JP7614606B2 - Flowing object capture structure and method for installing the flowing object capture structure - Google Patents

Description

Application of Article 30, Paragraph 2 of the Patent Act Shima Takeji and Narumi Masatoshi have disclosed the flow-off capture structure and the installation method of the flow-off capture structure invented by Shima Takeji and Narumi Masatoshi on pages 327 and 328 of the Abstracts of the 2020 Erosion Control Society Research Presentation Meeting.

This invention relates to a drift material capture structure and a method for installing a drift material capture structure, and in particular to a drift material capture structure and a method for installing a drift material capture structure that are retrofitted to an existing sabo dam.

Erosion control dams are known as structures used to prevent landslides in mountain streams. Erosion control dams allow water to pass through while capturing downstream debris such as sediment, gravel and driftwood carried along by debris flows and floods, thus protecting conservation targets downstream.

However, in recent years, sabo dams alone have been unable to capture the large amounts of runoff caused by the effects of increasingly large typhoons and floods, and there have been cases where runoff that has flowed down or overflowed the sabo dams has reached conservation targets downstream.

To deal with such cases, there is a conventional method of installing a capture body in the water passage section of a sabo dam (Patent Document 1).

Figure 13 shows a front view and a side view of a conventional dam, and Figure 14 is a perspective view of the dam shown in Figure 13 as seen from upstream.

Referring to these figures, the dam 70 comprises a main body 71 and a capture body 72. The main body 71 is constructed, for example, from concrete, with its bottom buried in the ground, and is constructed so as to extend along the width of the river so as to cross the river.

A water passage section 73 is formed at the upper end of the main body 71 near the center along the width of the river, with the upper end being lower than the surrounding area. The water passage section 73 is formed to collect running water flowing from upstream near the center of the main body 71 and direct it downstream.

The trapping body 72 traps driftwood flowing from the upstream of the river and allows the flowing water to pass through, and is provided on the upstream wall 74 of the main body 71 along the width direction of the river. The trapping body 72 has one beam 75 extending along the width direction of the main body 71 (the width direction of the river) and multiple columns 76 connected at predetermined intervals along the extension direction of the beam 75. The beam 75 and the columns 76 are formed, for example, from steel pipes. The columns 76 have a first leg 76a and a second leg 76b. The upper end of the first leg 76a is joined to the beam 75 by welding or the like. The upper end of the second leg 76b is joined to the longitudinal center of the first leg 76a by welding or the like.

When installing the capture body 72, the flanges at the lower ends of the first leg 76a and the second leg 76b of the capture body 72, which is suspended by a crane or the like, are passed through the anchor bolts embedded and fixed in the upstream wall 74, and the capture body 72 is fixed in place with nuts.

In addition, there is another embodiment of a fluid capture structure that is composed of a fluid capture body installed in the water-beating section downstream of the main dam, which is a sabo dam (Patent Document 2).

Figure 15 is a schematic cross-sectional view showing a conventional fluid capture structure in use.

Referring to the figure, a fluid capture structure 80 is provided downstream of a main dam 81, which is an erosion control dam. Downstream of the fluid capture structure 80 is a secondary dam 83, which is a downstream erosion control dam that has basically the same configuration as the main dam 81.

The main bank 81 is made of, for example, concrete and has a water passage section 84 formed around the center of the width direction perpendicular to the flowing water direction to allow the flowing water 91 to pass through. A flat water beating section 86 made of, for example, concrete is formed on the riverbed downstream of the main bank 81 to protect against scouring by the flowing water 91 falling from the main bank 81 (water passage section 84). A fluid capture body 82 is installed above the riverbed contact section 87 (the point where the falling flowing water 91 is expected to reach the riverbed) of the flowing water 91 falling from the main bank 81 in the water beating section 86, constituting a fluid capture structure 80.

The fluid object capture body 82 is mainly composed of a capture member 88 that captures fluid objects 92 such as driftwood and gravel, and a support member 89 that fixes the capture member 88 to the water beating section 86 and supports the capture member 88 against the impact of the fluid objects 92 falling and the load of the accumulated flowing objects 92, and is made of materials and structures such as steel and wood that have a strength sufficient to withstand external forces such as the impact of the fluid objects 92 colliding with the flowing water 91 and the load of the accumulated fluid objects 92. The capture member 88 captures the falling fluid objects 92 and the fluid objects 92 that are carried along with the flowing water 91 after falling, by separating them from the flowing water 91. The support member 89 is a steel platform that is detachably fixed to the water beating section 86 using anchor bolts.

