Types of hydraulic structures are distinguished, first of all, by their functional purpose.

Distinguish the following types:

− water retaining structures;

− water discharge structures;

− drainage and water outlet structures;

− water supply structures;

− energy structures;

− shipping facilities;

− bank protection and shore protection structures, etc.

Water retaining structures create and maintain a level difference between the upper and lower pools (pressure).

Water discharge structures must provide:

− skipping high water flows and rain floods and other unused water flows in order to avoid exceeding the design water levels in the upper pool;

− passage of ice, slush, debris and other floating objects from the upper pool to the lower pool, if this is required by the operating conditions of the waterworks.

These functions of spillway structures can be performed both during the operation of the hydroelectric complex and during its construction. In the first case, spillway structures are called operational, in the second case - construction or structures for passing construction costs.

Drainage structures are necessary to release water from the reservoir, in particular, to maintain certain sanitary and environmental conditions in the downstream (the so-called sanitary water flows established by sanitary rules and regulations - SanPiN 3907-85).

Water supply structures are designed to transmit water over certain distances.

Energy structures are used to use water energy - these are the structures of hydraulic (HPP), nuclear (NPP), thermal (TPP) power plants, as well as the construction of pumping stations (PS).

Shipping facilities provide navigation and timber rafting.

Bank protection and bank strengthening structures are designed to protect or strengthen the banks of rivers, canals, and reservoirs from destruction by waves, water flow, and ice.

1.3. Hydraulic structures of cities

In urban areas the following are widely used:

– water retaining structures;

− water discharge structures;

− drainage and water outlet structures;

− water supply structures;

– reservoirs (ponds);

− bank protection and shore protection structures;

– structures to protect territories from landslide phenomena;

– structures to protect territories from flooding and flooding.

2. Water retaining structures

2.1. Types of water retaining structures

Dams are most widely used as water retaining structures. Depending on the purpose of the hydraulic system, retaining structures can be buildings of hydroelectric power stations and pumping stations, abutments, retaining walls, etc.

Dams are built from various materials: soil (stone), concrete and reinforced concrete, wood, synthetic materials. In accordance with SNiP 2.06.05-84* they are divided into types (Table 2.1).

Table 2.2

Typification of dams made of soil materials

Dam type	Features
Earth fill	Soils range from clayey to gravel-pebble; pour dry with compaction or into water
Alluvial soil	Soils range from clayey to gravel-pebble; washed by means of hydromechanization
Stone-earth	The soils of the body are coarse-grained; anti-filtration devices - from clay to fine sand
Rockfill	The soils of the body are coarse-grained; anti-filtration devices - from non-soil materials

Based on the design of the body and anti-seepage devices in the body and base, earthen embankment dams are divided (SNiP 2.06.05-84*) into main types (Fig. 2.3 and Table 2.3).

Table 2.3

Types of earth embankment dams

Dam elements

Type of dam

Dam body

Homogeneous (Fig. 2.3, A).

Heterogeneous (Fig. 2.3, b, V).

With a screen made of non-ground materials (Fig. 2.3, G).

With a soil core - vertical or inclined (Fig. 2.3, d).

With a non-ground diaphragm (Fig. 2.3, e).

With ground screen (Fig. 2.3, and).

Anti-seepage device at the base of the dam

With tooth (Fig. 2.3, G).

With injection curtain (Fig. 2.3, d).

With a wall, tongue and groove (Fig. 2.3, e).

With dejection (Fig. 2.3, and).

Rice. 2.3. Types of earth embankment dams:

1 – dam body; 2 – depression surface; 3 – drainage; 4 – fastening of slopes; 5 – top ground anti-filtration prism; 6 – diaphragm; 7 – top prism; 8 – bottom prism; 9 – transition layer; 10 – screen made of non-ground materials; 11 – soil core; 12 – central soil impervious prism; 13 – tongue or wall; 14 – dejected; 15 – injection (cementation) curtain (hanging); 16 – tooth; 17 – ground screen; h – dam height; b – width of the dam at the bottom; b um – width of the anti-filtration device at the bottom; b up – width of the dam along the crest; m h – coefficient of uphill slope; m t – downstream slope coefficient

Alluvial dams, depending on the soils of the dam body and construction methods, are divided (SNiP 2.06.05-84*) into main types (Fig. 2.4 and Table 2.4).

Table 2.4

Types of earthen alluvial dams

Type of dam	Dam body soils	Dam construction method
Homogeneous: with forced-formed slopes (Fig. 2.4, A) with freely formed slopes (Fig. 2.4, b)	Sands, sandy loams, loams Sands, gravel (wood)	One-sided alluvium with embankment dams on the lower slope and central alluvium without embankment dams
Heterogeneous:: with the core (Fig. 2.4, V) with a central zone (Fig. 2.4, G)	Gravel, pebble containing sand and clay fractions Gravel, pebble or sandy, mixed-grain	Double-sided alluvium with embankment dams on slopes
Combined: with a bulk core of clay soil and alluvial side zones (Fig. 2.4, d) with bulk banquettes and an alluvial central zone (Fig. 2.4, e)	Gravel, pebble or sand	Double-sided alluvium without settling pond

To organize the drainage of water filtered through the body and base of the dam, to prevent the filtration flow from reaching the lower slope, to reduce the depression surface, and for other purposes, drainages can be installed in the body of earthen dams (Fig. 2.7).

Rock-earth and rock-fill dams are divided into main types according to the design of the anti-seepage devices and the method of work (SNiP 2.06.05-84*) (Fig. 2.5 and 2.6, Table 2.5).

Rice. 2.4. Types of alluvial dams:

1 – fastening of the upper slope; 2 – drainage; 3 – alluvial core; 4 - alluvial intermediate zones; 5 – alluvial side zones; 6 – alluvial central weakly permeable zone; 7 – side bulk prisms (banquets); 8 – earthquake-resistant fastening of the slope; 9 – bulk clay core

Table 2.5

Types of stone dams

In addition to dams made of soil materials, concrete and reinforced concrete dams are sometimes used as water retaining structures for hydraulic structures on small rivers. Depending on the design and technological purpose, these dams are divided (SNiP 2.06.06-85) into main types (Table 2.6).

Table 2.6

Types of dams made of concrete (reinforced concrete)

Hydraulic structures (HTC) include pressure front structures and natural dams (dams, locks, dams, irrigation systems, dams, dams, canals, storm drains, etc.), creating a difference in water levels before and after them, intended for use water resources, as well as to combat the harmful effects of water.

A dam is an artificial water-retaining structure or a natural (natural) obstacle in the path of a watercourse, creating a difference in levels in its upper and lower reaches along the river bed; is an important type of general hydraulic structure with culverts and other devices created with it.

Artificial dams are created by man for his own needs; These are dams of hydroelectric power stations, water intakes in irrigation systems, dams, dams, and dams that create a reservoir in their upstream. Natural dams are the result of natural forces: landslides, mudflows, avalanches, landslides, earthquakes.

