JPH0435562B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for filtering soil particles contained in river water. The invention also relates to a method of filtering running water to separate soil particles and the like.

[Conventional technology]

In order to remove soil particles floating in flowing water of a river, a method has been used since ancient times to install a settling pond on the upstream side and separate the particles in advance. In the settling basin, large and heavy sand and soil particles are settled and removed, but fine and light soil particles, e.g.
Silt and clay with a diameter of 100 μm or less tend to be difficult to settle. Silt and other debris that is not removed will muddy the water and flow down the river. on the other hand,
During flood seasons when rainfall is abnormally high, sand and other soil particles that have settled in settling basins often become suspended in the flowing water and flow away due to the turbulent flow of water.

[Problem to be solved by the invention]

If murky water from rivers flows directly into the sea, the water at tourist spots and beaches will be contaminated, hindering the ability to attract tourists, and causing economic damage to local residents. In addition, as silt floating in the ocean gradually settles, it can clog the gravel layer on the ocean floor. This causes the seaweed to wither and, by extension, abalone and other underwater creatures to die, causing so-called rockfish blight. Of course, if coral reefs exist, their habitat will deteriorate, leading to the destruction of nature.

On the other hand, erosion control dams are a conventional method of filtering soil particles contained in river water. Sabo dams are generally referred to as sediment control dams, but if the soil particles are small or the amount of soil mixed in is large, a filter effect cannot be obtained, so they are usually used in conjunction with a settling basin. However, there is a problem in that most of the silt and clay, which are the main components of turbidity in running water, cannot be removed even if they pass through a settling basin because most of them take a very long time to settle.

The present invention was made in view of the above-mentioned problems, and its purpose is to remove silt, clay, etc. from river water that follows the river and flow into the sea, and to make it possible to settle it. To provide a filter method that can prevent natural destruction such as pollution of beaches and seawater and drying up of rocky shores.

Incidentally, the present invention is based on the traditional purification technology of filling a container with gravel or sand and purifying the turbid water poured in from above, so that it can be applied to flowing water in rivers. It was developed into Thereby, it is possible to filter running water mixed with a large amount of earth and sand, and also remove the turbid components, thereby suppressing the re-flow of the turbid components even during a flood.

[Means to solve the problem]

The features of the method of filtering soil particles contained in river water according to the present invention are as shown in Fig. 1.
A gravel layer 3 higher than the normal water level h is constructed in the river 1, a weir is formed with a permeable wall 5 to stabilize the shape of the gravel layer 3, and this is installed on the downstream side 3b of the gravel layer 3, and the flowing water 2 While flowing through the gravel layer 3, the soil particles in the flowing water 2 are separated, and when the gravel layer 3 becomes clogged, the gravel 4 and the trapped soil particles 18 are removed.
This was done by replacing it with new gravel 4.

As shown in FIG. 2, the permeable wall 5A may also be provided on the upstream side 3a of the gravel layer 3.

As shown in FIGS. 3 and 4, a settling pond 11 with a wider river width is provided on the upstream side 3a of the gravel layer 3,
The flowing water 2 from which the coarse soil particles 18a have been removed in the sand settling basin 11 may be allowed to flow into the gravel layer 3.

As shown in FIG.
It is also possible to bury a pipe body 12 covered with a water-permeable material 13 to prevent gravel 4 from entering.

In addition, as shown in Fig. 6, water 2 flows into the gravel layer 3.
The water conduit 14 or groove that guides the upstream side 3a
The flowing water 2 may be actively guided into the gravel layer 3 by a passage provided through the permeable wall 5A located in the flow direction.

As shown in FIG. 7, the gravel 4 can be packaged to facilitate replacement of the gravel 4.

In any of the above methods, instead of the gravel 4 (see Figure 1), as shown in Figure 8, a water-permeable material 1 is used.
5 can also be adopted.

〔Effect of the invention〕

According to the present invention, a gravel layer constructed in a river is maintained in a stable cross-sectional shape by a weir formed of a permeable wall. Even if the flowing water is turbid, the soil particles contained in the flowing water are captured by the gravel layer while it flows through the gravel layer, so that a large amount of flowing water can be efficiently purified and allowed to flow down. When river water is purified, when it flows into the ocean, beaches and seawater are cleaner, and pollutants and soil particles are prevented from settling on the ocean floor.
Therefore, drying up of the seashore and destruction of nature will be prevented, and the natural environment will be preserved.