JP 2018-127880 A JP 2019-90307 A

However, the capture body 72 used in the above-mentioned dam 70 and the fluid capture body 82 used in the fluid capture structure 80 are both installed underwater (within the water flow cross section), and their installation could change the water depth inside the sabo dam. Therefore, construction required recalculation of the water depth, and depending on the results of the recalculation, it was necessary to reconstruct the existing sabo dam.

Furthermore, the capture body 72 is made of steel pipes, and the fluid capture body 82 is made of steel or wood, making it difficult to transport and install using human power alone. In other words, their transportation and installation requires vehicles such as cars or helicopters, heavy construction equipment such as cranes, and the construction of work roads to allow vehicles and heavy equipment to enter, which is not economical. Furthermore, these are not suitable for installation on erosion control dams built on land with poor accessibility where it is difficult for vehicles and heavy equipment to enter.

This invention was made to solve the above problems, and aims to provide a lightweight, easy-to-install flow-through capture structure whose capture body does not block the downstream water flow cross section.

In order to achieve the above-mentioned object, the invention described in claim 1 is a flow capture structure for capturing flow that overflows the main bank of a sand-control dam, comprising a capture body installed in the space above the forecourt protection work downstream of the main bank and below the water passage section of the main bank , and a guide fluid that slopes diagonally downward from the lower part of the water passage section toward the capture body and guides the flow to the capture body, the capture body being permeable to flowing water and capable of capturing the flow , and the guide fluid having its lower end located downstream of the upper end of the capture body .

With this configuration, the trapping body does not block the water flow cross section on the downstream side. Also, the flowing matter, whose long side is aligned with the water flow direction, is likely to roll over when it moves from the water guide to the trapping body. Furthermore, there is a portion between the water passage and the trapping body where the inclination angle is gentler than the falling angle of the flowing water.

The invention described in claim 2 is a flow capture structure for capturing flow that overflows the main embankment of a sand-control dam, comprising a capture body installed in the space above the forecourt protection work downstream of the main embankment and below the water passage section of the main embankment, and a guide fluid that slopes diagonally downward from the lower part of the water passage section toward the capture body and guides the flow to the capture body, the capture body is permeable to flowing water and capable of capturing the flow, the inclination angle of the guide fluid is gentler than the inclination angle of the main embankment, and the inclination angle of the capture body is gentler than the inclination angle of the guide fluid.

With this configuration, the trapping body does not block the water flow cross section on the downstream side. Also, the flowing matter, whose long side is aligned with the water flow direction, is likely to roll over when it moves from the water guide to the trapping body. Furthermore , there is a portion between the water passage and the trapping body where the inclination angle is gentler than the falling angle of the flowing water.

The invention described in claim 3 is the same as the invention described in claim 1 or 2, in which the capture body and the fluid guide have a flexible network structure.

This configuration results in a lightweight and inexpensive capture body and fluid guide.

The invention described in claim 4 is the configuration of the invention described in any one of claims 1 to 3, further comprising at least one capture body fixing member, which is installed on the side wall revetment of the front yard protection work and supports the capture body on the side wall revetment.

When configured in this way, construction can be carried out using existing structures.

The invention described in claim 5 is the same as the invention described in claim 4, in which the capture body is configured to be detachable from the side wall revetment.

This configuration makes it easy to replace the trap.

The invention described in claim 6 is the same as the invention described in claim 3, in which at least one of the capture body and the fluid guide further includes a tension adjustment member.

In this configuration, the spatial position of the capture body or fluid guide is stabilized by adjusting the tension.