Pool - a section of a river between two adjacent dams on a river or a section of a canal between two locks.

The upstream of a dam is the part of the river above the retaining structure (dam, sluice).

Tailwater is the part of the river below the retaining structure.

An apron is a reinforced section of a river bed in the downstream of a spillway hydraulic structure that protects the bed from erosion and equalizes the flow speed.

Reservoirs can be long-term or short-term. A long-term artificial reservoir is, for example, the reservoir of the upper pool of the Iriklinskaya State District Power Plant. A long-term natural reservoir is formed due to the blocking of rivers by a collapse of solid rocks (Tian Shan, Pamir mountains, etc.).

Short-term artificial dams are built to temporarily change the direction of the river bed during the construction of hydroelectric power stations or other hydraulic structures. They arise as a result of blocking the river with loose soil, snow or ice (jams, constipation).

As a rule, artificial and natural dams have drains: for artificial dams - directed, for natural - randomly formed (spontaneous). There are several classifications of hydraulic structures. Based on the location of the GTS, they are divided into:

on land (pond, river, lake, sea);
underground pipelines, tunnels.

Based on the nature and purpose of use, the following types of hydraulic structures are distinguished:

water and energy;
for water supply;
reclamation;
sewer;
water transport;
decorative;
timber smelting;
sports;
fisheries.

According to their functional purpose, hydraulic structures are classified as follows:

water-retaining structures that create pressure or a difference in water levels in front of and behind the structure (dams, dikes);
water supply structures (water conduits) used to transfer water to specified points (canals, tunnels, flumes, pipelines, sluices, aqueducts);
regulatory (correction) structures designed to improve the conditions for the flow of watercourses and protect river beds and banks (shields, dams, half-dams, bank protection, ice guide structures);
spillway structures used to pass excess water from reservoirs, canals, pressure basins, which allow partial or complete emptying of reservoirs.

Special hydraulic structures are included in a special group:

GTS for the use of water energy - hydroelectric power station buildings and pressure pools;
GTS for water transport - shipping locks, log chutes;
reclamation hydraulic structures - main and distribution canals, gateways, regulators;
fishery hydraulic structures - fish passages, fish ponds;
complex hydraulic structures (waterworks) - hydraulic structures united by a common network of dams, canals, locks, power plants, etc.

The types and classification of which indicate a wide range of their uses. Any of these structures are built on water resources - from rivers and lakes to seas or groundwater - and are necessary to combat the destructive force water element. Each of the systems has its own characteristics of construction and operation.

How are they classified?

Hydraulic structures are understood as systems that make it possible to beneficially use or prevent the harmful effects of excess water on environment. All modern watersheds, land reclamation) are called "hydraulic structures". Their types and classification, depending on the features of installation and operation, are as follows:

sea, lake, river or ponds;
above ground or underground;
served by the water sector;
used by various industries.

Modern hydraulic structures include dams, dikes, spillways, water intakes, and canals. In general, any systems that are installed on

Water-retaining

Water-retaining hydraulic structures are structures that can be used to create pressure or provide a difference in front of and behind the dam. Experts say that the water regime in the backwater zone changes depending on the natural and climatic conditions of the region. Water-retaining hydraulic structures are the most important structures for creating dams, since they account for huge pressure due to water pressure. If the water-retaining structure suddenly fails, the pressure front of the water will be difficult to control, and this can lead to dire consequences.

Water-conducting

Water supply structures consist of water intakes, spillways, spillways and channels. These are hydraulic structures used to transfer water to specified points. Water intake systems that take water from a reservoir and supply it to hydropower, water supply or irrigation facilities deserve special attention. Their task is to ensure the passage of water into the water pipeline in the established volume, quantity and quality in accordance with the water consumption schedule. Depending on the location it may be:

surface: water is taken at the level of the free surface;
deep: water is taken under the level of the free surface;
bottom: water is taken from the lowest section of the watercourse;
tiered: with this structure, water is taken from several levels - this depends on its level in the reservoir itself and on its quality at different depths.

Most often, water intake hydraulic structures are installed on rivers. The photo shows that such structures can be high and low.

Water intakes for different reservoirs

Depending on the type of source, water intakes can be river, lake, sea, or reservoir. Among river structures, the most popular are coastal, floating, and channel ones, which can be combined with pumping stations or mounted separately:

A shore structure must be installed if the bank is steep. This design consists of water intake hydraulic structures consisting of concrete or reinforced concrete with a large diameter. The photo shows that the front wall faces the shore.
Channel systems are placed on and are distinguished by a head placed in
Floating structures are a pontoon or barge with pumps installed on them, through which water is taken from the river and supplied through pipes to the shore.
Bucket water intake systems take water from a reservoir using a bucket located on the shore.

Regulatory

Regulatory hydraulic structures - what are they? In another way, they are called straightening structures, as they allow you to regulate the flow of rivers. This can be achieved through the construction of stream-directing and limiting structures in the riverbed itself and along the banks of the reservoir. Thanks to such systems, the river flow is formed so that it moves at a relatively low speed and thereby maintains a fairway with predetermined minimum values of width, depth and curvature. These hydraulic structures are popular, the types and classification of which are as follows:

capital structures that are part of general systems for regulating rivers and aimed at long-term use;
lightweight structures, which are otherwise called temporary and are used mainly on rivers of small and medium volume.

The first structures consist of dams, enclosing shafts, dams and ideally cope with the erosion and destructive effects of water. Light control structures are curtains, wattles made of brushwood, which simply direct or deflect the flow of the device.

Irrigation hydraulic structures

Types and classification suggest division according to the presence of dams - damless or dammed. The first systems involve the creation of an artificial canal, which departs from the river at a certain angle and takes away part of the flow of the watercourse. To prevent sediment from the bottom from entering the irrigation canal, such structures are located on concave sections of the shore. If water flows are significant, then the construction of dam structures is required, which, in turn, can be surface or deep.

Culverts

Culvert hydraulic structures are spillways and spillways. These systems are classified as controlled or automatic. With the help of a spillway, excess water is discharged from a reservoir, and a spillway is a system in which water flows freely over the crest of a water-retaining structure. Depending on the characteristics of water movement, such systems can be without pressure or pressure.

Special purpose

Among the special-purpose hydraulic structures are: hydropower structures, irrigation and drainage structures, reclamation systems and water transport structures. Let's take a closer look at these structures:

Hydroelectric power structures can be built-in, run-of-river, dam-based or diversional. Such systems consist of water intake structures, pressure pipelines, turbines with generators, outlet pipelines and different types shutters Hydroelectric power stations are needed to convert the energy of water flow into electricity.
Water transport: these systems consist of locks, ship lifts, port facilities, which are installed on rivers and canals with different water levels in them.
Reclamation: these systems allow you to think through measures aimed at radical improvement of land. As part of land reclamation, areas are drained and irrigated. Using the drainage system, excess moisture is removed, and the irrigation system ensures timely watering of the territory. Drainage systems can be horizontal or vertical.
Fish passages: these hydraulic structures ensure the passage of fish from the lower water level to the upper one, mainly during its spawning migration. There are two types of such systems: the first involve the independent passage of fish through special fish passages, the second - through special fish passage sluices and fish lifts.
Settling tanks: they are special storage tanks where industrial waste and wastewater are collected.