On the other hand, when the gravel layer becomes clogged due to trapped soil particles, the gravel and trapped soil particles can be removed and replaced with new gravel, regenerating the purification function of the gravel layer and creating a permanent purification effect. maintained.

If a permeable wall is provided on the upstream side of the gravel layer, the gravel layer will maintain a more stable shape and posture, and its purification effect will be improved.

If a settling basin with a wider river width is installed upstream of the gravel layer, coarse soil particles contained in the flowing water will settle in the settling basin and be removed in advance, mainly only fine particles such as silt and clay will be removed. It can be separated by a gravel layer. In that case, since those fine particles are efficiently removed, the water flowing out from the gravel layer becomes a clear stream that is even more purified.

By burying a tube whose end face is capped with a water-permeable material to prevent gravel from entering into the gravel layer, the gaps formed between the gravels will be increased and the trapping function of the gravel layer will be enhanced. . The trapping effect of the gravel layer is also increased when a water conduit or groove is provided that penetrates the permeable wall on the upstream side and is arranged in the flow direction so as to actively guide the flowing water into the gravel layer.

If the gravel is packaged, it has the advantage of being extremely easy to replace after the amount of trapped gravel increases.

If a permeable material is used instead of the gravel described above, it is possible to exhibit the effect of removing soil particles, etc., as in the case of using a gravel layer.

〔Example〕

Hereinafter, the method of filtering soil particles contained in river water according to the present invention will be explained in detail with reference to the drawings including the filter structure.

As shown in FIG. 1, a gravel layer 3 higher than the normal water level h of the flowing water 2 is built on the riverbed 1a of the river 1. This gravel layer 3 is made up of a plurality of gravels 4 which are filter materials. By the way, gravel 4 is made by crushing collected stones by mechanical processing, for example, with a particle size of 20 cm.
degree or smaller than that. A permeable wall 5 such as a concrete wall or a frame dam is formed on the downstream side 3b of the gravel layer 3, thereby forming a weir so as to stabilize the shape of the cross section of the gravel layer 3. In this example, the transparent wall is a frame dam described below.

As shown in FIG. 9, the frame dam is composed of a horizontal member 6a, a vertical member 6b, and an anteroposterior connecting member 6c made of, for example, section steel.After these are partially assembled in advance at a factory or the like, Delivered to the site. Then, these iron materials 6 are sequentially assembled into a framework 7 by bolting, welding (not shown), or the like. On the other hand, inexpensive filling soil 8 is prepared by mixing soil cement in an amount of 5 to 10% with the currently excavated sand collected from the riverbed 1a or river bank. A water-permeable bag 9 is filled with packed earth and sand 8 and cured, and the earth and sand bag 10 whose inside is solidified is put into the framework body 7. The frame dam 5 formed in this manner has water permeability that allows the flowing water 2 to flow through. In other words, it is normally a weir with the same function as a permeable frame dam in which crushed stone is placed inside the framework body 7, and the weir 5 and the gravel layer 3 form the filter structure shown in FIG. 16 is formed. In addition,
The weir may be a concrete wall (not shown), with a portion of the wall having water permeability.

Flowing water 2 on the upstream side of the river 1 shown in Fig. 1 is turbid, and floating soil particles (silt) flow through the gravel layer 3 formed by piling up gravel 4 with gaps. ), etc., are settled and separated, and the flowing water 2 that has passed through the gap is purified. When the inside of the gravel layer 3 becomes clogged after nearly a year, the gravel 4 and the trapped soil particles 18 are removed and replaced with new gravel 4 each time. Therefore, the purification function of the filter structure 16 is maintained, and environmental destruction of the coast and seashore into which river water flows is prevented.

By the way, we collected running water before and after the gravel layer,
The results of the field demonstration tests analyzed using the Coulter counter method are shown in Figures 10 to 12. As can be seen from these data, more than 70% of the soil particles contained in the turbid water, with a particle size of 1 μm to 20 μm, are filtered. When this filter structure 16 is used, the re-outflow of soil particles 18 that have separated and accumulated in the gaps between the gravel layers during floods is suppressed, according to a study by Mr. Nagaoka and Ogaki. This can be fully inferred from the biological self-cleaning effect of the structured river bed. In other words, the report states that the velocity of seepage flow in a gravel layer approaches zero near the third layer from the surface, regardless of the size of the gravel diameter. The validity of this is confirmed. Therefore, even if a gravel layer is made of gravel with a diameter of about 20 cm, it is necessary to ensure that the settling time is sufficient to filter out small soil particles with a particle size of 1 μm. Even if the water rises, the accumulated soil particles will not flow out again.