The invention of claim 7 is a method for installing a flow-off capture structure in a sabo dam, comprising the steps of: drilling a plurality of first insertion holes in a side wall revetment of a forecourt protection work; drilling a plurality of second insertion holes in each of a lower part of a water passage part in a downstream slope of a main bank of the sabo dam and in the side wall revetment; injecting resin into each of the first insertion holes into which a first fixing member made of a lightweight part such as an anchor bolt is inserted and into each of the second insertion holes into which a second fixing member made in the same manner as the first fixing member is inserted, thereby fixing each of the first fixing member and the second fixing member; and fixing the first fixing member and the second fixing member to each of the first fixing member and the second fixing member by inserting a resin into each of the first insertion holes into which a first fixing member made of a lightweight part such as an anchor bolt is inserted and into each of the second insertion holes into which a second fixing member made in the same manner as the first fixing member is inserted. The method includes the steps of installing a capture body consisting of a wire rope net-like structure in the space above the vestibule protection work via each of the first fixing members, and installing a fluid guide consisting of a wire rope net-like structure via each of the second fixing members so that it slopes diagonally downward from the lower part toward the capture body, and the step of installing the fluid guide includes the steps of fixing the horizontal wire rope to the side wall revetment via each of the second fixing members, fixing the upper end of the vertical wire rope to the lower part of the water passage section via each of the second fixing members, and connecting the lower end of the vertical wire rope to the horizontal wire rope .

When configured in this way, all that is required for installation is lightweight materials and existing structures.

As explained above, in the invention described in claim 1, the trapping body does not block the water flow cross section on the downstream side, so there is no need to recalculate the water depth during construction or remodel the existing structure. Also, the downstream material, whose long side runs along the water flow direction, is prone to tipping over when moving from the guiding fluid to the trapping body. Furthermore, a portion is created between the water passage section and the trapping body with a gentler inclination angle than the falling angle of the flowing water, improving the trapping rate of the downstream material.

In the invention described in claim 2, the trapping body does not block the cross section of the water flow on the downstream side, so there is no need to recalculate the water depth during construction or remodel the existing structure. Also, the downstream material, whose long side runs along the water flow direction, is prone to tipping over when moving from the guiding fluid to the trapping body. Furthermore , a portion is created between the water passage section and the trapping body with a gentler inclination angle than the falling angle of the flowing water, improving the trapping rate of the downstream material.

The invention according to claim 3 has the same effects as the invention according to claim 1 or 2, and in addition, the capture body and fluid guide are lightweight and inexpensive, so that they can be transported and installed manually, and are economical.

The invention described in claim 4 has the same effect as any of the inventions described in claims 1 to 3, but in addition, since construction is performed using an existing structure, there is no need to remodel the existing structure or acquire new land for construction, which is economical and shortens the construction period. In addition, the support state of the capture body is stable.

The invention described in claim 5 has the same effect as the invention described in claim 4, and is therefore easier to maintain because the trapping body can be easily replaced.

The invention described in claim 6 has the same effect as the invention described in claim 3, but also improves the capture rate of the flowing matter by stabilizing the spatial position of the capture body or the fluid guide through tension adjustment.

The invention described in claim 7 requires only lightweight materials and existing structures for installation, so the materials required for installation can be transported and constructed using only human labor, making it an economical installation method that can shorten construction time.

1 is a plan view showing a flow-off capture structure according to a first embodiment of the present invention installed on a sabo dam. FIG. 2 is a right side schematic view of the flow-off capture structure shown in FIG. 1 installed on a sabo dam. FIG. FIG. 2 is a plan view showing the state in which the trapping body shown in FIG. 1 is installed on a sabo dam. FIG. 4 is an enlarged view of the “X” portion shown in FIG. 3 . 4 is an enlarged schematic diagram of the VV line shown in FIG. 3 . FIG. FIG. 2 is a plan view showing the fluid-guiding device shown in FIG. 1 installed in a sabo dam. FIG. 7 is an enlarged view of a portion “Y” shown in FIG. 6 . FIG. 7 is an enlarged view of a portion “Z” shown in FIG. 6 . 7 is an enlarged schematic diagram of the IX-IX line shown in FIG. 6 . 2 is a schematic diagram showing a process of installing the flow-off capture structure shown in FIG. 1. 2 is a schematic diagram showing a process of capturing a flowing-down object by the flowing-down object capturing structure shown in FIG. 1 . 2 is a schematic diagram showing a process in which a flowing object is overturned by the flowing object capturing structure shown in FIG. 1 . FIG. 1A and 1B are front and side views of a conventional dam. FIG. 14 is a perspective view of the dam shown in FIG. 13 as viewed from upstream. FIG. 1 is a schematic cross-sectional view showing a conventional fluid capture structure in use.