In some cases, general and special structures are combined, for example, a spillway system is placed in a hydroelectric power station building. Such complex systems are called units of hydraulic structures.

What danger?

There is also a division of hydraulic structures according to the degree of their danger: they can be low, medium, high or extremely high degree danger. Most often, the main factors influencing the danger of hydraulic structures are natural loads and impacts, non-compliance of the design solution with regulatory requirements, violation of operating conditions of structures or consequences and damage due to an accident. Any shortcomings and unpredictable impacts can lead to the destruction of structures and a breakthrough of the pressure front.

Chapter 9 Hydrodynamic accidents

9.1. Hydraulic structures

Hydraulic structures and their classifications

TO hydraulic structures (TTC) include pressure front structures

And natural dams (dams, sluices, dams, irrigation systems, dams, dams, canals, storm drains, etc.), creating a difference in water levels before and after them, designed to use water resources, as well as to combat the harmful effects of water.

Pool - a section of a river between two adjacent dams on a river or a section of a canal between two locks.

Upstream of the dam - part of the river above a retaining structure (dam, sluice). Downstream – part rivers below the retaining structure.

An apron is a reinforced section of a river bed in the downstream of a spillway hydraulic structure that protects the bed from erosion and equalizes the flow speed.

As a rule, artificial and natural dams have drains: for artificial dams - directed, for natural ones - randomly formed (spontaneous).

There are several classifications of hydraulic structures.

Based on their location, GTS are divided into:

on land (pond, river, lake, sea);

underground pipelines, tunnels.

By nature and purpose of use The following types of hydraulic structures are distinguished:

water and energy;

for water supply;

reclamation;

V. A. Makashev, S. V. Petrov. “Dangerous situations of a man-made nature and protection from them: a textbook”

sewer;

water transport;

decorative;

timber smelting;

sports;

fisheries.

By functional purpose GTS are classified as follows:

water retaining structures, creating pressure or difference in water levels in front of and behind the structure (dams, dikes);

water supply structures(water conduits) used to transfer water to specified points (canals, tunnels, flumes, pipelines, sluices, aqueducts);

regulatory (correction) structures,designed to improve the conditions for the flow of watercourses and protect river beds and banks (shields, dams, half-dams, bank protection, ice guide structures);

water discharge structures, serving to pass excess water from reservoirs, canals, pressure basins, which allow partial or complete emptying of reservoirs.

IN a special group is distinguished special hydraulic structures:

GTS for the use of water energy - hydroelectric power station buildings and pressure pools;

GTS for water transport - shipping locks, log chutes;

reclamation hydraulic structures - main and distribution canals, sluices, regulating

fishery hydraulic structures – fish passages, fish ponds;

complex hydraulic structures (waterworks) - hydraulic structures united by a common network of dams, canals, locks, power plants, etc.

Classes of hydraulic structures

Hydraulic structures of the pressure front depending on possible consequences their destruction is divided into classes: hydroelectric power stations with a capacity of 1.5 million kW or more belong to class I, and those of lower power – to II–IV. Reclamation structures with an irrigation and drainage area of over 300 thousand hectares belong to class I, and with an area of 50 thousand hectares or less - to II–IV.

The class of the main permanent structures of the pressure front also depends on their height and the type of foundation soil (Table 16).

Table 16

Classes of the main permanent hydraulic structures of the pressure front, depending on their height and type of foundation soil

V. A. Makashev, S. V. Petrov. “Dangerous situations of a man-made nature and protection from them: a textbook”

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1. General Provisions

The branch of science and technology that, through the development of special complexes of structures, equipment and devices, deals with the use of water resources and combats their harmful effects is called hydraulic engineering.

In hydraulic engineering, the following main areas of its application have been identified:

the use of water energy, in which the energy of moving (falling) water is converted into mechanical and then electrical;

reclamation (improvement) of land by irrigating dry areas and draining wetlands, as well as by protecting them from the harmful effects of water (flooding, flooding, erosion, etc.);

water transport - improvement of navigable conditions of rivers and lakes, construction of ports, locks, canals, etc.;

water supply and sewerage for populated areas and industrial enterprises.

All of the listed branches of hydraulic engineering are not isolated, but are closely interconnected and intertwined in the complex solution of water management problems.

According to their purpose, hydraulic structures are divided into general and special. The first, used in all branches of hydraulic engineering, include: water-lifting structures that create pressure and maintain it - dams, dikes, etc.; culverts, serving for useful water intake or discharge of excess water; water supply - channels, trays, pipelines and tunnels; regulatory - for regulating channels, protecting banks from erosion, etc.; connecting, serving to connect pools and various hydraulic structures - drops, fast currents, abutments, separate bulls; ice and sludge disposal and sediment removal. For special hydraulic structures used only in certain conditions, include: hydropower - machine buildings of hydroelectric power stations, diversion structures; water transport - locks, canals, port facilities; irrigation and drainage - water intakes, water pipelines, treatment facilities.

Hydraulic structures are usually erected in the form of a complex of structures, including water-lifting, culvert, drainage, transport, energy, etc. Such a complex of structures is called a hydraulic complex. Depending on the purpose, there may be energy, irrigation or shipping (transport) waterworks. However, in most cases, complex waterworks are built that simultaneously solve several water management problems.

Hydraulic engineering construction creates an intensive engineering impact on natural conditions, changing the position of the basis of erosion of the surrounding area in the reservoir area, causing changes in the conditions of supply and movement of groundwater, activating slope processes (landslides), changing the microclimate of the area, etc. In addition, the creation of reservoirs with a large supply of water can cause catastrophic flooding of the river valley below the structure in the event of an accident. All this requires a particularly careful study of the territory where hydroelectric power stations are located.

During the design process, based on the purpose of the structures and specific natural conditions, the selection of the most rational site for the location of the main structures of the waterworks, its layout, the choice of the type and parameters of water-pressure structures, the depth of insertion and support on the base rocks, the interface with the rock mass adjacent to the sides of the valley, as well as the scheme of construction work.

The history of dams shows that those whose destruction caused terrible disasters collapsed in 2/3 of cases not due to errors in calculations or in the choice of material, but due to deficiencies in the foundations - on poor soils, often water-saturated, which was a consequence of insufficient awareness about the geological and hydrogeological conditions of foundation soils. An example of this is the disaster at the Vajont reservoir in Italy.

