JPS6248007B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fish belly type overturning gate with excellent sand removal performance.

[Conventional technology]

Overturning gates installed at water intake points of rivers, etc. are always upright to allow water to overflow, keeping the water level on the upstream side constant, and when the water rises, they completely fall down on the downstream side and open fully, allowing water to flow out immediately. It has a distribution function. Sediment carried from upstream by overflow water is always deposited on the riverbed downstream of the tipping gate, and even if the tipping gate is attempted to be lowered downstream when the water rises, there is a risk that the gate will not be able to be fully opened due to the sediment.

As a solution to this problem, as disclosed in Japanese Patent Application Laid-open No. 48-42554, a chute (flow path) leading from the top of the gate body to the bottom of the gate body is provided inside the door body of the overturning gate, and the exit of the chute is connected to the gate body. By opening toward the downstream at the lower end of the gate body when the gate is erected, overflow water from the gate normally flows down exclusively through the chute, and is deposited downstream of the overturning gate by the water flow jetting downstream from the outlet. It is proposed to exclude sediment.

[Problem that the invention seeks to solve]

The above-mentioned conventional overturning gate equipped with a chute can remove sediment from the riverbed near the lower end of the downstream side of the overturning gate by the water flow ejected from the chute outlet, but the sediment moves slightly downstream and accumulates.
Since this position corresponds to the tipping position of the top of the door body, there is a risk that the door body may not be able to completely fall down when the water rises.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an overturning gate that can completely remove earth and sand from the river bed downstream of the overturning gate by flowing water so that the gate body can be completely collapsed when the water rises.

Still another object of the present invention is to provide an overturning gate which has a cavity inside the chute and which is free from the possibility of vibration or cavitation of the gate body.

[Means for solving the problem] In a tipping gate equipped with a chute, most of the overflow water from the tipping gate is normally discharged through the chute, but as the water level on the upstream side gradually rises, the water overflowing from the chute The water overflows directly from the top of the door body to the downstream side. When the water level on the upstream side reaches a certain predetermined water level when the water rises, it is necessary to completely collapse the gate and release water. Until the water level rises to the desired water level, the overflow water from the top of the gate is discharged as forcefully and for as long as possible to completely eliminate the sediment on the riverbed where the gate collapses. can do. Furthermore, in the above-mentioned tipping gate equipped with a conventional chute, when water directly overflows the top of the gate body, the overflow water collides with the upper end of the inner wall on the downstream side of the chute, causing a jump in the water vein, which disrupts the flow of the overflow water. As a result, the flow velocity of overflow water over the gate body is weakened, and since the upper end of the outer wall on the downstream side of the gate body has an angular shape, the energy loss of the water flow due to this part cannot be ignored. By improving the shapes of the upper end of the inner wall on the downstream side of the chute and the upper end of the outer wall on the downstream side of the door body, overflow water can be discharged and fallen with force without loss of kinetic energy of overflow water. As a result of intensive research, the present inventors discovered the above and completed the present invention.

That is, the present invention provides a fish-belly type overturning gate that rotates around the lower end of the door body, is supported so as to be able to rise and fall, and has a chute that penetrates the door body vertically. It opens upward at the top of the door body, and when the door body is erected at the maximum normal standing angle, the straight line connecting the upper edge of the upstream side and the upper edge of the downstream side of the entrance section is tilted downstream at a small inclination angle from the horizontal. The outlet part of the chute is opened toward the downstream side near the lower end of the door body, and the inlet part is covered with a filter screen, and the downstream inner wall surface of the chute and the downstream outside of the door body are covered with a filter screen. The wall surface has a curved surface curved toward the upstream side near the upper end thereof, and one end of a spoiler communicating with the atmosphere is inserted into the upstream corner of the lower side of the filter screen in the chute. The gist is the overturning gate.

Next, the content of the present invention will be explained in detail with reference to embodiments of the drawings. FIG. 1 is a sectional view of the overturning gate of the present invention. Reference numeral 1 denotes a door body of a fish belly type overturning gate, which is rotatably supported via a shaft 2. An inlet portion 5 of a chute 4 opens upward at the top 3 of the door body 1, and the inlet portion is formed by a straight line connecting the upper edge on the upstream side and the upper edge on the downstream side when the door body is erected to the normal maximum upright angle. When facing the downstream side 7, it forms an inclination angle θ (approximately 5 degrees) downward from the horizontal. Further, the downstream wall surface 8 near the inlet portion 5 of the chute forms a curved surface curved in the upstream direction with a radius of curvature R, and the chute inlet portion 5 is covered with a filter net 6. Shoot 4
passes through the inside of the chute 4 along the back plate 11 of the door body 1, and extends toward the downstream side at the bottom of the door body at the outlet portion 1.
Open 2. Normally, tipping gates are used in two rotational positions: when standing up, they stand at a certain designed standing angle in order to maintain the upstream water level at a set constant water level, and when falling down, they are completely laid down.
It is never used by stopping at an intermediate rotational position. Therefore, in the present invention, the term "commonly used maximum standing angle" means a fixed standing angle set in the above-mentioned design. The door body of the overturning gate of the present invention is configured to be rotatable between a fixed upright angle set in the design, that is, the normal maximum upright angle and the fully collapsed position. It may be possible to rotate beyond the above set upright angle.

A spoiler 10 is made of a tube or a plate having a V-shaped or U-shaped cross section, one end of which is inserted into the upstream corner 9 under the filter screen in the chute, and the other end is open to the atmosphere. 15 is a watertight part.