Figure 1 is a plan view of a drift material capture structure according to a first embodiment of the present invention installed on a sabo dam, and Figure 2 is a schematic right side view of the drift material capture structure shown in Figure 1 installed on a sabo dam.

Referring to these figures, a driftwood capture structure 1 is installed on a sabo dam 50.

The sabo dam 50 comprises a main levee 51 located on the upstream side of the river, a front yard protection work 52 located downstream of the main levee 51, and a secondary levee 53 located downstream of the front yard protection work 52.

The main embankment 51 is made of concrete, for example, and has a water passage section 54 formed around the center of the width perpendicular to the direction of the flowing water, which allows the flowing water to pass through. As will be described in detail later, the driftwood and other debris that cannot be captured by the main embankment 51 also passes through the water passage section 54 and flows downstream.

A flat water pounding section 55 made of, for example, concrete is formed on the riverbed downstream of the main embankment 51 to protect against scouring caused by flowing water falling from the water passage section 54. Together with a pair of side wall revetments 56a and 56b made of, for example, concrete, rising from both ends of the water pounding section 55 in the direction of the flowing water, this constitutes the forecourt protection work 52.

The secondary embankment 53 basically has the same configuration as the main embankment 51.

The flow-through object capture structure 1 comprises a capture body 10 and a fluid guide 30. The capture body 10 is installed in the space above the front yard protection work 52 and below the water passage section 54 of the main embankment 51, and is permeable to flow water and capable of capturing flow-through objects. With this configuration, the capture body 10 and the accumulated flow-through objects described below do not block the water passage cross section downstream, making it unnecessary to recalculate the water depth during construction and to remodel the existing erosion control dam 50. In particular, since the cross section of the water passage section 54 is not obstructed, it is unnecessary to raise the height of the area around the water passage section 54 (sleeve section) to provide a new cross section in the water passage section 54. In addition, since the hydrostatic pressure acting on the main embankment 51 does not change, it is unnecessary to increase the thickness of the main embankment 51. The configuration of the capture body 10 will be described in detail later.

The fluid guide 30 is also installed so that it slopes diagonally downward from the lower portion 59 of the water passage portion 54 toward the capture body 10. The details of the configuration of the fluid guide 30 and the effects of this configuration will be described later.

Figure 3 is a plan view showing the state in which the capture body shown in Figure 1 has been installed on a sabo dam, Figure 4 is an enlarged view of the "X" portion shown in Figure 3, and Figure 5 is an enlarged schematic view of the V-V line shown in Figure 3.

First, referring to FIG. 3, the capture body 10 is a net-like structure mainly consisting of a capture section 12 having a flexible net-like structure, in which a plurality of wire ropes 11 are arranged in a lattice shape and connected to each other at each intersection, and the capture section 12 is permeable to flowing water and can capture the flowing object. This configuration results in a lightweight and inexpensive capture body 10, which can be brought in and installed manually and is economical. In addition, since the external force acting on the capture body 10 can be distributed throughout the capture body 10, the individual components do not require high strength, and the cost of the capture body 10 is reduced. Furthermore, since the diameter of each component of the capture section 12 is small and the contact area with water in the capture section 12 is small, and the flowing water does not hit the captured flowing object as described below, there is no need to consider water pressure when installing the capture body. In addition, there is no risk of the captured flowing object hitting the flowing water and flowing out again.

The mesh intervals _D1 and _D2 of the trapping section 12 shown in Figures 1 and 2 are set to be smaller than 1/√5 of the expected length of the flowing object, which will be described later. For example, in the trapping body 10, the expected length of the flowing object is set to 5 m, and _D1 and _D2 are set to 2 m, which is a round number equal to or smaller than 2.2 m. The effect of this configuration will be described later.

Next, referring to FIG. 4, the wire rope 11a in the horizontal direction (perpendicular to the direction of the flowing water) and the wire rope 11b in the vertical direction (direction of the flowing water) cross each other in a plan view, and are connected at the intersection point using a cross clip 13. A turnbuckle 15a serving as a tension adjustment member is connected to one end 14a of the wire rope 11a. The effect of this configuration will be described later. A turnbuckle 15a and a shackle 17a are attached to one end 14a of the wire rope 11a. Meanwhile, a shackle 17b is attached to the other end 16a.