In 1959, at the VI Congress on large dams, Italian hydraulic engineers L. Semenza, N. Biadene, M Pancini reported on the world's highest arch dam on the river. Vayont, 265.5 m high (70 km north of Venice). The report covered the design features of the dam in great detail. To discharge flood waters on the crest of the dam, a spillway with 10 holes, each 6.6 m long, two tunnel and one bottom spillway was provided. To strengthen the base of the dam, area cementation of the rock is provided, with a drilling volume of 37,000 m3. To prevent filtration under the dam and on the banks, a grouting curtain was installed with a drilling volume of 50,000 m3. The dam was calculated on 4 analytical methods(independent arches, test loads, etc.). In addition, the dam design was studied on two models at the institute in Bergamo (scale 1:35). Model tests made it possible to lighten the dam by slightly reducing its thickness. About the geological conditions, it was only said that the Vayont valley is composed of limestones and dolomites, characteristic of the eastern Alps, that the layers fall upstream of the river and this is favorable for supporting the dam (Fig. 1).

The dam was completed in 1960, and on October 9, 1963, one of the worst disasters in the history of hydraulic engineering occurred, resulting in the death of more than 2,600 people. The cause was a landslide that collapsed into the reservoir. The world's tallest thin arch dam survived; all the designers' calculations turned out to be correct. As the analysis of materials after the disaster showed, geologists did not take into account the fact that the limestone layers form a synclinal fold, the axis of which coincides with the direction of the valley. At the same time, the northern wing is cut by a fault. In 1960, a landslide with a volume of 1 million m3 formed on the left bank near the dam.

In 1960-1961 a 2-kilometer catastrophic spillway tunnel was breached if landslides resume. To monitor the development of landslide processes, a network of geodetic benchmarks was laid, but as it turned out, the benchmarks did not cut the main sliding surface. From 1961-1963 a continuous gravitational creep was observed. Late in the evening of October 9, 1963, 240 million m3 of soil shifted into the reservoir in 30 seconds, at a speed of 15-30 m/s. A huge wave 270 m high crossed the 2-kilometer reservoir reservoir in 10 seconds, overflowed the dam and, sweeping away everything in its path, crashed into the valley. Seismic tremors were recorded in Vienna and Brussels.

Rice. 1. Geological section of the river valley. Vajont (Italy): 1 - Upper Cretaceous; 2 - Lower Cretaceous; 3 - malm; 4 - dogger; 5 - leyas. Numbers in circles: 1 - main sliding surface; 2 - slid block; 3 - fault; 4 - bottom of the glacial valley; 5 - direction of ancient cracks; 6 - direction of young cracks; 7 - reservoir

2. Waterworks

The hydroelectric power station on the lowland river includes a hydroelectric power station. In order for the turbines of a hydroelectric power station to operate, not only a continuous flow of water is required, but also a pressure - the difference in levels between the upper and lower pools, i.e. sections of the river upstream and downstream of the hydroelectric power station. The pressure is concentrated in a convenient location as a result of the construction of a dam or other water-retaining structure and the filling of the reservoir. These two elements are important components of the waterworks. A reservoir is also necessary to regulate the uneven flow of the river, bringing it into line with water consumption, i.e. V in this case with a graph of the electrical load of a hydroelectric power station. Hydroelectric power stations on high-water plain rivers are located in their bed and are called either low-pressure run-of-the-river hydroelectric power stations, or near-dam hydroelectric power stations if the pressure is high enough.

Since it is not economically feasible to accumulate rare high-water floods in the reservoir and since the consumption of electrical energy, i.e. the use of the water supply may be interrupted due to an accident; the hydroelectric complex must have a spillway to pass water from the upper pool to the lower pool, in addition to turbines, in order to avoid overflowing the reservoir and overflowing the water over the dam with the ensuing destructive consequences. In addition to the turbines, the passage of water into the lower pool in the event of a shutdown of hydroelectric power plant units may also be necessary when the reservoir is not filled, if without the supply of this water, water users located downstream - hydroelectric power plants, water transport, irrigation systems, etc. - will suffer damage. To solve this problem, culverts with deep holes - water outlets - are built as part of the hydraulic system.

The passage of water into the lower pool may also be necessary for the purpose of emptying the reservoir for inspection and repair of hydroelectric facilities. Then it should include drains with deep or bottom holes. To supply a large amount of water for its main purpose - to the turbines of a hydroelectric power station, clearing it of dangerous inclusions - ice, slush, sediment, litter, etc., special structures are needed - water intakes.

A hydroelectric power station may be located on a mountain river not near a dam, but downstream on the bank; water is supplied to it from the water intake by a special water conduit and is diverted from it into the river also by a special water conduit, which together are called diversion, and separately - inlet and outlet derivations. The purpose of the diversion device is the same as the construction of a dam, the concentration of pressure for its convenient use. In mountain rivers, water falls with a large surface slope, dissipating its potential energy. A canal laid along the shore with a minimal slope brings water to the hydroelectric power station with a surface level that differs little from the level of the upper pool.

As a result, the station uses greater pressure, the fall of a larger section of the river, not only due to the support of the dam, but also due to the difference in slopes of the river and the canal. The role of abductive derivation is similar; the water level in it differs little from the water level in the river at the end of the diversion, so that at the beginning of the outflow diversion at the hydroelectric power station the level is lower than nearby in a parallel flowing river. Thus, the station gains even greater pressure, using the fall of an additional section of the river. Diversion hydrosystems have a large extent, so they include a head assembly with a dam, a spillway and a water intake, a station assembly with a pressure basin that completes the supply diversion, pipelines supplying water to the turbines, and a hydroelectric power station building and the previously mentioned diversion elements.

Rice. 2. Run-of-river low-pressure hydroelectric complex with a hydroelectric power station and a shipping lock

In Fig. Figure 3 shows a hydroelectric power station with a short diversion canal on a mountain river. The head unit includes a concrete spillway dam, a water intake with a sedimentation tank. The station unit includes a pressure basin and an idle spillway. In Fig. 9 shows, partially in section, an underground hydroelectric power station with tunnel diversion. A high spillway dam, a deep water intake, as well as a surge tank at the end of the pressure inlet part of the diversion are visible.

Rice. 3. Hydroelectric power station with a diversion canal

If there is a dam, the hydroelectric complex must include spillways, as well as water outlets necessary for navigation. Both of these functions are often combined in one building. As a result of the construction of the dam, a drop (level difference) arises between the pools, to overcome which ships both going upstream and going downstream need navigation facilities (locks, ship lifts. Often, a port is built next to the waterworks with a water area protected from storm waves, berths, and a backwater for wintering ships.

The approach channels to the navigation facility, upstream and downstream, form a kind of diversion along which ships move, but little water flows, only for filling and emptying the lock chamber during the process of locking ships. Sometimes these canals acquire a considerable length if it is necessary to bypass a section of the river that is inconvenient for navigation - to straighten a sharp bend, to bypass rapids. Long canals with many locks connect different rivers with each other.

