Deep gates transmitting water pressure to the structure through the support-running parts. flat closures

When carrying out emergency or planned work, it often becomes necessary to free the channel from the contents (usually liquid). For these purposes, the water supply is stopped or its flow in the canal is suspended. When the manipulations come to an end, the space is gradually filled again.

To ensure a reliable blocking of the passage of contents, it is recommended to use a shield shutter. It blocks the flow, due to which the liquid level begins to fall. As a result, the channel remains empty, available for service.

Modern shutters are characterized by reliability and optimal quality of materials, a sufficient period of use. Their production is carefully planned taking into account the established safety requirements for products of this type. The deep shield shutter is installed in the galleries of locks, mines, treatment facilities of water supply systems, chambers of gravity sewer networks, sewer tunnel collectors, in the receiving chambers of pumping sewer stations and other hydraulic structures.

TYPICAL DIMENSIONS OF DEEP PANEL VALVES UP TO 10 M. W. ST

The deep shield gate is indispensable if it is necessary to install regulating and shut-off products, for partial passage of the liquid contained in the channel. It makes it possible to block holes of various geometric shapes. Depth shutter is of two types:

• shutter flat sliding;
• wheel gate flat.

The sealing of these structures is carried out immediately on four sides: along two vertical guides, along the threshold, along the visor beam. They easily adapt to any building frequent. As for the design of deep installations, they can be produced with a bypass - a special bypass device that helps to equalize the water levels on both sides of the gate. The lifting of the latter is carried out in a non-pressure mode (the wire is selected taking into account the weight of the shield gate and possible friction in the supporting parts). The design of the shield gate adapts to any building part.

Shutter shield flat wheel

The flat depth gate is usually made from corrosion-resistant and structural steel grades.

The installation of the shutter mechanism has its own characteristics. So, first you need to check that the building structure fully complies with all the prepared drawings, on which the literacy and reliability of the planned installation work depends. If the slightest deviations are found, it is necessary to recalculate and adjust the existing schemes. It is important that valve assemblies supplied to the installation be free of sand, dirt, snow, ice, protective grease and paint.

Shield valves are available in two versions:

• With electric drive;
• With manual drive.

There are several types of shield gates:

• Locks for installation in the channel without pouring concrete;
• Locks for installation in the channel with concrete pouring;
• Shutters for camera wall mounting;
• Control gates with spillway;
• Sliding gates, lifted by a lifting mechanism;
• locks are flat wheel, for installation in a gate.

For mining and processing and metallurgical enterprises, pin gates according to project 827.10-05.003.000. These shutters serve as a screen for overlapping iron and other pellets with a size of 5-16 mm from the hopper to the conveyor.

The main components of the shutter are:

1. Frame;
2. Shield (in the case of wheeled ones);
3. Drive shaft;
4. Actuating mechanism for manual or electric drive.

The frame is mostly welded from a corner. Assembly takes place in several stages:

1. A corner of the required length is cut, a gap is set between the two parts of the frame, which will subsequently be the guide of the shield;
2. All four parts of the frame are set diagonally on a flat surface and welded into a single structure;
3. A shield is cut out, stiffeners are mounted on it, sealing rubber (ordinary or oil and petrol resistant (mbs) depending on the working environment of the installation site), the lower part of the actuator is sharpened and installed;
4. The upper part of the actuator is sharpened, milled and assembled, after which the shield is installed in the frame and the final assembly and painting of the shutter takes place.

Installation is carried out in a specially prepared strobe to the wall, either for pouring or without pouring concrete.

• Series 3.901-12
• Series 3.820.2-37
• Series 3.820.2-47
• Series 3.820.2-43
• Series 3.820.2-58
• Series 3.820.2-63
• Series 7.820-4
• Series 7.820-6

Closures are flat overflow.

Flat overflow valves are designed to maintain a given level of the medium in the surface tank.

Overflow gates allow excess through the top of the shield, or empty it completely after opening.

Flat gates are often used on irrigation systems, dams of fire reservoirs, artificial ponds and lakes, so that they do not overflow, and the water does not go beyond the boundaries of the reservoir during spring floods and heavy rains. Such gates often perform the function of repair and emergency repair.

The name of flat valves comes from their classification by design. This is the simplest and most common type. To facilitate maneuvering, overflowing water and dropping objects floating on top, flat gates are sometimes divided in height into 2 parts (the so-called double gate) with an overlapping area of ​​​​240 m2.

