JP2008050770A - Deposit evacuation system of dam - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a deposit evacuation system of a dam capable of eliminating environmental pollution caused by the land transportation of soil and making the temporarily-stored soil sufficiently flow to the downstream side, enabling the extended length of a tunnel to be shortened more than before, and having high sand evacuation efficiency. <P>SOLUTION: This deposit evacuation system 10 comprises an evacuation tunnel 11, a submerged breakwater 12, a shaft 13, a stockyard 14, and a deposit force-feed device 30 for charging deposit into the shaft 13. In a normal time when a flood does not occur, the deposit 21 at the bottom of a dam water storage pond 20 is dredged up, temporarily stored in a stockyard 14, charged into a discharge tunnel 11 through the shaft 13, and discharged to the downstream side of the dam water storage pond 20. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a system for discharging sediment accumulated in a reservoir of a dam.

  Sediment and muddy water flow into the reservoir of the dam from the upstream, and deposits such as mud and sediment accumulate on the bottom of the water. The reservoir of a dam is designed after calculating the volume of such sediments in advance. However, due to factors such as unexpected changes in the natural environment, sediments with a volume exceeding expectations may accumulate. is there. The effects of such sediments are generally pointed out such as a decrease in reservoir capacity, an increase in the upstream riverbed, a decrease in the downstream riverbed, a receding coastline, and an impact on the biological environment.

In recent years, it has been required to take measures against sediment problems in dam reservoirs from the viewpoint of comprehensive sediment management of sediment transport systems, and appropriate sediments such as discharging sediments blocked by dams downstream. There have been proposed methods and apparatuses that attempt to restore the continuity through management.
In other words, it is necessary to regularly supply sand to the river downstream of the dam in order to preserve the river bed and coastline downstream of the dam, improve the habitat of fish, and so on. ing. Dams are generally located in mountainous areas, and transportation costs increase when transporting sediments to urban areas and harbors. Therefore, a downstream sediment reduction method has been proposed for discharge during floods with high river turbidity.
In this method, first, the bottom of the reservoir is excavated and dredged, the sediment is transported to the downstream of the dam, temporarily placed, and discharged into the river in the event of a flood. Test construction is in progress. Second, there is a branch weir upstream of the dam reservoir, which is discharged through a bypass tunnel during floods, and is implemented at Asahi and Miwa dams. Third, there is a method of discharging downstream from the bank gate, which is implemented at Unazuki Dam and Deirahira Dam.

However, in the first method, the land transport capacity tends to be insufficient on narrow roads in mountainous areas, and there is an adverse effect on the environment due to land transport, and there are few places to temporarily place earth and sand downstream of the dam. There are many problems, such as not completely flowing.
In the second method, there is a problem that the bypass tunnel becomes long. For example, when the bypass of the reservoir of the Sakuma Dam is completely bypassed, the length of the tunnel extends to about 20 km. Moreover, since the amount of earth and sand discharged is smaller than the amount of water used, the sand discharge efficiency is poor, and it is necessary to treat the coarse particles of the branch weir by land transport after flooding.
In the third method, there is a problem that the construction cost for forming the discharge port in the levee body is high and it is difficult to discharge the coarse particles.
Moreover, as a common problem from the first method to the third method, the sediment already deposited in the reservoir is difficult to treat, and it is impossible to collect the sediment from the reservoir during a flood.

In addition, the sand removal method which provides a bypass tunnel is described in Patent Document 1, and those which provide sand discharge equipment on a bank body are described in Patent Document 2 and Patent Document 3. The inventions described in these patent documents also do not sufficiently solve the above-described problems.
JP 2001-73349 A Japanese Patent Laid-Open No. 11-93147 JP 2005-226301 A

  In view of the current situation as described above, the object of the present invention is that there is no environmental pollution associated with land transportation of earth and sand, the temporarily placed earth and sand can be sufficiently flowed downstream, and the tunnel extension distance is shorter than the conventional one. It is possible to provide a sediment discharge system for a dam with good sand discharge efficiency.