A capture body fixing member (first fixing member) 20a, which is composed of lightweight parts, an anchor bolt 21 and a metal fixing plate 22, is installed on the top end 57a of the side wall revetment 56a of the front yard protection structure 52. A capture body fixing member 20b, which has the same structure as the capture body fixing member 20a, is also installed at a position laterally opposite the capture body fixing member 20a on the top end 57b of the side wall revetment 56b. The wire rope 11a can be freely attached and detached to each of the capture body fixing members 20a and 20b via shackles 17a and 17b.

Next, referring to FIG. 5, one end (downstream end) 14b of the vertical wire rope 11b is connected to a turnbuckle 15b as a tension adjusting member. One end 14b and the other end (upstream end) 16b of the wire rope 11b via the turnbuckle 15b are connected to each of the horizontal wire ropes 11c and 11d via three-way clips 18a and 18b, respectively, so that the wire rope 11b intersects with the horizontal wire ropes 11c and 11d in a T-shape in plan view.

Referring to FIG. 3, the other wire ropes 11 are also similar in configuration to the wire rope 11a shown in FIG. 4, with the wire rope 11b shown in FIG. 5, with the wire rope 11b arranged in the vertical direction. In addition, capture body fixing members 20 having the same configuration as the capture body fixing members 20a and 20b shown in FIG. 4 are installed at the locations corresponding to the positions of the other horizontal wire ropes 11 on the side wall revetments 56a and 56b. Therefore, the capture body 10 is configured to be detachable from the side wall revetments 56a and 56b. With this configuration, the capture body 10 can be easily replaced, resulting in excellent maintainability.

In addition, each of the capture body fixing members 20 is installed on each of the side wall revetments 56a and 56b to support the capture body 10 at the side wall revetments 56a and 56b. With this configuration, construction is carried out using the side wall revetments 56a and 56b, which are existing structures, so there is no need to renovate the existing structure (sabo dam 50) or purchase new land to construct the capture body 10, which is economical and shortens the construction period. In addition, the support state of the capture body 10 is stable.

Figure 6 is a plan view showing the fluid guide shown in Figure 1 installed in a sabo dam, Figure 7 is an enlarged view of the "Y" part shown in Figure 6, Figure 8 is an enlarged view of the "Z" part shown in Figure 6, and Figure 9 is an enlarged schematic view of the IX-IX line shown in Figure 6.

First, referring to FIG. 6, the flow guide 30 is a net-like structure mainly consisting of a flexible net-like structure of a flow guide section 32, which is made up of a plurality of wire ropes 31 arranged in a lattice pattern and connected at each intersection. The flow guide section 32 temporarily receives the flowing material while allowing the flowing water to pass through. This configuration results in a lightweight and inexpensive flow guide 30, which can be brought in and installed manually and is economical. Furthermore, since the external force acting on the flow guide 30 can be distributed throughout the entire flow guide 30, the individual components are not required to have high strength, and the cost of the flow guide 30 is reduced. Furthermore, since the diameter of each component of the flow guide section 32 is small and the contact area of water in the flow guide section 32 is small, there is no need to consider water pressure when installing the flow guide 30.

1 and 2, the position of the flow guide 30 is as described above, so that the flow-down material temporarily received by the flow guide 30 is guided to the capture body 10 along the inclination of the flow guide 30. The effects of this configuration will be described later. The mesh intervals _d1 and _d2 of the flow guide section 32 are also set to 1/√5 of the expected length of the flow-down material, which will be described later, and are each set to 2 m. The effects of this configuration will also be described later.

Next, referring to FIG. 7, the horizontal wire rope 31a and the vertical wire rope 31b cross each other in a plan view, and are connected at the intersection point using a cross clip 33. A turnbuckle 35a is connected to one end 34a of the wire rope 31a as a tension adjustment member. The effect of this configuration will be described later. One end 34a and the other end 36a of the wire rope 31a via the turnbuckle 35a are connected to each of the vertical wire ropes 31c and 31d via three-way clips 38a and 38b, respectively, so that the wire rope 31a crosses each other in a T-shape in a plan view.