The design consists of:

• A flat shield rolling up and down the skids;
• Corner frame, which is connected to sheet sheathing 4-5 mm thick (usually steel).
• A frame consisting of vertical posts, horizontal beams - the main crossbars - and auxiliary beams. For small gates, it is advisable to use a multi-bar scheme, which makes it possible to get by with smaller groove sizes and rolling profiles. For large gates, a two-bar scheme will be more economical. The aspect ratio of the beam cage is usually taken as 1:1 or 1:2.
• Stiffness ties (in gates large sizes), giving rigidity and spatial invariability of the structure;
• Gate valves having a round or rectangular shape and operating under pressure up to 100-200 m and more. Gate valves move along sliding, sometimes roller bearings. The bypass pipe connects the sections of the conduit in front of and behind the valve and achieves the movement of the latter in non-pressure conditions.

If speed is needed, the valves are controlled by electric and hydraulic actuators. If the efficiency of control is not critical - with the help of cranes, usually gantry ones.

The most common documentation on which these valves are produced:

• Series 3.820.2-53
• Series 3.820.2-57

Repair stoppers (sandors).

Repair stopper (sandor) is designed to block channels of different dimensions and bandwidth, depending on the design, they can work in various weather conditions (with low temperatures heaters are installed in the shandor). They can replace both tray gates (with 3-side seal) and depth gates (with 4-side seal). The main difference between repair stop valves from tray, overflow and depth gates is the fact that repair gates are operated manually by third-party mechanisms that are not related to the design of the gate (truck crane, beam crane, etc.). Most of the repair stop valves are installed in place of trash grates, in the same frame, for the period of repair of the blocked channel or pipe. In some cases, repair stopper valves are installed for permanent location at facilities where operations with their opening and closing are used extremely rarely, or the dimensions, loads and weight of the valve do not allow the use of valves of another class or their use is unprofitable.

Stop valves are mounted in the frame by pouring the channel into the strobe or by mounting to the wall on anchor bolts. Installation must be carried out by specially trained people, strictly according to the instructions specified in the manufacturer's passport. The main indicator during installation is the observance of the diagonals of the side and lower pillars of the shutter frame. Failure to comply with the diagonals and other installation instructions may lead to leakage of the gates, or to the impossibility of installing the repair stopper shield into the frame.

Tray shutters.

Tray gates are designed to shut off and control the level of the medium in channels, pipes and open trays.

Tray gates are used in systems of artificial irrigation of fields, reservoirs, fisheries, fire extinguishing systems, mining and processing and metallurgical enterprises, treatment facilities, and in the chemical industry. Side outlet tray valves are usually used in combination with chain or pin valves.

A trough gate is a closing mechanism consisting of a frame attached to a channel or wall by pouring concrete into a gate, attaching to a wall or channel wall using anchor bolts. consists of a frame, shield and actuator.

Tray gates block the channel by lowering the shield. the shield is lowered to the required height by means of an actuator. The shutter can perform both a regulating function and the function of a complete overlap, or vice versa, opening a channel.

The trough gate is designed and constructed to work with liquid media, both aggressive (sewage, etc.) and non-aggressive (in irrigation and water supply systems).

Depending on the size of the gate and the customer's needs, the gate can be controlled manually, by means of a handwheel or gearbox, as well as by various types of hydraulic and electric drives. The electric actuator is considered to be the best option for tray gates.

Flat valves are the most widely used. They are used both for basic and emergency repairs. They are made of steel (welded or cast) and reinforced concrete. Gate supports can be sliding, wheeled, roller or caterpillar; the blocked opening - rectangular, square or round.

Sliding support elements at low loads are made of wood, with an increase in load - from synthetic materials, as well as in the form of a strip of bronze, special alloys with the use of lubrication of the skids under pressure at especially high loads, which also protects the skids from corrosion. For examples of flat sliding gates, see fig. 20.1.

The use of reinforced concrete flat gates became possible with the advent of prestressed concrete. The large weight of reinforced concrete deep-seated gates can play a positive role, as it allows you to reduce or eliminate the load required to seat the gate on the threshold. Reinforced concrete deep sliding gates appeared in the late 50s in the form of experimental structures, the operation of which is very successful. For example, in the openings of the spillways of the Volzhsky building

Rice. 20.1 Flat slide welded emergency deep end valves:
a - multi-bar outlet gate 3x6 - 89 m; b- sectional shutter 6x14 - 60 m (section in the vertical plane); 1 - bronze seal; 2 - lignofoil skid (dimensions in mm)

hydroelectric complex, three reinforced concrete gates of different design were installed with a size of (b x h- H) 4.25 x 2.38 - 30.5 m. Consumption of metal in reinforced concrete gates is about half as compared to steel gates, the cost is lower by 30-40%. However, deep reinforced concrete gates have not received distribution.

