JP7382596B2 - dam spillway system - Google Patents

Description

TECHNICAL FIELD The present invention relates to a spillway device for a dam. Note that "flood" is not a flood in the narrow sense, but refers to a large amount of water flowing into a dam lake, and a "spillway" refers to a facility that discharges a large amount of water from a dam lake downstream. .

When a large amount of water flows into a dam lake, conventional dams open the top gate installed at the top of the dam body to prevent the water level from rising.
However, in recent years, due to changes in the global environment, heavy rains that occur once every several hundred years have begun to occur. In the case of such heavy rain, it is assumed that the water discharging capacity from the top gate is insufficient, and various countermeasures have been proposed (see, for example, Patent Document 1 (FIGS. 1 and 2)).

Patent Document 1 will be explained based on FIG. 10.
FIG. 10A is a sectional view of a main part of a conventional dam, in which a main gate 101 is provided at the top of an embankment body 100. By opening the main gate 101, the water level of the dam lake 103 can be lowered. The height dimension of the spout is A.
According to the technique disclosed in Patent Document 1, the top of the embankment body 100 is cut down to an excavation line 104 shown by an imaginary line.

FIG. 10(b) is a diagram illustrating a conventional dam spillway device, and the height of the spout is B, which is larger than A. Then, a sub-gate 105 is added to the embankment body 100 along the excavation line 104. By opening the main gate 101 and the sub-gate 105, a larger amount of water 106 can now be spouted than in FIG. 10(a).

However, upon study by the present inventors, it was found that the technique of Patent Document 1 has the following problems.
The water 106 shown in FIG. 10(b) is a natural overflow. The flow velocity V1 obtained by natural overflow is 1 to 5 m/s.

However, in order to cope with the heavy rain that occurs once every several hundred years, the flow velocity must be 10 m/s or more.
That is, the spillway device disclosed in Patent Document 1 has insufficient water discharging ability.

Therefore, a dam spillway device with a sufficiently large water discharge capacity is required.

Japanese Patent Application Publication No. 2003-253657

An object of the present invention is to provide a spillway device for a dam that has a sufficiently large water discharge capacity.

The invention according to claim 1 is a spillway device for a dam that is attached to a dam and includes a crown gate at the top of an embankment body, and discharges water that cannot be discharged by the crown gate,
A siphon pipe insertion part provided in the embankment body at a lateral position of the top gate, a siphon pipe inserted into the siphon pipe insertion part, a gate attached to the siphon pipe, and a control for opening and closing the gate. It consists of
The siphon pipe has an inverted U-shaped intermediate part buried in the siphon pipe insertion part, and extends from one end of the intermediate part and sinks into the surface layer of the dam lake to take in water from the surface layer of the dam lake. It consists of a water intake part, and a water discharge part extending from the other end of the intermediate part along the downstream side of the embankment body and discharging water,
The gate is provided at the outlet of the water spouting part,
Equipped with a water level gauge to measure the water level of the dam lake,
The control unit closes the gate when the water of the dam lake flows through the siphon pipe in a free overflow state based on the water level information of the water level gauge, and closes the gate when the water discharge part is full or almost full. The present invention is characterized in that the gate is opened to form a siphon flow with a large water discharging capacity, thereby obtaining an undisturbed siphon flow.

The invention according to claim 2 is a spillway device for a dam that is attached to a dam and includes a crown gate at the top of an embankment body, and discharges water that cannot be discharged by the crown gate,
A siphon pipe insertion part provided in the embankment body at a lateral position of the top gate, a siphon pipe inserted into the siphon pipe insertion part, a gate attached to the siphon pipe, and a control for opening and closing the gate. It consists of
The siphon pipe has an inverted U-shaped intermediate part buried in the siphon pipe insertion part, and extends from one end of the intermediate part and sinks into the surface layer of the dam lake to take in water from the surface layer of the dam lake. It consists of a water intake part, and a water discharge part extending from the other end of the intermediate part along the downstream side of the embankment body and discharging water,
The water spouting portion is bent so that the siphon flow from the siphon pipe collides with the natural overflow from the adjacent top gate, and the outlet of the water spouting portion is directed toward the center in the width direction of the embankment body. Ori,
The gate is provided at the outlet of the water spouting part,
The control unit closes the gate when the water of the dam lake flows through the siphon pipe in a free overflow state, and opens the gate when the water discharge part becomes full or almost full to form a siphon flow. It is characterized by

In the invention according to claim 1, in addition to the top gate, a siphon pipe is provided on the embankment body. If the flow is a siphon flow, a flow velocity of 10 m/s or more can be obtained.
By adding up the water discharged by the crown gate (natural overflow) and the water discharged by the siphon pipe (siphon flow), a sufficiently large water discharge capacity can be obtained.
Therefore, the present invention provides a dam spillway device having a sufficiently large water discharge capacity.