The use of water resources for irrigating agricultural lands and watering arid areas requires the construction of its own complexes of hydraulic structures and imposes its own requirements for regulating river flow. The area of irrigated land is usually very large, and the hydraulic structures located on it are so numerous that their complex cannot be called a hydraulic system; they are called an irrigation system. Part of the structures, compactly located on the used river, as part of a dam that forms a reservoir to regulate the flow of the river, a spillway to pass the flood, a water intake and a sedimentation tank for sedimentation from water taken for irrigation, is called the head unit of the irrigation system.

From the head node to the irrigated lands, water is supplied by a main water pipeline, most often a canal. Its length is measured in tens and hundreds of kilometers; along the way, distributors branch off from it, and sprinklers branch off from them. Unused residual water from the fields is collected by collectors and discharged into the watercourse. If part of the irrigated land is located above the water level in the main canal, water for these lands is supplied by pumping stations. On the irrigation network itself there are regulators, differentials, discharge structures, etc.

Drainage systems in areas of excessive soil moisture and widespread swamps naturally do not require the construction of dams. The complex of structures of these systems includes drainages, small and large canals, various structures on the drainage network; Corrective work is carried out on watercourses (straightening, clearing, deepening, coastal dams). The drainage system can be gravity-fed, however, if the terrain is too flat, pumping stations may be required on the network and to pump water into the watercourse.

Integrated water supply and sewerage systems are very complex and varied. The variety depends mainly on the type of water consumer - municipal or industrial water supply. Many industries require a continuous supply of large volumes of water, these include, for example, pulp and paper, metallurgical, chemical, thermal (and nuclear) power plants (for cooling condensers). Before the remaining part of this water, changed in its quality (wastewater), is discharged into a watercourse or returned to production (recycled water supply), it must be purified, disinfected, cooled, etc. As part of an integrated water supply and wastewater system, in addition to the head unit of structures on the river and the network of water pipelines at the consumer, there are pumping stations and a system for purifying water taken from the watercourse, as well as a more complex system for purifying water removed from the consumer.

3. Reservoirs

A reservoir is an artificial reservoir of significant capacity, usually formed in a river valley by water-retaining structures to regulate its flow and further use in the national economy. In table 1 shows the largest reservoirs in the world.

Table 1. Largest reservoirs in the world

The following main elements and zones are distinguished in the reservoir (Fig. 4).

Rice. 4. Main elements and zones of the reservoir. Main elements of the regime: 1 - low water level up to backwater; 2 - flood level up to backwater; 3 - normal retaining level; 4 - high water level under backwater conditions

The throughput capacity of a waterworks complex (its turbines, spillway spans, bottom holes, sluices) is limited for economic and, less often, technical reasons. Therefore, when a reservoir flows at a very rare frequency (once every hundred, thousand, or even ten thousand years), the hydraulic system is not able to pass the entire mass of water flowing along the river. In these cases, the water levels throughout the reservoir and at the dam rise, sometimes increasing its volume by a significant amount; simultaneously increases throughput waterworks Such a rise in level above the FSL during the period of high floods of rare frequency is called forcing the reservoir level, and the level itself is called forced retaining water (FRU). On reservoirs used for water transport or timber rafting, the level drawdown during the navigation period is limited to the level at which river fleet due to the conditions of the depths, it can continue normal operation. This level, located between the NPU and the UMO, is called the navigation response level (NS). Water levels, especially at NPU and FPU, at the dam, in the middle and upper zones reservoirs are not the same. If the level of the dam corresponds to the NSL mark, then as it moves away from it it increases, first by centimeters, and then by tens of centimeters. This phenomenon is called the backwater curve.

In addition to the great and undoubted benefits that reservoirs bring, after they are filled there are associated, often Negative consequences. These include the following. The greatest damage to the national economy comes from constant flooding of territories with settlements, industrial enterprises, agricultural lands, forests, mineral resources, railways and roads, communication and power lines, archaeological and historical monuments and other objects. By permanently flooded we mean areas located below the normal retaining level. Temporary flooding of areas located on the banks of reservoirs ranging from normal to forced backwater levels also causes damage, but occurs rarely (once every 100 - 10,000 years).

An increase in the groundwater level in the area adjacent to the reservoir leads to its flooding - swamping, flooding of underground structures and communications, which is also unprofitable.

Reshaping (reworking) of the banks of reservoirs by waves and currents can lead to the destruction of large areas of useful, developed territory. Landslide processes occur or become more active along the banks of reservoirs. The conditions for navigation and timber rafting on the river change radically, the river turns into a lake, depths increase, speeds decrease. The underbridge dimensions required for water transport are reduced.

The winter regime of the river changes greatly, the ice cover on the reservoir lengthens, and the sludge disappears, if there was any. Turbidity decreases as sediment settles into the reservoir.

Among the measures to compensate for damage caused by flooding and flooding of lands, cities, workers' settlements, collective farm estates, as well as industrial enterprises are relocated and restored to new non-flooded places. Individual sections of roads are moved, their surface is expanded, embankment slopes are strengthened, etc. They move or protect historical and cultural monuments, and if this is not possible, they study and describe them. They raise bridge spans and rebuild bridge crossings. River boats are being replaced by lake fleets, and mole rafting is being replaced by towing rafts. They carry out deforestation and forest clearing of the reservoir area. Complete the development of mineral resources (for example, coal, ore, building materials etc.) or provide the possibility of their subsequent development in the presence of a reservoir. Sometimes it turns out to be economically feasible instead of removing economic facilities and settlements from the reservoir flood zone, implement engineering protection measures.

The complex of hydraulic engineering and reclamation measures, united under the name engineering protection, includes diking or fencing of objects and valuable lands, draining flooded or embanked areas using drainage and pumping out water, strengthening the banks in certain sections of the reservoir, etc.

4. Dams

A dam is a structure that blocks a watercourse, which backs up water to a level higher than the domestic level and thus concentrates in one place a convenient pressure for use, i.e., the difference in water levels in front and behind the dam. The dam occupies an important place in any pressure hydraulic system.

Dams are built in different climatic and natural conditions - in northern latitudes and in permafrost areas, as well as in the south, in tropical and subtropical zones, with high positive temperatures. Their location includes high-water plain rivers flowing in channels composed of non-rocky soils - sand, sandy loam, loam and clay, as well as mountain rivers flowing in deep rocky gorges, where strong earthquakes often occur. The variety of natural conditions, purposes for creating dams, the scale and technical equipment of construction has led to a variety of types and designs. Like other structures, dams can be classified according to many criteria, for example, by height, the material from which they are built, the ability to pass water, the nature of their work as retaining structures, etc.

Hydraulic water-retaining structures, which include dams, perceive forces of different origin, nature and duration, the total impact of which is much greater and more complex than the impact of forces on buildings and structures of industrial and civil type.