[Effect]

In the above-mentioned overturning gate, when the flow rate is always small, all the water that overflows the gate passes through the filter screen 6 and flows into the inlet section 5.
The liquid flows into the chute 4 from above and is ejected downstream from the chute outlet 12 at the lower end of the overturning gate.
Due to the jet flow, the sediment that is about to accumulate near the downstream river bed 13 adjacent to the overturning gate is swept downstream, and some of it is deposited slightly downstream.

When the water rises a little and all the water overflowing the gate cannot flow into the chute, some of it overflows from the top of the overturning gate and is divided into inflow water Q1 and overflow water Q2 into the chute. At this time, the entrance part 5 of the chute
Slightly lower the height of the upper end of the downstream side than the upper end of the upstream side,
Since the downstream wall surface 8 is curved toward the upstream side, the water flowing into the chute flows along the curved wall surface 8 toward the upstream side, and the flow direction can be smoothly bent, so that it is not like a conventional overturning gate. The water flow will not collide with the downstream wall of the chute and cause water veins to jump up. Since the overflow water Q2 flows smoothly along the outside of the wall surface 8 curved upstream, the water flow is not disturbed, and the overflow water falls forcefully to the downstream side without loss of speed and is deposited there. Accumulated sediment can be removed.

Furthermore, in this state, both the inflow water Q1 and the overflow water Q2 can flow at a high flow rate, so at a constant overflow height h (difference between the height of the upstream water surface and the top of the gate body), the total overflow flow rate ( Inflow water Q1 + overflow water Q2) can be made considerably large. Therefore, when the flow rate from upstream gradually increases from a small flow rate, the time from when the chute inlet overflows starts to overflow until the upstream water level reaches a predetermined water level determined to overturn the overturning gate is extended, During this time, a larger amount of overflow water is allowed to flow down, and the sediment that accumulates on the downstream side when the flow is small can be completely removed.

A filter screen 6 provided at the inlet 5 of the chute separates solids contained in the flowing water, prevents large solids from flowing into the chute and clogging it, and solids separated on the filter screen 6 Since the filter net itself is arranged downward facing the downstream side, the overflow water Q2 washes away into the downstream river and does not stay on the filter net, so that the filter net always has good flowability. kept in condition.

Depending on the upstream water level or the standing state of the gate,
Water that has flowed into the chute may separate from the upstream wall surface of the chute, creating a cavity.In addition to causing cavitation, the cavity narrows the chute, causing the inside of the chute to become narrower. Since the flow of water is obstructed, it is necessary to prevent the formation of cavities as much as possible. In order to prevent the formation of cavities, it is preferable that the upstream inner surface of the chute inlet section be a wall surface curved toward the upstream side. Furthermore, the generated cavity floats to the bottom upstream corner of the filter screen 6 at the inlet and stays there, so if the tip of the spoiler 10 is inserted into this part and communicated with the atmosphere, the cavity can be corrected. In the case of pressure, the air in the cavity is exhausted by the spoiler and the cavity disappears.

If the slope θ of the line connecting the upper end of the upstream side and the upper end of the downstream side of the chute inlet section 5 is increased, for example, if it is sloped downward at 30 degrees toward the downstream side, the chute will be The flow rate of overflow water flowing along the steeply sloped filter net 6 at the inlet increases,
Therefore, the velocity head of the overflow water increases, and the static water head decreases by that amount. As a result, the hydrostatic head within the chute is reduced accordingly, and the cavity within the chute is likely to become under negative pressure, making it easy for the door body to vibrate and cavitate. When a spoiler is inserted into this cavity, atmospheric air is sucked in by negative pressure, and the cavity actually expands and the inflow water Q1 decreases significantly, so it is not preferable to increase the inclination θ of the inlet 5.

In the present invention, instead of the spoiler 10,
The tip is opened at the upstream corner 9 of the upper end of the chute,
It is also possible to provide a suction pipe 14 whose base end opens to the outlet section 12 at the lower part of the chute to forcibly exhaust the air in the cavity to eliminate the cavity.

〔Effect of the invention〕

According to the overturning gate of the present invention, it is possible to completely remove accumulated sediment from the river bed downstream of the overturning gate over a wide area. When the flow is small, the jet from the chute removes sand from the area adjacent to the overturning gate, and when the water rises before a flood, overflow water completely removes sand from the downstream side, allowing the overturning gate to always be lowered without any problems. .

The shape of the chute entrance and the spoiler prevent the formation of a cavity inside the chute, and prevent vibration and cavitation of the door body.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of the overturning gate of the present invention. 1... Door body, 2... Shaft, 3... Top, 4... Chute, 5... Inlet, 6... Filter net, 7... Downstream side, 8... Wall surface, 9... Corner, 10... Spoiler, 11... Back plate, 12... Outlet section, 13... Riverbed, 14... Suction pipe, 15... Watertight section.

Claims (1)

[Claims] 1. In a fishbelly type overturning gate which has a chute that rotates around the lower end of the door body, is supported so as to be able to rise and fall, and penetrates the door body vertically, the inlet of the chute is It opens upward at the top, and is formed so that when the door body is erected at the normal maximum upright angle, a straight line connecting the upstream upper end edge and the downstream upper end edge of the entrance section is inclined downstream at a small inclination angle from the horizontal; The outlet part of the chute is opened toward the downstream side near the lower end of the door body, and the inlet part is covered with a filter net, and the downstream inner wall surface of the chute and the downstream outer wall surface of the door body are each covered with a filter net. An overturning gate characterized by having a curved surface curved toward the upstream side near the upper end, and having one end of a spoiler communicating with the atmosphere inserted into the upstream corner below the filter screen in the chute. .