JP2011089250A - Method for accelerating flow-down of sediment accumulated in river and the like - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an environmentally-friendly, permanent and easy method for accelerating flow-down of sediment accumulated in a river and the like. <P>SOLUTION: A structure, which is made of a material such as a stone, a rock, concrete, iron, other metals and wood, is installed along a flow direction in a stream of water, so as to accelerate the flow-down of the sediment accumulated in an upstream place or that place. The structure is formed in a shape like a fence, a retaining wall, a colonnade composed of a pile and a column, or a bedrock, and fixed to the bottom of the water so as not to be deformed and displaced by the stream of the water. This method, which artificially reproduces a naturally applied action as-is, exerts its effect on any place where the stream of the water and the sediment of soil, sand, the stone, etc. exist. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for promoting the flow of sediment deposited in a river or the like.

  It can be said that it is natural that sediments such as soil, sand, stones and rocks accumulate on the riverbed, riverbank and riverbed in rivers, but depending on the location, the amount is too large, It is a cause of unnecessary riverbed rise and flooding during flooding. In the past, artificial mechanical forces such as civil engineering machines and ships have been used to remove these sediments.

  As a method of removing sand accumulated in the river, a method of installing a structure in the flow is also considered, but it has a more complicated structure than the present invention and lacks flexibility in installation location. (For example, see Patent Document 1).

  As an example similar to a structure according to the present invention, you may see a scene where piles or pillars are driven into a river flow. They are similar in appearance to the method according to the invention, but have a completely different intention from the method according to the invention. They are not intended to promote sediment flow, but to control water flow and weaken the flow force.

  In those piles and pillars, a considerable length of the vertical length protrudes from the water surface at normal water levels. This is because the part that protrudes into the air at normal water level is required to act at the time of water increase and weaken the water flow. In addition, these piles and columns are not considered for continuity in the direction of water flow. Attention is paid to increasing the spacing rather than continuity, with almost constant spacing.

  Sometimes you see piles and pillars under the surface of the water, but they are installed transversely to the flow of water and play a role in hindering the flow of water and sediment. In order to promote the flow of earth and sand as intended by the present invention, it is necessary to install them continuously in the direction of water flow with a certain length and no gap in the case of a small surface area such as a pile. there is.

  In other words, the conventional method of driving piles and pillars is not aimed at promoting sediment flow.

  Some of the methods of driving piles and pillars into the flow of water clearly state that the purpose is to stop the bottom of a river or to naturally deposit sediment (for example, see Patent Document 2).

JP-A-7-18640 JP-A-11-256548

  Conventionally, it takes a lot of time and money to remove sediment deposited in rivers. In addition, these works often have only temporary effects and are often repeated continuously. It has been desired to improve these problems in a permanent and inexpensive way.

  In order to improve this situation, we have devised an effective and inexpensive method that does not place excessive load on the environment by installing structures that mimic the action naturally found in rivers.

  The present invention promotes the flow of sediment deposited in rivers by installing structures made of hard materials along the direction of water flow, like stones and rocks in river flows. The

  The structure is shaped like a bowl, a retaining wall, a column with piles or columns, or a rock, so that it does not move, deform, or flow down even with water flow.

  As materials for structures, stones, rocks, concrete, iron, other metals, wood, and other materials that can be configured in the required shape and performance are selected after considering their service life.

  In natural rivers, earth and sand such as soil, sand, stones and rocks are always flowing along with water. Among them, hard and massive stones and rocks reinforce the strength of the water flowing nearby. The strengthened flow of water will cause the soil, sand and stones in the upstream of the stones and rocks and the places to flow down more quickly. Eventually, the places with stones and rocks will become deeper as the earth and sand flow down compared to other places.

Sediment accumulates continuously in the river, so if the sediment flows down and deepens in a place with stones or rocks, the sediment on the upstream or shore flows into the stones or rocks to fill it. And stones and rocks will flow down those sediments. In rivers where sediment, such as soil, sand, stones, and rocks, is deposited, the flow of sediment is promoted.
This action is accompanied by the flow of water and occurs in places where there are stones and rocks that are larger than the soil, sand or stones that flow down. In addition, this effect is small compared to the sediment flow caused by the water flow itself.

