Water level linked type overflow height automatic adjustment gate

Abstract

To provide a water level-linked automatic overflow height adjusting gate capable of letting a large amount of river water flow into a floodplain after overflow has started, while suppressing the frequency of river water overflowing into the floodplain. [Solution] At the bottom 13b of an overflow levee 13 formed one level lower than the levee 11, there is a horizontal rotation axis 2 installed with its axial direction facing horizontally along the flow of the river 100, a gate body 3 installed so as to be able to swing freely within a range from an initial position tilted at a predetermined angle to a tipping position where it is tipping towards the floodplain, and a weight 4 which determines the weight balance of the gate body 3 around the horizontal rotation axis 2, the weight of which is adjusted so that when no water pressure is applied to the gate body 3 from the river side, it keeps the gate body 3 upright in its initial position, and when the river water level rises and exceeds the tipping start water level set at a position higher than the horizontal rotation axis 2, it is able to tip the gate body 3 under water pressure from the river side.

Description

[Technical Field]

[0001] The present invention relates to a water-level-linked automatic overflow height adjusting gate that is installed on an overflow levee to allow swollen river water to overflow into a floodplain before it overflows the levee. [Background technology]

[0002] Flood disasters have been increasing due to abnormal weather in recent years. Until now, the main flood prevention measure has been to build levees on rivers. However, recently, there have been cases where large amounts of rain have fallen locally, such as linear rain bands, and the amount of water rising has exceeded the estimates made when levees were designed, which has led to an increase in flood disasters.

[0003] Therefore, there has been an increase in the construction of flood retarding basins and overflow levees as new flood prevention measures. Flood retarding basins are normally used as farmland, etc., and are facilities that temporarily store water only when the river overflows. The boundary between this flood retarding basin and the river is built with a levee called an overflow levee, which is lower than the surrounding levees, and this allows water to flow into the flood retarding basin before the river water level exceeds the levee, preventing flooding.

[0004] However, if the height of the overflow levee is too low compared to the height of the levee, water will flow into the retarding basin more frequently, hindering its use as farmland, etc. Conversely, if the difference in height between the overflow levee and the levee is small, the amount of water flowing into the retarding basin will be small, and the basin will not be able to keep up with the rising water level of the river, resulting in flooding.

[0005] To address these issues, attempts are being made to use movable gates that can adjust the inflow volume instead of fixed weirs for overflow levees. For example, Non-Patent Document 1 describes an example in which a torque-axis gate structure that can be forcibly collapsed is used. Non-Patent Document 1 argues that movable gates that can be adjusted according to flood level are effective in maximizing the flood control effect of retarding basins.

[0006] Incidentally, there has been a floating-type elevation gate that can be opened and closed automatically. For example, Japanese Patent Application Laid-Open No. 2013-76294 proposes a floating elevation gate facility in which the gate body is installed on the riverbed using a hinge system, and the gate automatically rises and falls due to buoyancy in response to fluctuations in the river water level (Patent Document 1). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-76294 [Non-patent literature]

[0008] [Non-Patent Document 1] Tadashi Suetsugu and Fuga Aizawa, "Considerations on measures to maximize the flood control function of flood retarding basins," Japan Association for Soil and Water Conservation, Water Science No. 367, June 2019, pp. 25-37 Summary of the Invention [Problem to be solved by the invention]

[0009] However, the method of adjusting the inflow rate using a movable gate described in Non-Patent Document 1 has the problem of requiring huge costs for hydraulic equipment to forcibly lower the movable gate. Also, there are inconveniences and safety issues during operation, as an operator must go to the site to operate the gate in the event of a flood.

[0010] Furthermore, the invention described in Patent Document 1 has a gate that automatically rises as the water level of the river rises. When installed on an overflow levee, this can reduce the frequency of inflow into the floodplain, but there is a problem in that when the river overflows, the difference in elevation between the levee and the gate is small, so the amount of inflow into the floodplain is reduced and flooding cannot be prevented.