To understand the operating conditions of water-retaining structures, consider the diagram of a concrete dam with the main loads acting on it. Like all extended concrete structures, the dam is cut into sections with seams that allow the sections to freely deform under temperature influences, shrinkage and precipitation, which prevents the formation of cracks. The following forces act on each section of the dam with length L, height H and base width B.

The weight of the dam section G is determined by its geometric dimensions and the specific gravity of the concrete g=rґg (as is known, the specific gravity of a substance is equal to the product of its density and the acceleration of gravity).

Rice. 5. Transverse profiles of modern dams in comparison with the silhouettes of other structures (dimensions in meters): 1 - Dnieper; 2 - Bukhtarminskaya; 3 - Krasnoyarsk; 4 - Bratskaya; 5 - Charvakskaya; 6 - pyramid of Cheops; 7 - Toktogul; 8 - Chirkeyskaya; 9 - Sayano-Shushenskaya; 10 - Usoi dam; 11 - Nurek; 12 - Moscow State University; 13- Ingurskaya

The pressure of filtered water on the base of the dam arises due to the underground flow of water flowing under pressure through the pores and cracks in the soil of the dam base from the upper tail to the lower one. The approximate value of this force, called back pressure, is equal to:

U=ґgBL,

where H1, H2 are the water depths in the pools; g is the specific gravity of water; a is a reduction factor that takes into account the influence of anti-seepage devices and drainage at the base of the dam.

The hydrostatic water pressure from the upper and lower pools is determined by the formulas:

W1=gH12L/2; W2 =gH22L/2.

The forces listed above belong to the category of the most important and constantly operating. Besides them, in necessary cases special formulas take into account the dynamic pressure of waves, the pressure of ice, sediment deposited in the reservoir, as well as seismic forces. Uneven temperature fluctuations have an additional effect on the strength of a concrete dam. Cooling of the dam surfaces causes tensile stresses in them, and cracks can form in concrete that weakly resists them. Under the conditions of the listed forces and water pressure, the dam must be strong, shear-resistant and waterproof (this requirement also applies to its foundation). In addition, the dam must be economical, i.e. Of all the options that satisfy the mentioned requirements, the option characterized by a minimum cost should be selected.

A special place in hydraulic engineering is occupied by issues related to the filtration of water from the upstream to the downstream. This phenomenon is inevitable, and the task of hydraulic engineering is to predict and organize it, and to prevent dangerous or unprofitable consequences with the help of engineering measures. The paths of filtration currents can be: the body of the structure, even if it is built of concrete; the foundation of a structure, especially when it is non-rocky or fractured rock; banks in places where pressure structures adjoin them. Harmful consequences filtration are unproductive losses of water from reservoirs, which are therefore not used for national economic purposes, back pressure, which reduces the degree of stability of the pressure structure, and filtration disturbances or deformations of the body of an earth dam or non-rock foundation, in particular, in the form of suffusion or uplift.

Suffusion is usually called the removal of small particles by filtration flow through the pores between more large particles; it occurs in non-cohesive (loose) soils - heterogeneous sandy, sandy-gravel. With chemical suffusion, salts located in rocks are dissolved. An outflow is the removal by an underground flow, filtering from under a pressure structure into the downstream, of significant volumes of foundation soil consisting of cohesive rocks, such as loams, clays, etc.

To ensure normal operation of the structure and eliminate hazardous phenomena, a rational underground circuit is provided when designing the structure (Fig. 6). This is achieved by increasing the filtration path under the structure, creating a waterproof coating in the upper pool (downstream) and a powerful water reservoir in the lower pool, laying sheet piles or other curtains, teeth or other measures.

Rice. 6. Diagram of a dam on a filter base (according to S.N. Maksimov, 1974): 1 - dam body, 2 - water body, 3 - apron, 4 - down, 5 - flow lines, 6 - sheet piles

Dams made of soil materials.

An ancient type of pressure hydraulic structures are dams made of soil materials. Depending on the soils used, dams can be homogeneous or heterogeneous; in the transverse profile, the body of the latter consists of several types of soils. To build a homogeneous soil dam, various low-permeable soils are used - sand, moraine, loess, sandy loam, loam, etc. In terms of the design of the dam and its connection with the foundation, this is the simplest type of pressure structure.

Heterogeneous soil dams, in turn, are divided into dams with a screen of low-permeability soil, laid on the side of the upstream slope of the dam, and dams with a core, in which low-permeability soil is located in the middle of the dam profile. Instead of a soil core, non-soil diaphragms made of asphalt concrete, reinforced concrete, steel, polymers, etc. can be used. Screens can also be made from the specified non-soil materials.

Depending on the method of carrying out the work, soil dams can be either bulk dams, with mechanical compaction of the poured soil, or alluvial dams, built using hydromechanization means; the latter method of constructing earth dams, subject to appropriate conditions (supply of water, energy and equipment, the presence of a suitable soil composition, etc.), is characterized by high productivity, reaching up to 200 thousand m3/day.

Rock-and-earth dams are built in the main part of the volume from rock fill; their waterproofness is achieved by constructing a screen or core, laid from low-permeability soils (loams, etc.). Between the stone and the fine-grained soil, reverse filters are installed - transitional layers of sand and gravel with increasing coarseness towards the stone to prevent suffusion of the soil of the anti-filtration devices.

Such dams are widely used in high-pressure hydraulic structures on mountain rivers. Thus, the height of the Nurek hydroelectric power station dam on the river. Vakhshe is 300 m.

Their advantage, compared to other types of dams, is the use of stone and soil available at the construction site, the possibility of extensive mechanization of the main types of work (stone casting and soil filling), as well as sufficient seismic resistance. Compared to other types of earth dams, rock-earth dams are distinguished by greater slope steepness, i.e. less amount of materials.

The small width of the low-permeability contact between the rock-earth dam and the foundation complicates the design of their waterproof interface. In non-rocky soils, it is necessary to drive a sheet piling row or lay a concrete spur, and in rocky soils, a cement curtain is installed by injecting cement mortar through drilled wells into rock cracks. Such connections prevent dangerous filtration phenomena at the base of pressure structures.

Rockfill dams are erected by throwing or pouring stone, and their water resistance is ensured by a screen on the upstream slope or a diaphragm in the middle of the profile, constructed from non-soil materials (reinforced concrete, wood, asphalt concrete, steel, plastics, etc.). Stone dams are built from dry stone masonry, which also requires the installation of screens, or from stone masonry with mortar. These dams are rarely built nowadays.

Dams made of artificial materials.

Wooden dams are one of the oldest types of pressure structures, dating back many hundreds of years. In these dams, the main loads are carried by wooden elements, and their stability against shearing and floating is ensured by securing wooden structures in the base (for example, driving piles) or loading them with ballast from stone or soil (in row structures). Wooden dams are built for low heads, from 2 to 20 m.

