JP2012031645A - Sedimentation prevention structure for dam or the like - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structure capable of preventing sedimentation from occurring using natural energy by a simple structure.SOLUTION: The structure comprises training dikes 2 located upstream of a dam body 1 provided with a gate 3. The two training dikes 2 are constructed parallel to a current of discharged water with one of ends abutted on an upstream side of the dam body 1. Crown heights of the training dikes 2 are adjusted so as to be lower than a reservoir level 5 but higher than a flood level.

Description

  The present invention relates to a sediment prevention structure such as a dam or a weir.

In dams and dams provided in the direction crossing the river, sedimentation occurs upstream.
Sedimentation is mainly caused by the movement of gravel during floods.
If such sedimentation progresses, it will cause reduction of water storage capacity, riverbank erosion and flooding due to local riverbed rise.
For example, it has now been pointed out that at Taifu Dam (Tenryu River), sedimentation has progressed due to a large amount of sediment flowing out from the upstream Koshibu River, which caused flood damage due to heavy rain in the rainy season front in 1966 (Sanroku flood damage). It has been made.
In recent years, torrential rain accompanying global warming has resulted in localized and centralized rainfall and an extreme increase in rainfall. However, such changes in climate change have caused an increase in sediment discharge during floods. ing.
Especially in flood control dams and multipurpose dams, sedimentation is directly linked to a decline in flood control functions.
In this way, there is no doubt that harmful effects associated with sedimentation can occur if left unattended, and considering the fact that dams are cited as a cause of recent serious beach erosion, measures without delay Is required.
However, until now it has been difficult to prevent the occurrence of sedimentation, so a method for removing the sand that has accumulated has been adopted.
Such a method requires energy such as excavation.
However, in recent years, due to the trend of reducing the amount of CO2 generated, there is a demand for a method for preventing sedimentation by using natural force without using energy.

JP-A-8-134877.

  In the conventional sediment prevention facilities as described in the cited document 1, there is an uneconomic problem that a complicated device is attached to the dam bank.

  In order to solve the above problems, the sediment prevention structure such as a dam according to the present invention is constituted by a dike provided upstream of a dike having a gate, and one end of this dike is Consists of two dikes in contact with the upstream side of the body, parallel to the direction of flow during drainage, and the height of the top of this dike is set lower than the reservoir surface and higher than the water level during floods It is characterized by that.

Since the sediment prevention structure such as a dam of the present invention is as described above, the following effects can be obtained.
<1> Since it is a sediment prevention structure that uses the flow of nature, it does not require special energy and is an efficient structure that is in line with the recent trend of reducing CO2 generation.
<2> Since natural energy is used, it is possible to continue preventing sedimentation over a long period of time.
<3> It is a construction to the extent that a steel sheet pile is placed, and since it is not necessary to install a special device, it can be constructed economically.

The side view of the Example of the sediment prevention structure, such as a dam of this invention. The perspective view of the Example of the sediment prevention structure. The top view of a sediment prevention structure. Explanatory drawing of the sedimentation condition in case the structure of this invention is not installed.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

<1> Status of sedimentation.
First, in order to understand the present invention, the state of sedimentation when the structure of the present invention is not adopted will be described.
At the time of flooding, the gravel is pushed by a large amount of water and moves from upstream to downstream.
When the movement of the gravel reaches the levee body 1 that crosses the flow, the movement is stopped by being guided by a countercurrent bounced back to the structure of the dam body 1 as shown in FIG.
It is considered that a large amount of sediment is generated due to sedimentation of gravel at the portion where movement has stopped.

<2> Diversion dike.
From the above analysis, the gravel sedimentation should not occur unless a countercurrent is generated in the flow of gravel extruded downstream.
Therefore, the structure of the present invention is constituted by the diversion bank 2.
That is, the diversion bank 2 is provided on the upstream side of the bank body 1 including the gate 3.
This diversion bank 2 can be constituted by, for example, a steel sheet pile driven into the ground of the dam bottom 4.
Alternatively, the concrete panels can be constructed in parallel.

<3> Installation location of the diversion dike.
One end of the dike 2 is disposed in contact with the upstream side of the bank 1.
Then, the two dikes 2 are set up in a state of being opposed to each other in parallel with the flow direction when draining the water of the dam from the gate 3.
Then, a water channel can be formed between the two walls.
The two wall-shaped diversion dikes 2 are in contact with the dike body 1 on both sides of the gate 3.
Therefore, the water flow at the time of flood flowing between the two dikes 2 reaches the gate 3 without reducing the tractive force.

<4> Height of the dike.
However, the height of the top of the dike 2 is set lower than the water storage surface 5 and higher than the water level 6 during flooding.
Since it is set higher than the water storage surface 5, the intake of the water storage is not hindered in normal times.

<5> Functions during floods.
During a flood, a rapid stream involving gravel from the upstream approaches the dam body 1.
When the gravel flow approaches the levee body 1, it is guided by the diversion ridge 2 standing on both sides parallel to the flow and moves along the dam bottom 4.
For this reason, the sweeping force that pushes the gravel hardly decreases, reaches the gate 3 directly, and discharges the gravel together with running water to the downstream side.

<6> Water intake.
As shown in FIG. 3, a part of the diversion bank 2 is opened, and this opening can be used as the water inlet 7.
The intake port 7 is opened as one end of the water tunnel 8, and the water intake tunnel 8 forms a flow downstream through the natural mountain.

1: Dam body 2: Diversion dike 3: Gate 4: Dam bottom 5: Water storage surface 6: Water level during flood

Claims (1)

Constructed by a diversion bank provided on the upstream side of a bank body with a gate,
One end of this dike is in contact with the upstream side of the dike and is composed of two dike parallel to the direction of the flow during drainage.
The height of the top of this dike is set lower than the water storage surface and higher than the water surface during floods.
Sediment prevention structures such as dams.

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