  In the present invention, in order to flow the sediment of the dam reservoir to the downstream with the water, it communicates from the mouth provided near the bottom of the dam reservoir to the outlet downstream of the dam, and a discharge tunnel provided with a gate that can be opened and closed in the middle, From the bottom of the dam reservoir, a submerged dike provided at the bottom of the dam reservoir to guide the sediment along with the water to the mouth of the discharge tunnel, a vertical shaft formed from the dam shore so as to communicate with the discharge tunnel, and from the bottom of the reservoir In order to temporarily store the dredged sediment, the deposit storage facility provided on the shore where the shaft is located, and means for pumping the deposit of the deposit storage site into the shaft are provided. A dam sediment discharge system is provided.

  Here, the means for pumping the sediment in the sediment storage area and feeding it into the shaft is to supply the accumulation tank for storing the sediment in the sediment storage area and the water in the dam reservoir at a relatively high pressure to the vicinity of the accumulation tank. A high-pressure water supply pipe, a high-pressure water supply from the high-pressure water supply pipe, connected to a suction pipe extending from the accumulation tank, and provided with an air introduction hole, and water and air ejected from the ejector And a discharge pipe that allows the mixture of deposits to pass through to the shaft.

In the present invention, the sediment is poured from the bottom of the reservoir during normal times and temporarily placed in the deposit storage area. In this deposit storage area, it is possible to sort by the particle size of the deposit. In addition, at the time of flooding, by opening the gate of the discharge tunnel, sediment containing clay, silt and earth and sand is led to the pier by a submerged dike and flows into the discharge tunnel. At this time, if the sediment temporarily stored in the sediment storage site, especially the sediment mainly composed of sand required for sediment reduction downstream, is put into the shaft, the sediment will join the mud flowing through the discharge tunnel. Both floods can flow downstream.
Therefore, in the system of the present invention, it is possible to proceed the work of putting earth and sand into the discharge tunnel with relatively high safety and reliability without being influenced by the weather such as rainfall.
In addition, the system of the present invention not only has a shaft, but also has means for pumping deposits into the shaft, so that a relatively large amount of earth and sand is introduced into the discharge tunnel in a short time. As a result, the amount of discharged sediment can be increased compared to the amount of water discharged from the reservoir, and the sand discharge efficiency can be significantly improved over the conventional system.
Furthermore, since the system of the present invention is provided with the shed at an arbitrary point in the middle of the reservoir rather than at the uppermost stream of the reservoir, the discharge tunnel can be made shorter than that of the conventional sand removal system. became.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings, but the present invention is not limited thereto.

  As shown in the plan view of FIG. 1 and the cross-sectional view of FIG. 2, the dam deposit discharge system 10 of the present invention includes a discharge tunnel 11, a submerged dam 12, a shaft 13, a stock yard 14, and a deposit. Is provided as a main component with a sediment pumping device 30 for injecting the shaft into the shaft 13, and the sediment 21 at the bottom of the dam reservoir 20 is dredged during normal times, that is, other than during a flood. 21 is temporarily placed in the stock yard 14, and the deposit 21 can be thrown into the discharge tunnel 11 through the shaft 13 during a flood and discharged downstream of the dam reservoir 20.

Here, the discharge tunnel 11 is used to allow the sediment 21 of the dam reservoir 20 to pass downstream along with water during a flood. The discharge tunnel 11 communicates from a pier 11a provided near the bottom of the dam reservoir to a spout 11b downstream of the dam. is doing. The outlet 11a of the discharge tunnel 11 is provided at a position where the flood flow from the upstream can be easily introduced at an arbitrary point in the middle of the dam reservoir 20, and the outlet 11b downstream of the dam is from the drainage tunnel downstream from the dam body. It will be installed at a location where the outflowing flood can easily join the downstream river. The discharge tunnel 11 is provided with a gate 11 c that can be opened and closed upstream of the connection portion with the shaft 13.
The construction method of the discharge tunnel 11 is not particularly limited, but a work space is secured by constructing a temporary cut-off (not shown) in the vicinity of the planned mouth opening, and from the outlet side toward the work space. It is possible to excavate natural ground and form a tunnel.