Gates made of prestressed beams with adhesive joints have not yet been used, which, according to design studies, are promising.

Wheel gates require less lifting effort than sliding gates and are mainly used as emergency repairs. Their disadvantage is the difficulty of protecting the wheel bushings and bearing rollers from pollution and liming, therefore, in cases where the wheel bearings are constantly in the water with an open and closed hole, the use of wheel locks may not be appropriate.

Sectional wheel depth gates, as well as sliding gates, are used when closing openings developed in height requiring a large number of wheels or sliding bearings, in this case, the division of the shutter into sections provides work, the shutter without hanging individual supports due to uneven working paths and inaccuracies in the installation of supports.

On fig. 20.2 shows two sections of a deep six-section wheeled emergency gate with a size of 5x20-59 m of the water intake of the high-altitude Aswan dam. The running wheels are located on the consoles. Articulated connected; between the axles of the wheels combine sections, the rise and fall of which occur simultaneously.

Rice. 20.2 Flat wheel emergency closure:
a - view from the pressure side; b- side view

With a significant main hydrostatic load, it is not possible to place the number of wheels required from the strength conditions. In this case, instead of wheels, rollers are used, united by a frame (roller bearings) or a caterpillar (caterpillar bearings). In modern practice, caterpillar supports are used as more reliable ones (Fig. 20.3). loads on the contact support structure to abandon the metal tracks in the grooves. For maneuvering a gate with roller or caterpillar bearings, mechanisms of lower carrying capacity are required than with other types of bearings.

The position of the sealing circuit has a significant effect on the lifting force of a flat depth seal. With a sealing circuit,

Rice. 20.3 Flat caterpillar cast closure:. 1 - rollers; 2 - caterpillar; 3 - reverse wheel; 4 - rubber sealing element; 5 - reverse wheel buffer

located in the plane of the pressure face (Fig. 20.4, a), vertical components of forces atmospheric pressure R a acting on the shutter from above and below are practically balanced. With a sealing contour in the plane of the bottom face (Fig. 20.4, b) the force of water pressure in the shaft acts from above, from below - the force of water pressure, the direction of which depends on the opening of the shutter, with a closed hole it acts upwards, with a partially open one - upwards or downwards, depending on the outline of the bottom seal. The most favorable hydraulic conditions are created in cases where the flow is compressed before the gate, and behind the gate - separation from the walls, which is achieved by the device in front of the gate of the confusing section (Fig. 20.5, a). The compression of the jet facilitates the aeration of the separation zones, which is necessary to combat cavitation erosion. The separation of the flow from the bottom of the conduit behind the gate is provided by a ledge device. Separation of the flow from the walls behind the gate is achieved

Rice. 20.4 Deep seal seal position:
a- from the upper side; b- from the lower side; 1 - seal

Rice. 20.5 Options for the design of the conduit at the location of the gate:
a- confusing area in front of the shutter; b- separation of the flow from the walls due to the expansion of the conduit or the device of reflectors; 1 - aeration channels

Rice. 20.6 Flat gates of the spillway of HPP Mavoisin:
1 - overhead crane; 2, 3 - hydraulic drive of the main and emergency gates; 4 - aeration shaft; 5, 6 - main and emergency flat valves

also by expanding the conduit behind the gates or the device of reflectors (Fig. 20.5, b).

On fig. 20.6 shows the shutter chamber of the Mavoisin hydroelectric complex (Switzerland), located on the tunnel route. The area of ​​the openings to be covered is 5.4 m2 at a head of 200 m.

Flat valves have received more mass application in comparison with segment valves, because the cost of their manufacture is 10-15% lower than segment valves and installation is three times cheaper.

Depending on the size of the opening to be blocked, the purpose of the hydraulic structure and the conditions of its operation, various types of flat gates are used. More often used flat shutters single and sectional. The span structure of single flat gates consists of one panel.

They are used with a hole height of up to 14 m. Such gates do not allow water to overflow from above.

Sectional flat gates consist in height of several parts - sections, the movement of which can be carried out one by one and simultaneously - in a link.

