth gave the following formulae for fixing. These formulae are applicable for masonry gravity dams only. $x= \sqrt{\frac{1.76y^{3}}{p_{a+1.06y}}}$ But value of x should not exceed y ρ at any cost $Z= \frac{y}{36.5p_{a}}$ where x = D/S offset from the vertical line also known as axis of the dam at a depth y below the maximum reservoir level. Z = U/S offset from the vertical line at a depth y metres. b1 = Base width of the dam at 4 h below the full reservoir level. a = Thickness of the dam at the full reservoir level. It is taken as 0.4 b1. pa = Allowable compressive stress for masonry in t/m2, the value of which may vary between 77 to 110 t/m2.

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PRACTICAL PROFILE OF A GRAVITY DAM

## Practical profile of a gravity dam

PRACTICAL PROFILE OF A GRAVITY DAM The elementary profile cannot be adopted as such. Some modifications have to be incorporated, to make it adaptable in practice. Modifications in elementary profile are necessitated due to following reasons: 1. Some free board is essential whereas elementary profile does not provide any free board. 2. Road way is generally provided at the top of the dam. This necessitates quite thick top of the dam, whereas elementary profile does not provide any thickness at the top. 3. Additional load due to extra height, provided for free board and also due thick top of the dam, induces some additional stress in the dam section. Some extra darn section has to be provided at the base of the dam along the U/S face to counter act such additional stresses. The amount of free board usually provided is 1.5 hw where hw is the height of waves…

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