  The submerged dam 12 is used to dam the sediment 21 containing clay, silt, and earth and sand that has flowed into the dam reservoir 20 from the upstream before reaching the dam body 22 and to guide to the pier 11 a of the discharge tunnel 11. The submerged dike 12 is provided between the left and right grounds 23a and 23b so that the submerged dike 12 is not perpendicular to the dam axis and is angled toward the pier 11a of the discharge tunnel 11. In addition, the submerged dike 12 is arranged at an arbitrary position in the middle of the dam reservoir 20 so that the flood flow can be easily guided to the pier 11a in consideration of the shape of the reservoir 20 and the flow of the flood flow.

The stock yard 14 is a place for temporarily placing the sediment 21 dredged from the bottom of the reservoir 20, from which the sediment 21 is sent out to the shaft 13. Therefore, it is preferable to provide the stock yard 14 at a position very close to the reservoir 20 and as close as possible to the shaft 13 on either one of the left and right banks. In the stock yard 14, it is possible to provide a device (not shown) for sorting earth and sand mainly composed of sand from other components, or sorting deposits by particle size. Sediment mainly composed of sand required for sediment reduction downstream can be efficiently supplied downstream of the dam. In addition to the device for sorting the deposit 21, it is preferable to provide a device for moving the deposit such as the bulldozer 16 in the stock yard 14. It is thrown.
Further, as an additional facility that can be brought close to the stock yard 14, for example, there is a gantry 18 for docking a dredging device such as a carriage 17 and unloading deposits from the carriage 17. If an unloading machine such as a crane 19 is installed on the gantry 18, the deposit can be unloaded from the trolley 17 and unloaded to the stock yard 14 as it is.

  The shaft 13 is formed substantially vertically from the dam shore so as to communicate with the middle of the discharge tunnel 11 from the pier 11a to the discharge port 11b, and the deposit 21 temporarily placed in the stock yard 14 is discharged from the tunnel. 11 is a passage for dropping to 11. The ground opening of the shaft 13 is not particularly limited, but it is desirable to arrange it close to the stock yard 14. Although the construction method of the shaft 13 is not particularly limited, the shaft 13 is constructed if excavation is performed substantially vertically upward by a reaming machine or the like (not shown) at a predetermined position of the discharge tunnel 11. It is possible.

  The sediment pumping device 30 is a means for pumping the sediment 21 temporarily placed in the stock yard 14 and putting it in the shaft 13. The sediment loading hopper 31, the high-pressure water supply pipe 32, the ejector 33, The discharge pipe 34 is provided as a main configuration.

  Here, each configuration of the deposit pumping apparatus 30 will be described in more detail. The earth and sand injection hopper 31 moves the deposit 21 temporarily placed in the stock yard 14 by using a bulldozer or the like, and temporarily inserts it. It is for housing and is provided in the stock yard 14 or adjacent to the stock yard 14. An ejector 33 is connected to the lower end of the earth and sand charging hopper 31 through a pipe 35.

  The high-pressure water supply pipe 32 is a pipe extending from the dam reservoir to the vicinity of the stockyard, and an engine pump 32a is provided in the middle of the dam reservoir or in the dam reservoir. The engine pump is for supplying water from the dam reservoir to the vicinity of the stockyard at high pressure.

The ejector 33 is a device that has been conventionally used as a compressor or a vacuum pump. The ejector 33 is a vacuum pump that uses high-pressure jet water as a drive source and does not have a mechanical drive unit. The principle of the ejector 33 is to eject high-pressure water from a nozzle. The other fluid (here, earth and sand) is sucked and pumped by the kinetic energy. That is, as shown in FIG. 5, the nozzle 33b is provided at the upstream end of the main body portion 33a, the air introduction hole 33c and the suction pipe 33d are provided slightly downstream from the nozzle 33b, and the interior of the main body portion 33a is provided with an interior. The pipe 33e is fixed, and the discharge pipe 34 is connected to the downstream end 33f. The nozzle 33 b is a nozzle that ejects the high-pressure water sent through the high-pressure water supply pipe 32. The air introduction hole 33c is automatically controlled to introduce an optimum amount of air, which is effective for suppressing cavitation. A pipe 35 extending from the vicinity of the lower end of the earth and sand charging hopper 31 is connected to the suction pipe 33d, and the suction energy generated by the ejection of high-pressure water is transmitted to the earth and sand, thereby sucking the earth and sand to the main body 33a of the ejector 33. The inner pipe 33e is effective as a measure against the wear of the pipe body of the main body 33a because of its easy replacement.
In the main body portion 33 a of the ejector 33, earth and sand, air, and water are mixed, and this mixture is further pumped to the shaft 13 through the discharge pipe 34 and introduced from the ground opening of the shaft 13.