  In upstream areas of rivers, there are usually a lot of stones and rocks on the riverbed, but not all places in the flow have stones and rocks. Therefore, the depths around the stones and rocks, which are called corals, created by this action are also buried by the inflow of a large amount of sediment from the upstream when there is a large increase in water. However, since it is a force that is constantly generated in places where there are water currents and stones and rocks, when the water increase is completed, the stones and rocks will continue to make the earth and sand flow down and create a depth called reeds around.

  This effect is not so great. However, in places where there are stones and rocks larger than the flowing sediment, it is always added to the sediment flow by the water flow itself. Therefore, in a full concrete waterway or river that is in the same state as a large rock on the entire surface of the flow, the flow of sediment will increase, and most of the sediment will flow downstream when the water increases.

  This action becomes stronger as the stones and rocks are larger and the longer they are in the flow direction. As a result, phenomena such as deepening the bottom of the rocks and concrete revetments occur in the middle and downstream.

  The above phenomena seen in rivers are all the same effects that appear in various ways. This action becomes stronger as the surface area of stones and rocks in the water increases and the flow of water increases. This action is a force that is always generated where there is water flow and stones or rocks.

In rivers, the average amount of water is usually longer than the period of water increase, so even a small force can take a long time to deepen around stones and rocks.
After many sediments have accumulated in many rivers, the flow of water is finally determined, and the sediment is gradually discharged, creating various landscapes such as droughts, rough waters and rivers, creating a living environment for various organisms. Indicates that the flow of sediment during normal water flow is greater than the flow of sediment during flooding.

However, in natural rivers, the stones and rocks that cause these effects will eventually flow along with water, just like soil and sand.
In particular, in the middle and downstream, stones and rocks become smaller, and it is easy to flow down due to the flow of water. Therefore, there is little depth due to stones and rocks in the middle and downstream of the river, and the amount of sediment deposited tends to increase naturally.

  The present invention has the ability to flow down earth and sand by fixing a rigid structure made of hard material, a retaining wall shape, a columnar shape with pillars and piles, or a rock-like structure in a water flow. Keep it constant.

Since the method of the present invention does not require the structure to protrude from the surface of the water, it has the advantage that it does not obstruct the flow of water or sediment even when there is an increase in water. In addition, obstacles such as driftwood flowing down with water and earth and sand are less likely to interfere with the flow.
Since this structure can be made to look like natural stones and rocks, it can be said to be an extremely environmentally friendly method with little discomfort in the landscape.

  The method of the present invention mimics the action of natural water flow at normal water levels, so the effect will not be excessive. In other words, even if sediment is caused to flow down, it does not accumulate rapidly downstream. Sediment flows down gradually over a long period of time.

  Since the method of the present invention allows the earth and sand to flow down and deepen the place, it is also possible to form dredging in the river. It is not enough to install a structure according to the method of the present invention alone, but it is possible by installing multiple structures in association with each other. In this case, it is possible to provide a good habitat for many organisms such as insects and fish by devising the structure of the structure and considering its arrangement.

  The method of the present invention is useful for controlling the position of the water flow because it allows the sediment to flow down and deepen its location. Since the flow of water tends to be deep in the center of the flow, installing this structure will affect the position of the water flow in the riverbed, and the position of the core in the flow. Can be affected.

  The method of the present invention is effective wherever there is a stream of water and soil, sand or stone. Therefore, the effect can be expected not only in the upper and middle rivers, but also in the downstream areas and the coasts where water flows. In addition, the installation of this structure can be expected to be effective even when earth and sand close the river mouth at the river mouth of the river downstream.

  Since the structure according to the method of the present invention is simple in structure, it is flexible in its installation. When more effects are required, it is easy to install according to various situations, such as installing multiple rows of structures or increasing the length in the direction of water flow.

  The method of the present invention is flexible in the selection of materials and is simple in shape, so installation costs are low. In particular, when piles and pillars are installed in a columnar shape, the materials and installation costs are cheap.