Fabric dams began to be built relatively recently due to the advent of durable, waterproof synthetic materials. The main structural elements of fabric dams are the shell itself, filled with water or air and acting as a gate (weir), anchor devices for attaching the shell to the concrete flute, a piping system and pumping or fan equipment for filling and emptying the shell. The scope of application of fabric dams rarely goes beyond the head limit of 5 m.

Concrete dams are widely used in hydraulic engineering. They are built in various natural conditions and allow the overflow of water through special spans on their crest (spillover dams), which is impossible or irrational in dams made of soil materials. Their structural forms are very different, which depends on many factors. The highest height of the concrete gravity-type dam Grand Dixance (Switzerland) is 284 m. In Russia, the Sayano-Shushenskaya dam of the arch-gravity type was erected on the Yenisei with a height of 240 m. The dam has a rocky foundation. The spillway dams of the Svirsky and Volzhsky cascades were built on a non-rock foundation in difficult geological conditions. Lightweight concrete dams appeared later than massive ones and have a relatively small distribution in Russia. By design, concrete dams are divided into three types: gravity, arch and buttress. The most famous type of these dams are buttress dams. Their advantage over massive ones is the smaller volume of concrete work. At the same time, they require more durable concrete and reinforcement with reinforcement.

Gravity dams, when subjected to the main forces of hydrostatic pressure, provide sufficient shear resistance, mainly due to their large dead weight. In order to combat water filtration, cementation curtains are installed at the base of the dam (in rocky foundations), and sheet pile rows are driven in (in non-rocky foundations). To increase the stability of the dam, drainage is organized, cavities are installed that reduce back pressure, and other measures are taken.

Arch dams are curved in plan with a convexity towards the upper pool; they resist the action of hydrostatic pressure and other horizontal shear loads mainly due to their emphasis on the banks of the gorge (or abutments). When constructing arch dams, a mandatory requirement is the presence of sufficiently strong and low-yield rocks in the coastal areas. These dams, like gravity dams, do not require a significant weight of concrete masonry; they are more economical than gravity dams. The radii of curvature of their arched elements increase from bottom to top.

Buttress dams consist of a number of buttresses, the shape of which in the side façade is close to a trapezoid, located at a certain distance from each other; the buttresses support the pressure ceilings, which absorb the loads acting from the upstream side. The bridge spans rest on the buttresses on top. In turn, the buttresses transfer the load to the base. The most well-known types of buttress dams are: massive buttress dams, with flat ceilings, and multi-arch dams. Buttress dams can be either blind or spillway. They are built on rocky and non-rocky soils; in the latter case, they have an additional structural element in the form of a foundation slab, the purpose of which is to reduce stress in the foundation soil. To give greater seismic resistance to buttresses under transverse seismic conditions (across the river), they are sometimes connected to each other by massive beams.

A feature of buttress dams is the increased width at the base and the slope of the top face, which leads to the fact that a significant vertical component of water pressure is transferred to the latter, pressing the dam to the base and providing it with stability against shear, despite the reduced weight. The back pressure in such dams is less than in massive gravity dams.

Buttress dams require smaller volumes of concrete than gravity dams, however, the costs of improving the quality of concrete, reinforcement and complicating the work make them quite close to each other in terms of economic indicators. The highest buttress (multi-arch) dam, Daniel-Johnson, 215 m high, was built in Canada.

5. Spillways

As part of the hydroelectric complex, in addition to the blind dam, great importance have spillways, i.e. devices for discharging excess flood waters or passing flows for other purposes. There are several different solutions for the location of spillways in a waterworks.

Spillway spans can be constructed at the crest of a concrete dam in the riverbed or on a river floodplain; then the structure will take the form of a spillway dam. A spillway can be constructed independently of the dam in the form of a special structure located on the coastal slope and therefore called a coastal spillway.

Both in the dam body and on the bank slope, spillway openings can be placed close to the dam crest mark or deep below the headwater level. The first are called surface, the second - deep or bottom spillways.

Surface spans of spillway dams can be open (without gates), but usually they have gates that regulate the upstream water level. To prevent the reservoir from overflowing, the gates are opened partially or completely, preventing the water level from rising above the normal retaining level (NLV). To improve the conditions for the passage of water through the dam, its crest is given a smooth, rounded outline, which then turns into a steeply falling surface, ending near the tailwater level with another reverse rounding, directing the flow into the river bed. The entire length of the spillway front is divided into a number of spans using bulls. Bulls, in addition, perceive water pressure from the gates, and also serve as supports for bridges intended to service lifting mechanisms and gates and transport connections between the banks.

The water released through the dam has a large supply of potential energy, which turns into kinetic energy. The fight against the destructive energy of the flow discharged through the dam is carried out in various ways. Behind the spillway dam, energy absorbers are installed on a massive concrete slab in the form of separate concrete masses - checkers, piers or reinforced concrete beams. Sometimes, in the downstream of a spillway dam, a surface regime is organized by installing a ledge and toe in the lower part of the spillway, breaking off from which at a higher speed, the flow concentrates at the surface, and a roller with moderate reverse velocities at the bottom is formed under it.

Behind spillway dams, which have non-rock foundations, an apron is made behind the water holes - a reinforced permeable section of the river bed.

Typically, on the shore, spillways are located in waterworks with dams made of soil materials that do not allow water flows to pass through their crest, as well as in waterworks with concrete dams in narrow gorges, where the channel is occupied by a hydroelectric power station building near the dam. Their types are very diverse. The most commonly used are surface spillways, in which the discharge flows along the surface of the bank in an open excavation. They are located on one or two banks, often next to the dam, and have the following components: an inlet canal, the spillway itself with spillway spans, bulls and gates (or automatic action without gates), an outlet canal in the form of a high-flow or stepped drop (used rarely). The coastal spillways are completed with water trenching devices, similar to those installed in the downstream of spillway dams - a water trench well.

If local conditions prevent the routing of the outlet channel, then it can be replaced with an outlet tunnel; This will result in a tunnel-type coastal spillway. Tunnel coastal spillways have the following components: an inlet channel located at high elevations of the coastal slope in the upper pool, the spillway itself with gates, and an outlet tunnel ending with a section of the canal and a water dispenser.

Deep and bottom spillways are located at elevations close to the bottom of the watercourse on which the hydraulic system is being built. They are arranged for the following purposes: to pass river flow during the construction of a dam in the riverbed (construction spillways), and in some cases to pass all or part of the discharge flow. Their main varieties are tunnel and tubular spillways. Spillway tunnels are located in rocky coastal massifs, bypassing the dam, their length is several hundred meters, the cross-sectional dimensions are determined by the flow rate. The cross-sectional shape of construction spillways is usually horseshoe-shaped. The remaining tunnels, operating under high pressure, have a circular cross-section.