Next, the operation method and operation of the deposit discharge system 10 of the present invention will be described.
In the system of the present invention, the sediment 21 is dredged from the bottom of the dam reservoir 20 in a normal state and temporarily placed in the stock yard 14. It is possible to sort out sediment mainly composed of sand required for sediment reduction downstream from the deposit 21, and this sediment is placed in a section near the shaft 13 in the stock yard 14 or in the sediment input hopper 31. Place it in a nearby compartment.
On the other hand, at the time of water discharge, the gate 11c of the discharge tunnel 11 is opened, and water is poured into the discharge tunnel 11 from the well 11a together with deposits including clay, silt, and earth and sand, and at the same time, the deposit pumping device 30 is operated.
That is, the earth and sand temporarily placed in the stock yard 14 is moved by the bulldozer 16 or the like and is put into the earth and sand charging hopper 31. At this time, high-pressure water is ejected from the high-pressure water supply pipe 32 to the main body 33a of the ejector 33, and air is introduced from the air introduction holes 33c. Sediment is sucked from the charging hopper 31. The sucked earth and sand are mixed with water and air in the main body 33 a, sent out from the discharge pipe 34, and put into the shaft 13. Since the sediment is highly fluidized by being mixed with water and air at a high pressure by the ejector 33, it can be pumped even at a considerably high concentration, and a relatively large amount of sediment can be thrown into the shaft 13 in a short time. This makes it possible to increase the amount of discharged sediment compared to the amount of water discharged from the dam reservoir 20, and to significantly improve the sand discharge efficiency as compared with the conventional system.
When the earth and sand are thrown into the shaft 13, they join the flood flowing through the discharge tunnel 11, and are discharged from the outlet 11b downstream of the dam.

It is a top view of the sediment discharge system of the dam concerning this invention. It is sectional drawing of the deposit discharge system of the dam concerning this invention. FIG. 2 is a partially enlarged plan view of FIG. 1. FIG. 3 is a partially enlarged cross-sectional view of FIG. 2. It is a side view of the ejector used for this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Dam sediment discharge system 11 Discharge tunnel 11a Anchor 11b Discharge 11c Gate 12 Submerged dike 13 Shaft 14 Stockyard (sediment storage)
20 Dam Reservoir 21 Sediment 30 Sediment Pumping Device (Means for Pumping Sediment and Putting it in a Vertical Shaft)
31 Sediment input hopper (accumulation tank)
32 High-pressure water supply pipe 33 Ejector 33b Nozzle 33c Air introduction hole 33d Suction pipe 33e Interior pipe 34 Discharge pipe

Claims (2)

  In order to allow the sediment in the dam reservoir to flow downstream along with the water, there is a discharge tunnel with a gate that can be opened and closed in the middle of the dam reservoir. A submerged embankment at the bottom of the dam reservoir to guide sediment along with the water to the estuary, a vertical shaft formed almost vertically from the dam shore to communicate with the discharge tunnel, and a sediment dredged from the bottom of the reservoir In order to temporarily place an object, there is provided a deposit yard provided on the shore where the shaft is located, and means for pumping the deposit of the deposit yard and feeding it into the shaft, Waste discharge system.   The means for introducing the sediment into the shaft is a collection tank for storing the deposit in the sediment storage site, a high-pressure water supply pipe for supplying water in the dam reservoir to the vicinity of the accumulation tank at a relatively high pressure, and the high-pressure water supply A suction pipe extending from the accumulation tank, connected to a suction pipe connected to the collection tank and having an air introduction hole, and a mixture of water, air and the deposits ejected from the ejector, The dam sediment discharge system according to claim 1, further comprising a discharge pipe that leads to the shaft.

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