[0011] The present invention has been made to solve the above problems, and aims to provide a water level-linked automatic overflow height adjustment gate that can reduce the frequency with which river water overflows into the floodplain, while allowing a large amount of river water to flow into the floodplain once overflow has begun. [Means for solving the problem]

[0012] The water level-linked automatic overflow height adjusting gate of the present invention is a water level-linked automatic overflow height adjusting gate that allows water to overflow into a retarding basin adjacent to the levee when the river water level rises above a predetermined height, in order to solve the problem of automatically adjusting the height of the gate that starts overflow from the overflow levee into the retarding basin and the river water level, and is provided with a horizontal rotating shaft that is installed at the bottom of the overflow levee, which is formed one step lower than the levee, with its axial direction facing horizontally along the river flow, and a portion near its lower end supported by the horizontal rotating shaft, The gate has a door body that is installed so that it can swing freely within a range from an initial position inclined at a predetermined angle to a tipping position where it is tipping toward the floodplain, and a weight body that is attached to the lower edge of the gate body and determines the weight balance of the gate body around the horizontal rotation axis.The weight of the weight body is adjusted so that when no water pressure is applied to the gate body from the river side, it keeps the gate body upright in the initial position, and when the river water level rises and exceeds the tipping start water level that is set at a position higher than the horizontal rotation axis, it receives water pressure from the river side and tip over the gate body.

[0013] In addition, as one aspect of the present invention, in order to solve the problem of preventing water stored in a floodplain from flowing back into the river, the weight of the weight body may be adjusted to a weight that returns the door body to its initial position when the water level difference between the floodplain water level and the river water level falls below a predetermined value when the floodplain water level has risen to a height above the horizontal rotation axis. [Effects of the Invention]

[0014] According to the present invention, it is possible to suppress the frequency of river water overflowing into the retarding basin, while allowing a large amount of river water to flow into the retarding basin after overflow has begun. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a bird's-eye view showing an embodiment in which a water-level-linked automatic overflow height adjusting gate according to the present invention is installed on an overflow levee. [Figure 2] FIG. 1 is a side view showing a water level-linked automatic overflow height adjusting gate according to the present embodiment. [Figure 3] FIG. 1 is a front view showing a water level-linked automatic overflow height adjusting gate according to the present embodiment. [Figure 4] FIG. 2 is an assembly diagram showing the door body and the weight body in this embodiment. [Figure 5] FIG. 10 is a bottom view showing the state in which the weight head is attached to the door body in this embodiment. [Figure 6] FIG. 10 is a cross-sectional view showing a state in which a weight is attached to a door body in this embodiment. [Figure 7] This is a side view showing the water level-linked automatic overflow height adjustment gate of this embodiment when the river water level is normal. [Figure 8] This is a side view showing the water level-linked automatic overflow height adjusting gate of this embodiment when the river water level rises and the gate body is subjected to water pressure. [Figure 9] This is a side view showing the water level-linked automatic overflow height adjustment gate of this embodiment when the river water level reaches the overturning start water level. [Figure 10] This is a side view showing the water level-linked automatic overflow height adjustment gate of this embodiment when the door body falls toward the floodplain. [Figure 11] This is a side view showing the water-level-linked automatic overflow height adjusting gate of this embodiment when the river water level drops and the gate body is tilted toward the floodplain. [Figure 12] This is a side view showing the water-level-linked automatic overflow height adjusting gate of this embodiment when the gate body rises and returns to its initial position due to a drop in the river water level. [Figure 13] This is a side view showing the water-level-linked automatic overflow height adjustment gate of this embodiment when the door body is tilted toward the floodplain and the water level difference between the river water level and the floodplain water level reaches a predetermined value. [Figure 14] This is a side view showing the water-level-linked automatic overflow height adjustment gate of this embodiment when the gate body returns to its initial position because the water level difference between the river water level and the floodplain water level has fallen below a predetermined value. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, an embodiment of a water level-linked automatic overflow height adjusting gate according to the present invention will be described with reference to the drawings.

[0017] First, a brief explanation will be given of the floodplain 10. The floodplain 10 is a facility into which water is poured and temporarily stored when the river water level rises to a predetermined height, and as shown in Figure 1, it is composed of a levee 11 and a surrounding levee 12. In addition, an overflow levee 13 and a floodgate 14 are installed on the levee 11 between the floodplain 10 and the river 100.