For reclamation systems, single gates are usually used, and only in rare cases are double gates. The spans of such gates are small - 0.5-6 m. They are intended for use in hydraulic structures on canals of irrigation and drainage systems passing in earth lined and unlined channels and flumes, on structures with earthen dams and partially on outlets of a closed reclamation network .

Surface gates of reclamation systems (figure below) are used at heads up to 3 m, deep ones - at heads up to 12 m; they serve to maintain the water level in the upstream, regulate water flow or completely close the openings of hydraulic structures.

The main elements of the gate of reclamation systems

1 - sheathing; 2 - crossbars; 3 - support-end post;

4 - top harness; 5 - intermediate verticals

A flat shutter consists of a movable part (the shutter itself) and fixed parts (groove device). Move the shutter lifting mechanisms.

The movable part of flat gates of reclamation systems (small spans) consists of a casing installed on the pressure side, one or more crossbars, upper trim, support-end posts and intermediate verticals. Sheathing is made of sheet steel 4-6 mm thick, the rest of the elements, as a rule, are made of rolled metal (channels, corners, I-beams). Maneuvering of the gates is carried out by screw lifters.

Small-span gates can be considered a simplified version of large-span gates. Therefore, the purpose of the main elements, design and calculation are detailed below. hydraulic gates significant spans (more than 10 m).

The movable part of a flat gate with spans of more than 10 m consists of the following elements (figure below). Sheet steel sheathing, usually located on the pressure side of the gate, prevents the flow of water, directly perceives its pressure and transfers the latter to auxiliary beams, posts and crossbars. The beam cage consists of auxiliary beams and racks and transfers water pressure from the skin to the crossbars. Auxiliary beams are usually placed horizontally. The elements of the beam cage are made from rolled I-beams or channels. Rige-li - the main bearing elements of the shutter - transmit water pressure to the support-end posts. Depending on the length of the gate span and the height of the water pressure, the crossbars are made from rolled or composite beams. In rare cases, crossbars can be in the form of trusses. Support-end racks transmit horizontal and vertical pressures from crossbars and longitudinal braced trusses to the support-running parts and suspension devices. The support-end racks provide the mutual arrangement of the ends of the crossbars and serve to fix the support-running parts.

Basic elements and dimensions of a flat single surface gate

1 - sheathing; 2 - top harness; 3 - auxiliary beam; 4 - side wheel; 5 - back stop; 6 - crossbar; 7 - longitudinal connections; 8 - cross links; 9 - wheel support; 10 - support-end post; 11 - rack beam cells; 12 - holes in the lower crossbar of the valve operating in the flow at α ≤ 30°

Cross ties are vertical trusses, the belts of which are, on the one hand, racks of a beam cage, and on the other, racks of a longitudinal truss truss. The truss lattice is of the most diverse shape. At present, the cross-link lattice is often replaced with a continuous sheet - a diaphragm. Transverse braces must maintain the spatial invariability of the through parallelepiped formed by crossbars and longitudinal braces, and prevent it from twisting. In cases of uneven loading of individual crossbars, transverse braces equalize the load between them.

Longitudinal connections between the crossbars, located in the plane of the stretched belts, together with these belts form a vertical truss. On the side of the compressed chords, the role of longitudinal ties is performed by the sheathing, which, together with the elements of the beam cage, forms a hard disk. Longitudinal connections perceive the own weight of the shutter and other vertically acting loads, transferring them to the support-end posts. As a result, the mutual arrangement of crossbars remains unchanged, they also reduce vertical deformations (sagging) of horizontally located crossbars. Transverse and longitudinal connections ensure the operation of the shutter as a spatial structure.

The running parts and guides (figure below) are used to transfer water pressure to the fixed parts of the gate, to the mass of concrete of the structure and to move the gate. The seals close the gaps between the casing and the embedded parts of the shutter, preventing water from leaking around the casing.

The raising and lowering of gates of significant spans is most often carried out using gantry cranes.

The fixed parts of a flat gate (figure below) include the following elements: support-running parts for impellers, rollers, skids (working paths); support-running parts for reverse and side wheels or stops (reverse and side paths); embedded parts of vertical and horizontal seals; reinforcement of corners of concrete masonry and visor walls; valve heating devices. The elements of the fixed part of the shutter are located in the grooves.