Further, in the invention according to claim 1, a gate is attached to the siphon pipe, and by controlling the opening degree of the gate by the control section, it is possible to control the amount of water discharged from the dam.

In the invention according to claim 2, the water spouting portion is bent such that the outlet of the water spouting portion is directed toward the center in the width direction of the embankment body. Opening the top gate allows natural overflow. Since the water discharge part is bent, the water discharged from the siphon pipe collides with the natural overflow, resulting in a synergistic effect in which the outflow energy is attenuated and the natural overflow is also attenuated.

It is a front view of the dam seen from the downstream side. 2 is a sectional view taken along line 2-2 in FIG. 1. FIG. It is an operational diagram of the top gate. 2 is a sectional view taken along line 4-4 in FIG. 1. FIG. It is a diagram explaining the action of a siphon pipe, (a) is a natural overflow, (b) is a closed gate, and (c) is a diagram explaining a siphon flow. It is a figure explaining the effect|action of the curved water discharge part. It is a figure explaining the example of a change of a siphon tube insertion part. It is a figure explaining the further modification example of a siphon tube insertion part. It is a figure explaining the further effect|action of a gate. (a) is a sectional view of a main part of a conventional dam, and (b) is a diagram illustrating a spillway device of a conventional dam.

Embodiments of the present invention will be described below based on the accompanying drawings. Note that the drawings should be viewed in the direction of the symbols.

As shown in FIG. 1, the dam 10 includes a plurality of (three in this example) top gates 13 on the top 12 of the embankment body 11, and a spillway device 20 (hereinafter abbreviated as spillway device 20) of the dam. ) is equipped with two units. The top gate 13 is also called a crest gate.

The main element of the spillway device 20 is a siphon pipe 21, and this siphon pipe 21 is inserted into a siphon pipe insertion part 14 provided in the embankment body 11 at a position lateral to the top gate 13.
In this embodiment, the siphon tube insertion portion 14 is an opening 14A provided in the top portion 12 of the embankment body 11.

The opening size of the opening 14A is desirably set to be the same as or larger than the opening size of the top gate 13, but this does not preclude setting it smaller.
Since the opening dimensions are different, "the lateral position of the top gate 13" includes "the substantially lateral position of the top gate 13". That is, the top gate 13 and the opening 14A (siphon tube insertion part 14) need only be lined up left and right, and there is no problem in having a difference in height.

As shown in FIG. 2, the top gate 13 is closed and the water level 16 of the dam lake 15 is at the top 12 of the embankment body 11. If the water level 16 rises any further, the top gate 13 will be opened. Note that the top gate 13 is not limited to a slide gate, but may be a radial gate, and any type or format may be used.

As shown in FIG. 3, water in the dam lake 15 overflows over the top 12. That is, a natural overflow 17 is obtained.

With natural overflow 17, the downward velocity at top 12 is approximately zero. Because potential energy is converted to velocity energy, the flow velocity increases as you go down. Since the natural overflow 17 is a continuous flow, the thickness W of the natural overflow 17 becomes smaller toward the bottom. The flow velocity V1 of the natural overflow 17 is about 1 to 5 m/s.

As shown in FIG. 4, the spillway device 20 includes a siphon pipe 21 inserted into the siphon pipe insertion portion 14, a gate 30 provided at the outlet of the siphon pipe 21, and a control unit 40 that controls opening and closing of the gate 30. It consists of. In addition, a water level gauge 41 for measuring the water level of the dam lake is lowered from the crown bridge 18, and water level information measured by the water level gauge 41 is sent to the control unit 40.

The siphon pipe 21 includes an intermediate part 22 that has an inverted U shape and is buried in the siphon pipe insertion part 14, and a water intake part that extends from one end of the intermediate part 22 and is submerged in the dam lake 15 to take in water from the dam lake 15. 23, and a water spouting portion 24 extending from the other end of the intermediate portion 22 along the downstream side surface 11a of the embankment body 11 and spouting water.