[0018] The overflow levee 13 is designed to channel water from the river 100 into the retarding basin 10 before it overflows the levee 11 when the river water level rises, and is formed one step lower than the height of the levee 11. As shown in Figures 1 and 3, the overflow levee 13 in this embodiment is formed in a concave shape with left and right side portions 13a and a bottom portion 13b between the side portions 13a.

[0019] 1 and 2, fan-shaped side panels 13c are embedded in both the left and right side portions 13a, and are made to abut against watertight rubber 31 provided on both the left and right edges of the door body 3, which will be described later, to prevent water leakage between the river side and the floodplain side. The cross section of the bottom portion 13b is formed into a substantially trapezoidal shape, and the water level-linked automatic overflow height adjustment gate 1 is installed on this bottom portion 13b.

[0020] The floodgate 14 is used to discharge water temporarily stored in the floodplain 10 into the river 100 after the risk of flooding has passed, and in this embodiment, a slide gate is installed that can be opened and closed by raising and lowering the door. However, the floodgate 14 is not limited to a slide gate.

[0021] The water level-linked automatic overflow height adjustment gate 1 is a gate that is installed on the overflow levee 13 to automatically adjust the height at which water from the river 100 overflows into the floodplain 10, and is installed at the bottom 13b of the overflow levee 13, which is formed one step lower than the levee 11, as shown in Figures 1 to 3.

[0022] As shown in Fig. 2, the water-level-linked automatic overflow height adjusting gate 1 of this embodiment has a horizontal rotation shaft 2 installed at the bottom 13b of the overflow levee 13, a door body 3 journaled on the horizontal rotation shaft 2, and a weight 4 provided at the lower edge 36 of the door body 3. Each component will be described in detail below.

[0023] The horizontal rotation shaft 2 is a rotation shaft for rotatably supporting the gate body 3, and is installed at the bottom 13b of the overflow levee 13 as shown in Figures 2 and 3. The axial direction of the horizontal rotation shaft 2 is oriented horizontally and is installed horizontally along the flow of the river.

[0024] As shown in Fig. 3, each horizontal rotation shaft 2 in this embodiment is a short shaft extending in the left-right direction, and one door body 3 is supported by three horizontal rotation shafts 2. As shown in Fig. 2, each horizontal rotation shaft 2 is installed on the river side of the bottom 13b.

[0025] The number of horizontal rotation shafts 2 supporting one door body 3 is not limited to three, but may be selected appropriately depending on the size and weight of the door body 3, etc.

[0026] The gate body 3 swings on the overflow levee 13 to adjust the height (water level) at which water from the river 100 overflows into the retarding basin 10, holding back the water from the river 100 under normal conditions and allowing it to overflow into the retarding basin 10 when the water level rises and there is a risk of flooding (risk of water overflowing the levee 11). As shown in Figures 2 and 3, the gate body 3 in this embodiment is formed in a substantially rectangular shape with a left-to-right length equal to the left-to-right width of the overflow levee 13. Watertight rubber 31 is attached to both left and right edges of the gate body 3, and this watertight rubber 31 abuts against side panels 13c provided on the side portions 13a of the overflow levee 13 to maintain a watertight state between the river side and the retarding basin side.

[0027] This door body 3 is journaled near its lower end on the horizontal rotation shaft 2. Specifically, as shown in Fig. 2, a bearing portion 32 is formed to protrude toward the retarding basin near the lower end of the door body 3, and the bearing portion 32 is journaled on the horizontal rotation shaft 2. In this embodiment, the door body 3 is supported so that its upper edge portion 33 is at a position lower than the height of the levee 11 in the initial position.

[0028] In addition, an inclined support portion 34 that supports the gate body 3 in the initial position is installed on the sloped surface on the river side of the overflow levee 13, and a tipping support portion 35 that supports the gate body 3 in the tipping position is installed on the bottom 13b of the overflow levee 13.

[0029] As a result, the door body 3 is supported by the inclined support portion 34 and the tipping support portion 35, and can swing freely within a range from an initial position inclined at a predetermined angle toward the floodplain relative to the vertical state to a tipping position in which it is tipping toward the floodplain, making it possible to greatly change the overflow height (the position of the upper edge portion 33 of the door body 3) from the initial position to the tipping position.

[0030] In this embodiment, the gate body 3 is composed of a single piece, but this is not limited to this, and a configuration in which multiple pieces are connected together to block the entire width of the overflow levee 13 may also be adopted.