Bearings and guiding devices of the flat valve

a - sliding support and reinforcement of the groove device; 6 - wheel support;

1 - sliding support; 2 - crossbar; 3 - side stop; 4 - working path (rail); 5 - reinforcement elements; 6 - facing the groove; 7 - support-end post;8 - wheel support; 9 - lateral vertical seal;

10 - side wheel; 11 - back stop

Flat gates can be one-, two- and multi-bar. Two-bar gates (see the figure above) are most often used in construction.

The concentration of efforts, and, consequently, materials in two powerful crossbars leads to simplicity of design, clarity of its static work, as well as to a decrease in the complexity of manufacturing and installation. The feasibility of using double-bar gates increases with an increase in the span. Single and multi-bar gates are used for small and medium spans, when it is possible to get by with crossbars from rolled beams. In gates of medium spans with a high pressure for crossbars, the same type of welded beams with a variable width of belts along the height of the gate are used. Multi-bar gates are used to cover deep holes.

Segment closures. Segmental gate (figure below) is a gate, the superstructure of which in cross section has the form of a segment and is attached to two supporting legs, rotating around a horizontal axis. Unlike flat valves, segment valves are used only as the main ones. Segmental valves are surface and immersed (deep). Surface valves cover openings with a span of up to 40 m at a height of up to 14 m, submerged ones are used for heads of more than 100 m. A segmental valve consists of movable and fixed parts.

The movable part includes a steel casing of a cylindrical shape, which directly perceives the pressure of the water and transmits it to the supporting beam cage. The beam cage, consisting of auxiliary beams and racks (with lattice diaphragms), transfers the load to the diaphragms and the main crossbars. Diaphragms (solid sheets or vertical transverse trusses) take the load from the beam cage and transfer it to the portals; diaphragms ensure the invariability of the shape of the cross section of the shutter. Portals, consisting of crossbars and legs, take all the pressure on the shutter and transfer it to the supporting parts. In addition to working in the horizontal plane from water pressure, the belts of the portal crossbars also work in the vertical plane - in the system of lifting (weight) trusses, of which they are belts. Lifting trusses, located on the non-pressure side of the gate, perceive its own weight, which is transferred to the end posts. On the pressure side, the role of the lifting truss is performed by the sheathing. Lifting trusses provide the spatial stability of the shutter.

The supporting trusses, which connect the branches of the legs of the portal into a single structure, transfer to the supporting part all the water pressures, part of the weight of the shutter and the reaction from the traction force that occurs during the lifting (lowering) of the shutter. The supporting parts transfer the water pressure and the weight of the valve to the support hinges and provide rotational movement of the valve when maneuvering it. The seals cover the gaps between the movable structure and the embedded parts.

The fixed part of the segmental gate includes: axes of support hinges that transmit water pressure and the weight of the gate through the embedded parts to the concrete of the structure; embedded parts for seals; reinforcement for fixing embedded parts in concrete; valve heating devices.

The shutter with the lifting mechanism is connected by a hanging device.

Basic elements of a segmented shutter

1 - lattice elements of the lifting farm; 2 - crossbars; 3 - sheathing; 4 - auxiliary beams; 5 - legs of the portal; b - diaphragm; 7 - elements of the supporting farm; 8 - guide wheel; 9 - seal; 10 - support part; 11 - support hinge

The most common surface segmental gates are gates with two equally loaded portals and with a skin outlined along an arc with a radius from a point coinciding with the center of rotation of the gate. Since the water pressure is directed to the pressure surface of the valve and, therefore, its resultant passes through the center of rotation, the operation of the lifting mechanism is limited only by moving the mass of the valve and overcoming friction in the support hinges and seals. This is the great advantage of segmental valves with a cylindrical surface. The axis of rotation of the surface segmental gate should be located above or at the level of the highest position of the free flow surface in the upstream to protect the supporting parts from damage by ice drift, sediment clogging and freezing.

The shutters are divided into six groups. The 1-4th groups include surface flat, segmental and similar main and emergency gates, gates of shipping locks and water galleries, submerged gates with a pressure of more than 10 m, repair gates; to the 5th group - building gates, to the 6th - other gates.

Depending on the valve group and the selected steel grade, the calculated resistances of the material and welded joints are determined. When determining the design resistances, the coefficient of operating conditions and the coefficient of transition to derivative resistances in bending, equal to 1.05, are taken into account, taking into account the possible limited development of plastic deformations. The design resistance of steels is given in the table below, of welded joints - in the table below.

Design resistance of steels, MPa

Note. The thickness of the shaped steel should be taken as the thickness of the flange.