Tubular spillways are located in the hydroelectric complex depending on the type of dam. If the dam is concrete (gravity, buttress or arch), then the spillways are pipes that cut through its body from the upstream to the downstream and are equipped with gates. If the dam is ground, then tubular drains are installed under the dam, deepening them into the base. They are a tower from which steel or reinforced concrete pipes of round or rectangular cross-section originate, depending on the pressure. They can be single or assembled into a kind of “batteries”, depending on consumption. Gates and control mechanisms are placed in the inlet and outlet parts of the pipes.

Gates and lifts. The main gates serve to regulate discharge flows and water levels in the upper pool, as well as to allow, in some cases, the passage of forest, ice, litter, and sediment. They can completely or partially cover culverts. The design of the gates depends on their location; gates of surface holes, often large, perceive relatively low hydrostatic pressure; valves of deep holes, which have significantly smaller dimensions, experience high hydrostatic pressure. Gates are most often made of steel, for small pressures and spans of blocked holes - from wood, in low-pressure non-critical structures with large spans - from fabric materials (fabric dams). The most widely used valves in hydraulic structures are flat valves, which are metal structure in the form of a shield moving in the vertical grooves of the bulls and abutments. The components of a flat gate are: a waterproof lining that absorbs the pressure of the upstream water, then a system of beams, trusses and support structures that roll or slide along special rails embedded in grooves. The mass of the moving part of the gates is quite significant; at large heights and spans it exceeds 100 tons, which requires powerful lifting mechanisms. To reduce the lifting force of the mechanisms, segmental valves are used, which, when raising and lowering them, rotate around hinges embedded in the bulls and abutments. Such valves are also widely used, but their cost exceeds the cost of flat valves.

6. Water intakes

waterworks dam plain reservoir

Purpose of the water intake. Water intakes are parts of water intake structures, the main purpose of which is to collect water from a watercourse (river, canal) or reservoir (lake, reservoir); the action for which they are intended can be called water intake.

The consumer usually regulates the water flow. Water intake must be ensured at any retaining level - from normal (NPL) to the lowest - dead level volume (ULO).

The functions of the water intake structure include purifying water from impurities and foreign bodies.

Water intake structures. The design and equipment of the water intake largely depend on the type of hydraulic unit and the type of water pipeline - pressure or non-pressure. Therefore, a description of the designs and equipment of water intakes and their operation is only possible separately for each type. The dimensions of the water intake are characterized by the dimensions of its inlet section, where debris-retaining gratings are located (often called debris-retaining grates). To facilitate cleaning of the screens and reduce pressure losses on the screens, the flow velocity at the inlet is taken to be no more than 1.0 m/s. The inlet area of large turbines is measured in hundreds of square meters.

A water intake of this type, individual for each turbine, is a rectangular hole in the dam mass, gradually narrowing and turning into a circular section of the turbine conduit.

The upper part of the entrance is closed by a reinforced concrete wall - a visor, lowered below the ULV. The visor absorbs ice pressure and traps floating objects. In front of the entrance to the water intake, a grid 1 of strip steel rods is installed to retain debris suspended in the water that could damage the turbine. During operation, the debris that accumulates at the water inlet and on the grate is removed with a mechanical rake or grab, since if the grate becomes clogged, its resistance to water flow will increase significantly.

Behind the grate, grooves are made in the bulls to install the gate 3 and stop the water supply to the turbine conduit. In order to be able to maintain and repair the high-speed shutter, grooves 2 are arranged in front of it for the repair shutter. You can get to the valve for inspection and repair through inspection hatch 6. The repair valve is simpler, it is not required to operate quickly, it is lowered not into the stream, but into calm water. An air duct 7 is installed behind the valve - a pipe for supplying air to the turbine water duct, replacing the water leaving through the turbine in the event of the water intake being closed by an emergency repair valve. For ease of operation, a building equipped with an overhead assembly crane is erected above the water intake. In favorable climatic conditions, the building is not built and a portal-type assembly crane is used.

The main valve regulates water flow in accordance with the water consumption schedule. The movement of the shutter is carried out using a hydraulic drive.

In case of small fluctuations in the level of the upper pool, the water intake structure is located at high elevations of the coast; this is the so-called surface coastal water intake. With a wide range of operational levels of the reservoir, it is necessary to install a deep coastal water intake, located slightly below the ULV.

7. Water pipelines

Purpose of water pipelines. Water that enters the water intake and is cleared of impurities must be left to the consumer in accordance with the consumption schedule. One of the main requirements for water pipelines (pressure and non-pressure) is the waterproofness of their walls. Water should not be lost along the way, and this loss should not make the surrounding area swampy. For a hydroelectric power station, it is also necessary that the potential energy of the flow be lost as little as possible along the path, and that the slope of its free or piezometric surface be small. To do this, the walls of the conduit must be smooth and characterized by low resistance to flow. Smooth walls are needed by water pipelines and irrigation systems and water supply systems - the higher the water is supplied, the easier it is to ensure its gravity supply to consumers, the less energy is spent on operating pumping stations. Only for shipping canals the roughness of the walls does not matter, since the velocities in them are small or equal to zero.

The walls of conduits should not be eroded by current speeds and waves (waves arise, for example, when ships move along canals).

The dimensions of the cross-section of the water pipeline are determined on the basis of technical and economic calculations. The type and design of the water pipeline are also determined on the basis of technical and economic comparisons. Depending on the purpose of the water pipeline, its size, natural conditions and conditions of construction and operation, channels, trays, pipelines, and tunnels can be used as a water pipeline. The first two types are non-pressure, the third is pressure; the tunnel can be either pressure or non-pressure (if it is not filled to the top with water). Often the optimal solution is achieved by sequentially combining different types of water pipeline sections.

The simplest and cheapest type of conduit is usually a canal. Channels are common in all areas of hydraulic engineering. It is advisable to lay the canal route on the plan so that the water in it is in the recess and the height of the dams is small. The cross-sectional shape is trapezoidal (sometimes of a more complex shape), the steepness of the slopes is determined by their stability; the soil should not slide.

In rocky soil, the cross-section of the channel approaches rectangular. The cross-sectional width of the channel is greater than its depth in order to reduce water losses due to filtration from the channel, increase the flow speed and reduce flow resistance, i.e. The slope of the surface, the bottom and slopes of the canal are covered with lining, most often concrete or reinforced concrete. A layer of coarse soil (gravel) is placed under the cladding as drainage.

A tunnel is the most expensive type of conduit per unit of length. If the tunnel is laid in weak, non-rocky soils, then its cost especially increases. In this regard, it can be preferred to surface types of diversion only if it is significantly shorter, allows the route to be straightened, or if the coastal slope along which the route can be laid is unsuitable for surface diversion - very rugged terrain, high steepness, landslides, avalanches .

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Hydraulic structures are designed. Hydraulic structures: types, classification, operating rules, safety requirements