[0031] The weight body 4 is a weight for determining the weight balance of the door body 3 around the horizontal rotation axis 2, and is attached to the lower edge 36 of the door body 3. As shown in Figures 4 to 6, the weight body 4 in this embodiment is composed of a weight guide 41 extending straight downward from the lower edge 36 of the door body 3, an adjustment weight 42 attached along this weight guide 41, and a fastening member 43 that fixes the adjustment weight 42 to the door body 3.

[0032] The weight guide 41 is a guide member for attaching the adjustment weight 42, and in this embodiment, as shown in Figures 4 and 5, it consists of a channel steel member 411 extending downward from both the left and right ends near the lower end of the door body 3, and four H-shaped steel members 412 arranged at approximately equal intervals between these left and right channel steel members 411, and is configured so that the adjustment weight 42 can be attached between these channel steel members 411 and H-shaped steel members 412.

[0033] The number and spacing of the H-shaped steel members 412 are not particularly limited, and may be selected appropriately depending on the left-right width dimension of the door body 3. Furthermore, the weight guide 41 is not limited to a configuration made up of channel steel members 411 and H-shaped steel members 412, and may be made up of a box-shaped member that can accommodate the adjustment weight 42.

[0034] The adjustment weight 42 is a weight for adjusting the weight of the weight body 4 by being installed on the lower edge 36 of the door body 3, and is made of stainless steel or iron (specific gravity: approximately 7.5 to 7.9), and is formed in a substantially rectangular parallelepiped shape so that it can be attached by sliding along the weight guide 41. As shown in Figures 4 and 5, the adjustment weight 42 in this embodiment is provided with an annular locking portion 421 for locking onto a rope or hook from a crane during installation, and as shown in Figure 6, has a plurality of bolt insertion holes 422 that penetrate vertically.

[0035] In addition, in this embodiment, multiple types of adjustment weights 42 with different weights (sizes) are provided, and the weight of the weight body 4 can be adjusted by appropriately selecting the type and number of adjustment weights 42 to be attached to the weight guide 41.

[0036] The material of the adjustment weight 42 is not limited to stainless steel or iron, but may be selected appropriately from other metallic materials.

[0037] The fastening member 43 is a member for fixing the adjustment weight 42 to the door body 3, and in this embodiment, is composed of a long bolt 431 that is inserted into the bolt insertion hole 422 of the adjustment weight 42, and a nut 432 that is screwed onto this long bolt 431. Specifically, as shown in Fig. 6, the long bolt 431 is inserted into the bolt insertion hole 422 of the adjustment weight 42 and the bolt hole 37 in the lower edge portion 36 of the door body 3, and the nuts 432 are screwed onto both the upper and lower ends to fasten and fix the door body 3 to the door body 3.

[0038] The method of fixing the adjustment weight 42 is not limited to using the fastening member 43, but it may also be fixed to the door body 3 or the weight guide 41 by welding or the like.

[0039] The weight of the weight 3 in this embodiment is adjusted as follows: First, when no water pressure is applied to the gate body 3 from the river side, the gate body 3 stands up in its initial position, and when the river water level rises and exceeds the tipping start water level set at a position higher than the horizontal rotation axis 2, the weight is adjusted so that the gate body 3 is overturned by the water pressure from the river side.

[0040] In other words, the gate body 3 is supported near its lower end. At this time, the part above the horizontal rotation axis 2 is heavy, so if left as is, it will tip over into the floodplain due to its own weight. The weight of the weight body 4 is provided to raise the gate body 3 to its initial position when it is in a tipping state, and a weight body 4 is adopted that ensures that the weight of the lower gate body 3, including the weight body 4, is heavier than the weight of the gate body 3 above the horizontal rotation axis 2.

[0041] Furthermore, when the river water level rises to a position higher than the horizontal rotation axis 2, water pressure is applied to the river side of the gate body 3, creating a force that tends to tip the gate body 3 over, and when this force in the tipping direction exceeds the force in the upright direction, the gate body 3 tips over.

[0042] The weight of the weight body 4 can be adjusted to adjust the water level at which it starts to tip over. In this embodiment, in order to reduce the frequency with which water from the river 100 flows into the floodplain 10, the height corresponding to the upper edge 33 of the door body 3 in its initial position is adjusted as the water level at which it starts to tip over.