1. The simplest circuit shutter. A conventional flat metal shutter is a metal supporting structure covered on the upper side with a waterproof sheathing made of sheet steel, arctilite or wood.

In the simplest case, the metal supporting structure is a beam cage.

From fig. 121.1 it can be seen that seals b and 7 are arranged along the contour of the shutter, blocking the gaps formed by the seals. 21.1. The simplest scheme of the usual is waiting for the gate and the concrete parts of the structure. Lifting forces are applied to the support posts 3, to which the water pressure is transmitted from the crossbars. When the shutter is raised, its support legs move along special fixed rails 9 embedded in the grooves. In order to avoid skew and lateral movement of the shutter at the support stacks, auxiliary support devices are sometimes provided in the form of reverse and side guide rollers.

To ensure the transfer of the own weight of the shutter to the support legs, as well as to obtain a sufficiently rigid structure, special connections are arranged. The crossbars are often placed at different distances from each other (from top to bottom at a smaller distance) in order to get them equally loaded with hydrostatic pressure, which increases downward. Similarly, in an effort to obtain, according to the calculation, the thickness of the steel sheathing at the top and bottom of the shutter is approximately the same, the dimensions of the cells of the bearing part of the shutter are increased upwards. With large hole widths, the crossbars are made in the form of through trusses.

On fig. 21.1 shows a simplified diagram of the so-called multi-bar shutter, now rarely used; these closures are economically viable only at relatively small ratios. At present, in the relationships commonly encountered, so-called double-bar flat closures are used almost exclusively.

2. Bearing part and casing of a two-bar flat gate. The supporting structure of a double-bar gate, consisting of various horizontal and vertical elements, as well as corresponding inclined braces, is a spatial truss operating in difficult conditions and not amenable to accurate static calculation. There are many various types such spatial trusses (used for different b and H). The general scheme of a two-bar gate is shown in fig. 21.2.

Crossbars. In order to obtain crossbars 2 equally loaded with hydrostatic pressure, and therefore of the same design and dimensions, they are often located at the same distance from the line of action of the hydrostatic pressure force P acting on the skin.

In the places where the crossbars adjoin the support posts 3, the sliding parts of the shutter are usually located. In order to ensure greater stability of the shutter, located on four support devices, the distance between the crossbars tends to be set as large as possible. With an increase in the size a, the height r decreases from the cantilever part of the shutter, which is not recommended to be set more than (0.4 ... 0.45). Generally speaking, the dimensions are specified taking into account: a) the type of support parts; b) the width of the steel sheets used to form the skin; c) breakdown of the metal structure of the shutter into mounting units.

When assigning the size a2, the condition regarding the distance d is maintained, this distance should be large enough so that when the shutter is raised, the water flowing from under the shutter does not hit (during the expansion of the jet) on the lower crossbar and does not create a vacuum under it; require, for example, that the angle φ shown in the figure be at least 30°, or consider that the dimension d must be at least (0.12 ... 0.15) N.

Crossbars are made: a) in the case of holes with a width of b 10 ... 15 m - in the form of solid beams (for example, an I-section, channels, etc.) with a height in the middle of the span; b) in the case of holes of greater width - in the form of through trusses, with the height of the trusses in the middle of the span. The height of the crossbars on the supports is reduced to (0.40 ... 0.65) h. The number of panels in a through farm is assigned to be even. When designing, they are interested not only in the strength of the shutter, but also in its possible deformations. It is believed that the rigidity of the crossbars should be large enough.

Transverse vertical farms are made through (see Fig. 21.2) or solid. In the presence of through crossbars, transverse vertical trusses are located in vertical planes passing through each node of the crossbar truss.

To the support posts 3 (see Fig. 21.2), the supporting parts of the shutter are attached. The ends of the crossbars are fixed in the support posts, and at these points the hydrostatic pressure from the crossbars is transferred to the support posts. The length of the support posts is equal to the height of the jam. There are support posts: single-walled (Fig. 21.3, a) and double-walled (Fig. 21.3.6) with a distance between the walls of at least 0.5 m. The height of the support posts should be equal to the height of the end part of the main crossbar 1 (Fig. 21.3).

Auxiliary crossbars 7 (see Fig. 21.2), in contrast to the main eigels, are located between vertical girders and 6. They are formed, for example, by channels.

Auxiliary racks 5 (see eis. 21.2) are not always provided. Assistance if available. spruce racks, their parts are placed between the auxiliary crossbars 7. They are formed, for example, by channels, corners, etc.