It is explanatory drawing which installed the structure of the Example of this invention in the shape of a column. It is explanatory drawing which installed the structure of the Example of this invention in the shape of a bowl. It is explanatory drawing of the example which made the structure of the Example of this invention into the shape of a bowl and a column, and imitated each upper part in the shape of natural stone and rock. It is a top view of the example which forms a reed in the flow of a river by installing two or more structures of the example of the present invention in the shape of a retaining wall and a column. It is the top view which installed the structure of the example of the present invention in the shape of a rock. It is a top view of the example which moves the position of a fluid core with the structure of the Example of this invention.

Figure 1 shows an example of a structure according to the present invention installed in a middle river basin where sediment has accumulated.
In the middle stream of small and medium-sized rivers where sediment has accumulated, a concrete circular pillar (diameter 25 cm, length 3 m) is driven deep into the flow of water to form a columnar structure 1 with a length of 3 meters. . These columns need to be continuous as a whole, but there is no problem if they are partially spaced. The thickness and length of the pillars to be installed and the length of the continuous pillars are determined in consideration of various conditions in the river.
The flow direction of the river water is 5, and the normal water surface is 6.
The riverbed 7 as a result of a large amount of sediment flowing down from the upstream due to the increase in water gradually becomes deeper in the normal amount of water by the action of the column 1 which is a structure according to the present invention, and the upstream sediment is allowed to flow down, eventually the riverbed 8 It will change to.

  Fig. 2 shows an example in which the structure according to the present invention is installed in a bowl shape. Fig. 3 shows the structure of the method of the present invention in the shape of a bowl and a column, and the upper part of each structure is formed to look like natural stones and rocks. The relationship between water flow and earth and sand is the same as in Fig. 1 in both cases.

A columnar structure with pillars as in the example in Fig. 1 can be said to be easy to install, but it may not be possible to install in all locations such as rivers. In the upstream, there are many accumulated stones and rocks, and it is difficult to drive these columns. Even in locations with strong water flow, columnar structures are difficult to fix due to their low weight.
In these cases, the saddle-like structure shown in Fig. 2 or Fig. 3 is effective in solving each difficulty. In the case of a bowl, it becomes easier to fix due to the increase in weight, and the whole can be installed in a lump.

  The retaining wall-like structure like the structure 3 in the example of Fig. 4 forms a depth only on one side, so it can have the same function as a bank revetment or embankment. In addition, the formation of corals is facilitated because it can have the same form as the rock walls found in natural rivers.

The rock-like structure 4 in the example of Fig. 5 imitates the natural bedrock at the bottom of the river as seen in the upstream part of the river.
Sediment accumulation in rivers varies from river to river and location. In cases where it is difficult to install columnar, columnar, or retaining wall structures, it is possible to promote sediment flow by making the riverbed rock-like. In Fig. 5, the entire riverbed is shaped like a rock, but only a part can be rocked.

  Figure 6 shows an example of moving the center of the flow by installing a saddle-shaped structure in the center of the river. In the bent part on the left side of Fig. 6, the center of the water flow is moved to the center by continuously installing the structure 2 in the center of the river. This is an example of moving the flow that normally flows biased to the right bank (upper side of Fig. 6) to the center depending on the depth created by the bowl-shaped structure before the center of the flow touches the right bank.

1 columnar structure by the method of the present invention 2 bowl-shaped structure by the method of the present invention 3 retaining wall-shaped structure by the method of the present invention 4 bedrock-shaped structure by the method of the present invention 5 flow of water Direction 6 Normal water surface 7 River bed after water increase 8 River bed after earth and sand has flowed down due to effects of 1 or 2 9 Earth and sand deposited on river bed 10 Inside line of revetment or dike

Claims (3)

  It is characterized by installing and fixing a columnar structure made of hard materials, made of hard materials, or a columnar structure made of piles or columns, alone or in combination, along the direction of the flow of water. , A method to promote sediment flow.   A method for promoting the flow of earth and sand, characterized by embedding and fixing a rock-like structure made of hard material in the flow of water. A method for facilitating the flow of earth and sand, characterized in that the structure of claim 1 and the structure of claim 2 are combined and installed in a water flow.

Images