[0043] In addition, in this embodiment, the weight of the weight body 4 is adjusted to allow the door body 3 to return to its initial position when the water level difference H between the floodplain water level and the river water level falls below a predetermined value, in order to prevent the water stored in the floodplain 10 from flowing back into the river 100.

[0044] In other words, as the amount of overflowing water increases, the water level in the retarding basin 10 rises. When the water level in the retarding basin 10 rises above the horizontal rotation axis 2, forces such as buoyancy and water pressure from the retarding basin side act on the gate body 3. The water pressure from the water on the retarding basin side acts as a force in the direction of raising the gate body 3 and returning it to its initial position. At this time, the smaller the water level difference H between the river water level and the retarding basin water level, the smaller the force tending to overturn the gate body 3, and when the force causing it to rise due to the weight of the weight 4 exceeds this force, the gate body 3 returns to its initial position.

[0045] Therefore, the weight of the weight 4 is adjusted to return it to its initial position when the water level difference H between the river water level and the floodplain water level becomes equal to or less than a predetermined value (river water level - floodplain water level ≦ predetermined value).

[0046] The weight 4 is not limited to a configuration in which it extends straight downward from the lower edge 36 of the door body 3, but may extend in a curved state toward the river side, etc. The tipping start water level is not limited to the height corresponding to the upper edge 33 of the door body 3 in the initial position, but may be set at a position higher or lower than the upper edge 33 as long as it can reduce the frequency with which water from the river 100 flows into the retarding basin 10.

[0047] Next, the operation of each component of the water level-linked automatic overflow height adjusting gate 1 of this embodiment will be described.

[0048] When the river water level is normal, no water pressure is applied to the gate body 3 from the river side, as shown in Figure 7. The weight of the gate body 3 below the horizontal rotation axis 2 is greater than the weight above it due to the weight of the weight 4, so the gate body 3 stands upright in its initial position.

[0049] As shown in Figure 8, when the river water level rises and exceeds the horizontal rotation axis 2, the water pressure from the river side acts in a direction that causes the gate body 3 to tip over toward the retarding basin. However, when the river water level is below the tipping start water level, the weight of the weight 4 exerts a stronger force in the direction that causes the gate body 3 to stand up, so the gate body 3 can maintain its initial position. Therefore, even if the river water level rises above the height of the bottom 13b of the overflow levee 13, the water of the river 100 does not overflow, thereby reducing the frequency of overflow.

[0050] On the other hand, as shown in Figure 9, when the river water level exceeds the tipping start water level (in this embodiment, the upper edge 33 of the gate body 3), the force of water pressure in the direction of tipping the gate body 3 exceeds the force of the weight 4 in the direction of standing the gate body 3. As a result, the gate body 3 rotates around the horizontal rotation axis 2 and tips over towards the retarding basin. In this embodiment, the tipping start water level is set lower than the levee 11, so the gate body 3 tips over before the water in the river 100 overflows the levee 11.

[0051] As shown in Figure 10, when the gate body 3 is overturned, the position of the upper edge 33 of the gate body 3 becomes lower than the river water level, and the water of the river 100 flows over the overturned gate body 3 into the floodplain 10. The floodplain 10 can prevent overflow (flooding) from the levee 11 by storing the flowing water. After that, the gate body 3 is subjected to water pressure according to the water depth, and as long as this force exceeds the force that raises the gate body 3, the gate body 3 will remain in the overturned state even if the river water level falls below the overturning start water level.

[0052] As the river water level continues to drop, the water depth decreases and the force of the flowing water weakens, as shown in Figure 11. Then, when the force due to water pressure corresponding to the water depth above the gate body 3 falls below the force exerted by the weight 4 or the like in the direction of raising the gate body 3, the gate body 3 automatically rises, as shown in Figure 12. The gate body 3 then holds back the water in the river 100 until the river water level again exceeds the overturning water level. This makes it possible to minimize the inflow of water from the river 100 into the retarding basin 10.