In the example of FIG. 2, in addition to the permeable wall 5 provided on the downstream side 3b of the gravel layer 3, the upstream side 3b of the gravel layer 3
A permeable weir 5A is also installed in a, and the filter structure 16 is formed by the two permeable walls 5, 5A and the gravel layer 3.
is formed. In this example, the gravel layer 3 is made a little taller, and the two transparent walls 5 and 5A make the gravel layer 3
shape is maintained, soil particles 18, etc. are efficiently removed, and purification of the turbid stream is promoted.

In the examples shown in FIGS. 3 and 4, a settling pond 11 is formed on the upstream side 3a of the gravel layer 3, that is, upstream of the permeable wall 5A, which is wider than the river 1 and has a deeper river bed 11a. has been done. The turbid flow flowing into the settling basin 11 from the upstream is the wide settling basin 1.
1, the flow rate is extremely weakened, large soil particles 18a, for example, those larger than 100 μm are removed, and the gravel layer 3 is effectively purified. That is, the permeable wall 5 installed on the upstream side 3a of the gravel layer 3
The turbid stream that entered the gravel layer 3 from A separates silt and clay with small particle sizes, e.g., 100 μm or less, while flowing through the gravel layer 3, becoming a clear stream and flowing into the downstream side 3.
It flows out from the permeable wall 5 of b. Since large-sized soil particles 18a and the like are separated in advance in the settling basin 11,
This has the advantage that clogging in the gravel layer 3 is alleviated and the gravel layer 3 can last longer.

By the way, it is said that the gap between gravels is limited to about 40% of the total area of the gravel layer. Therefore, as shown in FIG. 5, in order to widen the gap in the gravel layer 3, a corrosion-resistant material such as
It is preferable to use a plurality of vinyl chloride pipes (four shown) each having a length of about 50 cm, and bury the pipe body 12 therein. The end surface 12a of the tube body 12 is covered with a water-permeable material 13, which is a water-permeable mat, to prevent gravel 4 from entering the tube body 12.
In this way, the filter structure 16 in which the pipe body 12 is buried has a wide gap for retaining the soil particles 18, etc., and as a result, the capacity for capturing soil particles per unit volume of the gravel layer 3 is increased, and the filter structure Layer 16
Purification function is enhanced.

The example shown in FIG. 6 has a plurality of water pipes 14 (one shown) penetrating the permeable wall 5A located on the upstream side 3a of the gravel layer 3, installed in the river bed 1a, and running along the flow direction. It is. In this case, the running water 2 flowing from upstream is actively guided into the gravel layer 3. As a result, almost all of the flowing water 2 is quickly purified within the gravel layer 3 that constitutes the filter structure 16.
Note that instead of the water conduit 14, a channel may be formed by excavating a groove [not shown] in the riverbed 1a that penetrates the permeable wall 5A on the upstream side 3a and extends from the permeable wall 5A to the gravel layer 3. good.

FIG. 7 shows an example in which a group of gravels 4 constituting the gravel layer 3 are restrained by a cage body 17 made of rust-free steel wire, etc., and the gravels 4 are put into a package. When the clogging in the gravel layer 3 that occurs with the passage of time progresses, a group of gravel 4 that is packaged
This has the advantage that it is easy to lift up and lower down using a crane vehicle or the like, and that a group of gravel 4 can be quickly replaced. Note that, without using the cage 17, a group of gravels 4 may be packed into a bag (not shown) to form a package. It is also possible to use a bag filled with sand as a sandbag, but in that case, place large-sized gravel near the surface, or
Water-permeable pine may be interposed to prevent water from being washed away during floods.

The above is an example in which gravel 4 (see Fig. 1) is used, but as shown in Fig. 8, a water-permeable material such as water-permeable pine, which has gaps (not shown) to accommodate soil particles and has water permeability, can be used instead. The same effect can be achieved even if the materials 15 are assembled and placed on the river bed 1a. In addition, water-permeable pine is
For example, it may be made of a fibrous material that is compacted to allow water to pass through, but any material that allows fine particles to be trapped in the gaps may be used.

Incidentally, weirs 5 and 5A are provided on the upstream side 3a and downstream side 3b of the gravel layer 3, a settling basin 11 is formed upstream of the gravel layer 3, a pipe body 12 is buried in the gravel layer 3, and If a water pipe 14 or the like is formed, the purification effect will be further improved.