Sheathing 10 (see Fig. 21.2) covers the auxiliary crossbars and posts that form a beam cage. In the absence of auxiliary racks, the beam cage is formed by transverse vertical trusses and auxiliary crossbars. Sheathing is made from individual steel sheets, rarely arctilite or wood. The thickness of the steel sheathing resting on the beam cage and directly perceiving the hydrostatic pressure is set by calculation, and the resulting thickness is slightly increased (for example, by 1 mm), taking into account the possibility of rusting. To make the shutter rigid, the skin is made at least 8 ... 10 mm. Typically, the thickness of the steel sheathing is obtained equal to 8 ... 20 mm.

The dimensions (spans) of the beam cage to the bottom of the shutter are sometimes reduced so that the calculated thickness of the steel sheathing along the height of the shutter is the same.

Additional connections are provided to increase the rigidity of the metal structure, as well as to ensure the best transmission own weight of the shutter to the supporting posts, which perceive the lifting forces.

The connection of the metal elements of the shutter is currently carried out by welding.

Operating conditions of the shutter elements. Hydrostatic pressure acts from the upstream side directly on the skin. From the skin, this pressure is transferred to the beam cage (Fig. 21.4), which turns out to be formed only transversely. Distribution of the hydrostatic method The hydrostatic pressure between the auxiliary girders and the transverse vertical girders is distributed as shown in fig. 21.4. For example, hydrostatic pressure is transferred to the auxiliary bolt ab from the area of ​​the skin, shown by vertical shading (Fig. 21.4, a); therefore, this crossbar will be loaded with an unevenly distributed load (Fig. 21.4, b).

Along with this, the transverse vertical truss cd (Fig. 21.4, c) will perceive hydrostatic pressure from the plating side from the plating area shown by horizontal hatching (see Fig. 21.4, a); in addition, concentrated forces 5 will act on this farm at the points of attachment of auxiliary crossbars to it (see Fig. 21.4, c). In accordance with the scheme of forces transmitted from one gate element to another, it is necessary to identify the hydrostatic pressure load of all elements to be calculated (including the main crossbars). Additionally, take into account the own weight of the shutter, which is also transmitted to the support posts.

3. Basic running parts of conventional flat valves. Depending on the design of the supporting parts, there are metal flat sliding friction gates, wheeled, roller.

Sliding friction gates have a supporting part made of wood (Fig. 21.5, a), metal (Fig. 21.5.6) or wood-laminated plastic (chipboard) (Fig. 21.6).

In the case of small gates (see Fig. 21.5, a), a wooden beam is arranged throughout the entire height of the support post, and it can act as a side seal. Chipboard is made in the form of slabs assembled from birch plates (Fig. 21.0, a), impregnated with special resins and glued together with them heat treatment under high pressure. The chipboard friction surface should be formed by the ends of the wood fibers. As can be seen from fig. 21.6 arrange four separate runners, based on a fixed mortgage part in the form of a rail covered with a strip of stainless steel.

When sliding the running parts along the fixed rails - embedded parts - a friction force arises. The power of lifting mechanisms depends on the value of the coefficient. Distinguish between the coefficient of rest (at the moment of starting) and when moving. For sliding steel on steel: in the case of rest 0.5; in case of movement 0.15. When using chipboard, it decreases to 0.04.

In the case of weir gates, chipboard should not be used, since in the surface state this material can be crushed and destroyed.

Wheel gates are used to reduce the power of lifting mechanisms. To do this, wheels or wheeled carts are attached to the support posts, which must roll along the rail. In the case of a wheel gate, the resistance to movement is composed of: a) rolling friction of the wheel along the rail and b) sliding friction between the wheel and its axle; to reduce sliding friction, arrange roller bearings. Knowing the dimensions of the wheel and the corresponding coefficients of friction (rolling and sliding), the force T of the resistance to movement is found: T = fP (as in the case of a sliding friction shutter). When using roller bearings, T can be further reduced. It is in the reduction of T that the advantage of wheel gates lies.

The number of wheels or wheeled carts is assigned four. Wheels (or bogies) are placed on support legs so that they are as equally loaded as possible with hydrostatic pressure. Often they are strengthened in the case of two-transom gates at the ends of the crossbars.