The gate 30 is preferably a tension type radial gate in which the valve body 32 is located downstream of the rotation support shaft 31. As shown in FIG. 1, side plates 33, 33 extend from the rotation support shafts 31, 31, and a valve body 32 is spanned over the tips of these side plates 33, 33. The valve body 32 is driven by a hydraulic cylinder 34 and rotated around the rotation support shaft 31 . The hydraulic cylinder 34 is preferably a hydraulic cylinder or a hydraulic cylinder.
Note that the gate 30 is not limited to a radial gate, but may be a slide gate, and any type or format may be used.

When water pressure is applied to the valve body 32, a tensile force is applied to the side plates 33, 33. Explain the benefits of tensile force.
If a steel plate is subjected to a compressive force rather than a tensile force, it is likely to buckle. When subjected to compressive forces, the steel plate should be made thicker to withstand buckling. The side plate 33 becomes heavy.
On the other hand, when receiving a tensile force, there is no need to increase the thickness, and the weight of the side plate 33 can be reduced.

The operation of the spillway device 20 described above will be explained based on FIG. 5.
In FIG. 5(a), the water level 16 of the dam lake 15 is somewhat above the top 12. The control unit (FIG. 4, reference numeral 40) opens the gate 30 based on the water level information from the water level gauge 41. Then, a natural overflow 17 is formed within the siphon pipe 21.

Due to heavy rain, water level 16 will rise further. When the water level 16 approaches the highest position 25 of the siphon pipe 21, the gate 30 is closed. During the process of closing the gate 30, natural overflow 17 accumulates in the siphon pipe 21. This amount of accumulated water increases over time, and the siphon pipe 21 approaches its full capacity.

Then, as shown in FIG. 5(b), the water spouting section 24 becomes full or almost full. "Almost full of water" refers to a state in which air 26 remains in the intermediate portion 22 that has an inverted U shape. When the siphon tube 21 is substantially filled with water, the control unit (FIG. 4, reference numeral 40) opens the gate 30.
Then, the water accumulated in the siphon pipe 21 flows. This flow is expected to cause some (or all) of the air 26 to be exhausted.

Then, as shown in FIG. 5(c), a siphon flow 27 is formed in the siphon pipe 21. The siphon flow 27 has an in-pipe flow velocity V2 of 10 m/s or more.
As described above, the spillway device 20 with sufficiently large water discharging capacity is provided.

Due to the large amount of water discharged, the water level 16 of the dam lake 15 is lowered. When the water level 16 falls below the inlet of the water intake section 23, air flows in and the siphon flow 27 collapses. Next, when the water level 16 rises, it becomes as shown in FIG. 5(a).

Next, the function of the curved water spouting section 24 will be explained based on FIG. 6.
As shown in FIG. 6(a), the siphon tube 21 may have a straight shape. However, a siphon flow 27 is formed approximately parallel to the natural overflow 17 from the top gate 13. Since the siphon flow 27 has a flow velocity V2 of 10 m/s or more, the velocity energy is much larger than that of the natural overflow 17, and a hole 43 is formed at the falling point after a certain period of time.

As shown in FIG. 6(b), when the water discharge part 24 of the siphon pipe 21 is bent toward the center in the width direction of the embankment body 11, the siphon flow 27 collides with the adjacent natural overflow flow 17 and may coalesce. Be expected. This reduces the momentum of the siphon flow 27 and makes it difficult to form a hole at the falling point, which is preferable.
Furthermore, since the water spouting portion 24 is bent, a synergistic effect is obtained in that the water spouted from the siphon pipe 21 collides with the natural overflow 17, and the outflow energy is attenuated and the natural overflow 17 is also attenuated.

In FIGS. 1 and 4, the siphon tube insertion portion 14 is the opening 14A, but the siphon tube insertion portion 14 is not limited to the opening 14A. A specific example thereof will be explained based on FIGS. 7 and 8.
As shown in FIG. 7A, the siphon tube insertion portion 14 may be a levee crest recess 14B cut in the levee body 11.
As shown in FIG. 7(b), the siphon pipe 21 is attached (dropped) into the levee crest recess 14B, and the surplus portion of the levee crest recess 14B is filled with concrete 44.

In addition, the embankment crest recess 14B may be made shallow and the concrete 44 may be omitted as shown in FIG. 7(c).