As can be seen from the above explanation, if the gravel layer built in a river is stably held by a permeable wall, floating soil particles will be removed from the gravel layer while flowing water flows through the gravel layer even if the water is turbid. It is possible to efficiently purify large amounts of running water. When rivers are purified, there is less pollution when they flow into the ocean, and sedimentation to the ocean floor is also avoided. Therefore, drying up of the seashore and destruction of nature can be prevented, and conservation of the natural environment can be achieved.

On the other hand, even if the gravel layer becomes clogged due to trapped soil particles, removing the gravel and the trapped soil particles and replacing it with new gravel will restore the purification function of the gravel layer and achieve permanent purification. . If a permeable wall is also provided on the upstream side of the gravel layer, the more stable shape and function of the gravel layer can be maintained.

If there is a settling basin upstream of the gravel layer, coarse soil particles are removed in advance, and only fine particles need be separated by the gravel layer, which improves the efficiency of removing fine particles. By burying the tube in the gravel layer, the gaps between the gravel will become larger and the trapping function will be enhanced. If a water conduit or groove is provided that penetrates the permeable wall on the upstream side so as to actively guide running water into the gravel layer, the trapping effect will be increased.

If the gravel is packaged, it will be extremely easy to replace it. The same function can be achieved by using water-permeable pine instead of the gravel described above.

[Brief explanation of drawings]

Figure 1 is a vertical cross-sectional view of a river in which a filter structure is installed, to which the method of filtering soil particles contained in river water of the present invention is applied, and Figure 2 shows a permeable wall installed on the upstream and downstream sides of the gravel layer. Fig. 3 is a longitudinal cross-sectional view when a settling basin is provided upstream of the gravel layer, Fig. 4 is a view taken along the - line in Fig. 3, and Fig. 5 is a longitudinal cross-sectional view of the gravel layer. A schematic diagram of a filter structure with a pipe buried inside it, Figure 6 is a schematic diagram of a filter structure with a water conduit pipe installed, and Figure 7 is a filter structure in which a group of gravel is packaged. Schematic diagram of
Figure 8 is a schematic diagram of a filter structure using a permeable material instead of gravel, Figure 9 is a partial external view of an example of a frame dam used as a permeable wall, and Figures 10 to 12 are gravel This is a graph of field verification test data comparing the amount of soil particles contained in running water collected from before and after the layer. 1...river, 2...running water, 3...gravel layer, 3a...
...upstream side, 3b...downstream side, 4...gravel, 5,5A
...Transparent wall (weir, concrete wall, frame dam), 1
1...Sand basin, 12...Pipe body (vinyl chloride pipe),
12a... End face, 13... Water-permeable material (water-permeable pine),
14...Water pipe, 15...Water permeable material (water permeable pine),
18...Soil particles, h...Normal water level.

Claims (1)

[Claims] 1. Constructing a gravel layer higher than the normal water level in a river,
A weir is formed with a permeable wall to stabilize the shape of the gravel layer, and is installed on the downstream side of the gravel layer, and while the flowing water is flowing through the gravel layer, soil particles in the flowing water are separated, and the gravel layer is A method for filtering soil particles contained in river water, which removes gravel and trapped soil particles and replaces them with new gravel when the inside becomes clogged. 2. The method for filtering soil particles contained in river water according to claim 1, characterized in that a permeable wall is also provided on the upstream side of the gravel layer. 3. In claim 1 or claim 2, a settling basin with a wider river width is provided upstream of the gravel layer, and running water from which coarse soil particles have been removed in the settling basin is allowed to flow into the gravel layer. A method for filtering soil particles contained in river water, characterized by: 4 In the gravel layer, the end surface is covered with a water-permeable material,
4. A method for filtering soil particles contained in river water according to any one of claims 1 to 3, characterized in that a pipe body that prevents the intrusion of gravel is buried. 5. A water conduit pipe or groove for guiding flowing water into the gravel layer is provided through the permeable wall located on the upstream side, and the passage in the flow direction actively directs the flowing water into the gravel layer. 3. The method for filtering soil particles contained in river water according to claim 2, characterized in that the soil particles are guided. 6. The method for filtering soil particles contained in river water according to any one of claims 1 to 5, characterized in that the gravel is packaged to facilitate replacement of the gravel. 7. The method for filtering soil particles contained in river water according to any one of claims 1 to 6, characterized in that a water-permeable material is used in place of the gravel.