Wheels in relation to a two-wall support column are often located either on the console or in the gap between the walls of the support column (Fig. 21.7). By calculation, you can set the force transmitted to one wheel. Based on this effort, set the radius of the wheel and the width of its rim. The wheel diameter is usually 0.3 ... 1.0 m. The wheels almost always have flanges. Wheeled carts are designed so that there is a hinge between the support post and the corresponding cart, through which the force is transmitted from the gate to two wheels (Fig. 21.8). The width of the grooves in the presence of wheels reaches 3 ... 4 m.

Roller gates (Stoney shields) have support posts resting in grooves on rollers (rollers) connected by a frame (Fig. 21.9).

4. Auxiliary running parts of conventional flat valves. In order to avoid skewing the shutter, shifting it to the side, as well as derailing, auxiliary support parts are arranged: sliding - in the form of various objects, it is considered possible to use a tree. The rubber of the seals must meet certain technical requirements; to protect rubber from abrasion and to reduce friction forces, the sliding surface of rubber is sometimes covered with a metal bar.

The seal is subject to wear, so it should be designed as a replaceable (bolt-on) type. There are two types of seal; 1) seals that come off the surface of the dam when the shutter moves (Fig. 21.10, a); 2) seals during the movement of the valve, sliding on the surface of the dam (for example, side seals of a flat valve).

5. Sliding seals are of two types: sliding along the line AB seals (Fig. 21.10.6); seals sliding across the line AB (Fig. 21.10, c). The design of a cross-sliding seal is the most difficult task, since in this case the friction forces are directed across the seal line AB, and they can turn and break the seals. However, in the case of conventional, flat valves, we often encounter only seals that come off (bottom) and longitudinal sliding (side) and longitudinal sliding; in fig. 21.13 and 21.14 - possible design of these seals. Pairing the bottom to the seals with the side requires a special design development that ensures the tightness of the shutter in this place.

So, in concrete bypassing the embedded parts, to which the seal adjoins, a filtration flow occurs (see Fig. 21.11), and concrete leaching can occur in the area of ​​the embedded part (in the presence of large piezometric slopes and concrete of unsatisfactory quality). At point a (see Fig. 21.11), the hydropathic pressure corresponds to the depth of the water in the upstream; this pressure is zero (in the absence of water in the downstream). Filtration of water along the gap ab will determine the counterpressure W acting on the seal from below the valve and expressed by the triangular diagram abc. The force of lowering (landing) the shutter must overcome, in particular, the force W.

6. Mass of a conventional flat metal shutter. The mass of the shutter in question (its moving part) can be approximately determined by the empirical formula of A. R. Berezinsky

7. Efforts of lifting and lowering a conventional flat valve. It is necessary to distinguish between raising and lowering the shutter: a) in still water (with leveled pools) and b) in flowing water.

When raising and lowering the shutter in flowing water, there are: a) the lifting force of the shutter Sf; b) shutter lowering (landing) force S. When determining the shutter lifting force Sf, in addition to the weight of the shutter G in the air, it is necessary to take into account: the resistance force T to movement due to friction in the supporting parts; Tuple friction force in seals; vertical water pressure Go on the valve from above (if any); suction Rvac (acting from below on the shutter), due to the vacuum formed under the bottom seal.

8. More information about conventional flat metal valves. These valves can be installed on the crest of a spillway dam of any transverse shape; at the same time, they require the construction of a horizontal platform of small width on the crest of the dam (Fig. 21.15). In some cases, such gates can be suspended and matched to the dam with a bottom seal (Fig. 21.15) of cross-slip. Conventional flat gates do not require widening of the dam crest. The flat valve can be easily taken out of the grooves and delivered by a crane to the valve storage for repair in fairly convenient conditions. In the case of tight deadlines, the installation of flat gates can be carried out on the shore and, already assembled, lowered into the grooves.

9. Disadvantages of conventional flat gates: 1) they allow ice to be discharged into the downstream only when the hole is fully opened, which is associated with unnecessary losses of upstream water; 2) in the presence of ice in the upper pool, it is necessary to open the hole to (0.15 ... 0.25) N, and then abruptly switch to full opening. Such operating conditions make the downstream devices more expensive; 3) under harsh conditions winter climate the operation of flat valves is somewhat difficult; 4) the lifting force Sf in the case of a flat gate is large, and therefore the cost of lifting mechanisms is high; 5) bulls in the presence of flat gates are obtained high (see § 18.1); sometimes service bridges are also made heavier. Some of the disadvantages of the conventional flat valve listed above can be mitigated by providing a special type of flat valve.