[0053] When water from the river 100 flows into the retarding basin 10, the retarding basin water level rises and the difference in water level H between the basin water level and the river water level gradually decreases, as shown in Fig. 13. As this difference in water level H decreases, the force of the flowing water weakens, and when the difference in water level H eventually falls below a predetermined value, the force in the direction to raise the gate body 3 exceeds the force in the direction to overturn the gate body 3, and the gate body 3 automatically rises and returns to its initial position, as shown in Fig. 14.

[0054] After the gate body 3 returns to its initial position, if the river water level rises, for example, and the water level difference H between the river water level and the floodplain water level exceeds a predetermined value, the gate body will tip over again, allowing water to flow into the floodplain 10.

[0055] In this way, the gate body 3 repeatedly falls over and returns to its original position, gradually causing the water level in the floodplain 10 to rise, but in either case the gate body 3 automatically returns to its initial position before the floodplain water level becomes higher than the river water level, thereby reliably preventing the water accumulated in the floodplain 10 from flowing back into the river 100.

[0056] Finally, when the river water level drops to normal, the floodgates 14 are opened and the water stored in the floodplain 10 is discharged into the river 100. Once the water has been discharged, the floodplain 10 can be used again as farmland or the like.

[0057] According to the present embodiment as described above, the following advantageous effects can be achieved. 1. The gate body 3 does not tip over until the river water level exceeds the tipping start water level, so the frequency with which water from the river 100 flows into the floodplain 10 decreases, making it easier to use the floodplain 10 as farmland, etc. 2. When the river water level exceeds the tipping start water level, the gate body 3 automatically tips over and the height of the upper edge 33 of the gate body 3 drops significantly, allowing a large amount of water from the river 100 to flow into the floodplain 10 and preventing flooding that would cause the water in the river 100 to overflow the levee 11. 3. When the river water level drops to a certain level, the gate body 3 automatically rises and blocks the water until it exceeds the water level at which the river begins to tip over. This minimizes the inflow of water into the floodplain 10, reduces the impact on the floodplain 10, and makes it easier to return the basin to agricultural land, etc. 4. The gate body 3 automatically rises when the water level difference H between the floodplain water level and the river water level falls below a predetermined value, thereby reliably preventing water accumulated in the floodplain 10 from flowing back into the river 100.

[0058] The water level-linked automatic overflow height adjusting gate according to the present invention is not limited to the above-described embodiment and can be modified as appropriate. For example, a watertight member may be provided between the lower edge 36 of the gate body 3 and the overflow dam 13 to prevent water leakage from the vicinity of the horizontal rotation axis 2. [Explanation of symbols]

[0059] 1 Water level-linked overflow height automatic adjustment gate 2 horizontal rotation axis 3 Door body 4 Pyramid 10 Floodplain 11 Embankment 12 Surrounding embankment 13 Overflow levee 13a Side 13b bottom 13c Side Panel 14 Floodgate 31 Watertight rubber 32 Bearing section 33 Upper edge 34 Inclined support part 35 Fall support 36 Lower edge 37 bolt holes 41 Weight Guide 42 Adjustment weight 43 Fastening members 411 Channel steel 412H steel material 421 Locking part 422 Bolt insertion hole 431 Long Bolt 432 Nut 100 Rivers

Claims

1. A water level-linked automatic overflow height adjustment gate that allows water to overflow into a retarding basin adjacent to the levee when the river water level rises above a predetermined height, a horizontal rotation shaft installed at the bottom of an overflow levee formed one step lower than the levee, the axial direction of which is oriented horizontally along the flow of the river; a door body whose lower end is supported by the horizontal rotation shaft and which is installed so as to be able to swing freely within a range from an initial position inclined at a predetermined angle to a tilted position tilted toward the retarding basin; a weight provided at the lower edge of the door body to determine the weight balance of the door body around the horizontal rotation axis; It has The weight of the weight body is adjusted to a weight that allows the gate body to stand in its initial position when no water pressure is applied to the gate body from the river side, and to allow the gate body to tip over under water pressure from the river side when the river water level rises and exceeds the tipping start water level set at a position higher than the horizontal rotation axis, in this water level-linked overflow height automatic adjustment gate.

2. A water-level-linked automatic overflow height adjusting gate as described in claim 1, wherein the weight of the weight body is adjusted to a weight that returns the door body to its initial position when the water level difference between the floodplain water level and the river water level becomes less than a predetermined value when the floodplain water level has risen to a height above the horizontal rotation axis.

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