As shown in FIG. 8(a), the embankment body 11 is provided with a top gate 13 called a crest gate.
Using this top gate 13, a siphon pipe 21 may be attached to the top gate 13, as shown in FIG. 8(b).

As explained above, the siphon tube insertion portion 14 of the present invention may be any of the opening 14A (FIG. 1), the crest recess 14B (FIG. 7), the top gate 13 (FIG. 8), or Any similar item is fine.
That is, the siphon tube insertion section 14 of the present invention only needs to be able to insert the siphon tube 21, and its form is not limited to the embodiment.

Next, further operation of the gate 30 will be explained based on FIG. 9.
As shown in FIG. 9A, when the gate 30 is fully opened, the internal pressure of the siphon pipe 21 may drop depending on the conditions, and air 26 may enter from the outlet. When air 26 enters, the siphon flow 27 is disturbed and the flow velocity is reduced.

In that case, as shown in FIG. 9(b), the gate 30 is slightly closed by the control section (FIG. 4, reference numeral 40). Then, the internal pressure of the siphon pipe 21 increases, and air 26 can be prevented from entering. As a result, an undisturbed siphon flow 27 is obtained, and a decrease in flow velocity can be avoided.

It should be noted that the present invention can be applied not only to newly constructed dams but also to existing dams. That is, the siphon pipe insertion part 14 may be opened in the embankment of an existing dam, and the siphon pipe 21 may be attached to this siphon pipe insertion part 14. This makes it possible to increase the discharge capacity of existing dams.

The present invention is suitable for dams that require flood countermeasures and increased discharge capacity.

10... Dam, 11... Embankment body , 12... Top, 13... Top gate, 14... Siphon pipe insertion part, 15... Dam lake, 16... Water level of dam lake, 17... Natural overflow, 20... Dam spillway Device, 21... Siphon pipe, 22... Intermediate section, 23... Water intake section, 24... Water discharge section, 27... Siphon flow, 30... Gate, 40... Control section, V1... Flow velocity in natural overflow, V2... In siphon flow flow rate.

Claims (2)

A spillway device for a dam that is attached to a dam and includes a crown gate at the top of an embankment body, and discharges water that cannot be discharged by the crown gate,
A siphon pipe insertion part provided in the embankment body at a lateral position of the top gate, a siphon pipe inserted into the siphon pipe insertion part, a gate attached to the siphon pipe, and a control for opening and closing the gate. It consists of
The siphon pipe has an inverted U-shaped intermediate part buried in the siphon pipe insertion part, and extends from one end of the intermediate part and sinks into the surface layer of the dam lake to take in water from the surface layer of the dam lake. It consists of a water intake part, and a water discharge part extending from the other end of the intermediate part along the downstream side of the embankment body and discharging water,
The gate is provided at the outlet of the water spouting part,
Equipped with a water level gauge to measure the water level of the dam lake,
The control unit closes the gate when the water of the dam lake flows through the siphon pipe in a free overflow state based on the water level information of the water level gauge, and closes the gate when the water discharge part is full or almost full. A spillway device for a dam, characterized in that the gate is opened to form a siphon flow with a large discharge capacity, thereby obtaining an undisturbed siphon flow. A spillway device for a dam that is attached to a dam and includes a crown gate at the top of an embankment body, and discharges water that cannot be discharged by the crown gate,
A siphon pipe insertion part provided in the embankment body at a lateral position of the top gate, a siphon pipe inserted into the siphon pipe insertion part, a gate attached to the siphon pipe, and a control for opening and closing the gate. It consists of
The siphon pipe has an inverted U-shaped intermediate part buried in the siphon pipe insertion part, and extends from one end of the intermediate part and sinks into the surface layer of the dam lake to take in water from the surface layer of the dam lake. It consists of a water intake part, and a water discharge part extending from the other end of the intermediate part along the downstream side of the embankment body and discharging water,
The water spouting portion is bent so that the siphon flow from the siphon pipe collides with the natural overflow from the adjacent top gate, and the outlet of the water spouting portion is directed toward the center in the width direction of the embankment body. Ori,
The gate is provided at the outlet of the water spouting part,
The control unit closes the gate when the water of the dam lake flows through the siphon pipe in a free overflow state, and opens the gate when the water discharge part becomes full or almost full to form a siphon flow. A dam spillway device characterized by:

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