Next, referring to FIG. 8, the horizontal wire rope 31e and the vertical wire rope 31c intersect in a T-shape in plan view and are connected at the intersection using a three-way clip 38c. A turnbuckle 35b serving as a tension adjustment member is also connected to one end 34b of the wire rope 31e. A turnbuckle 35a and a shackle 37a are attached to one end 34b of the wire rope 31e. Meanwhile, a shackle 37b is attached to the other end 36b.

A fluid guide fixing member (second fixing member) 40a, which is composed of lightweight parts, an anchor bolt 41 and a metal fixing plate 42, is installed on the top end 57a of the side wall revetment 56a of the front yard protection structure 52. A fluid guide fixing member 40b, which has a similar structure to the fluid guide fixing member 40a, is also installed at the top end 57b of the side wall revetment 56b in a position laterally opposite the fluid guide fixing member 40a. The wire rope 31e can be freely attached and detached to each of the fluid guide fixing members 40a and 40b via shackles 37a and 37b.

Next, referring to Figures 9 and 2, one end (lower end) 34c of the vertical wire rope 31b is connected to the horizontal wire rope 31e and wire rope 31b via a three-way clip 38c so that the wire ropes intersect in a T-shape in plan view. A shackle 37c is attached to the other end (upper end) 36c of the wire rope 31b.

A fluid guide fixing part 40c having a similar structure to the fluid guide fixing part 40a is installed in the lower part 59 of the water passage part 54 on the downstream slope 58 of the main bank 51. The wire rope 31b can be freely attached and detached to the fluid guide fixing part 40c via the shackle 37c.

Referring to FIG. 6, the other wire ropes 31, except for the wire rope 31e shown in FIG. 8, have the same configuration as the wire rope 31a shown in FIG. 7, and the other wire ropes 31 arranged vertically have the same configuration as the wire rope 31b shown in FIG. 9. In addition, capture body fixing members 40 having the same configuration as the fluid guide fixing member 40c shown in FIG. 9 are installed at each of the locations on the slope 58 corresponding to the positions of the other vertical wire ropes 11. Therefore, the fluid guide 30 is configured to be freely detachable from the side wall revetments 56a, 56b and the slope 58. With this configuration, the fluid guide 30 can be easily replaced, resulting in excellent maintainability.

Furthermore, each of the fluid guide fixing members 40 is installed on each of the side wall revetments 56a, 56b and the slope 58 to support the fluid guide 30 at the side wall revetments 56a, 56b and the slope 58. With this configuration, construction is carried out using the side wall revetments 56a, 56b and the slope 58, which are existing structures, so there is no need to renovate the existing structure (sabo dam 50) or purchase new land for the construction of the fluid guide 30, which is economical and shortens the construction period. In addition, the support state of the fluid guide 30 is stable.

Furthermore, the fluid guide 30 is installed so that its installation width is wider than the width of the water passage section 54, so that the flowing water and debris passing through the water passage section 54 (described later) tend to flow to the top of the fluid guide 30.

All of the components constituting the capture body 10, capture body fixing member 20, fluid guide 30 and fluid guide fixing member 40 described so far have been treated with hot-dip galvanizing or the like to prevent corrosion.

Figure 10 is a schematic diagram showing the installation process of the flow-through capture structure shown in Figure 1.

First, referring to FIG. 10 (1), in the sabo dam 50, a number of first insertion holes 23 are drilled in the side wall revetments 56a and 56b of the forecourt protection work 52 according to the number of capture body fixing members 20 to be installed. In addition, a number of second insertion holes 43 are drilled in the lower part 59 of the water passage part 54 on the downstream slope 58 of the main dam 51 and in each of the side wall revetments 56a and 56b according to the number of fluid guide fixing members 40 to be installed.

Next, with the anchor bolt 21 of the capture body fixing member 20 inserted into the first insertion hole 23 and the anchor bolt 41 of the fluid guide fixing member 40 inserted into the second insertion hole 43, epoxy resin is injected into each of the first insertion hole 23 and the second insertion hole 43 to fix the capture body fixing member 20 and the fluid guide fixing member 40 together.

Next, referring to FIG. 10 (2), the capture body 10 is installed between the top end 57a of the side wall revetment 56a and the top end 57b of the side wall revetment 56b, which is the space above the forecourt protection work 52, via each of the capture body fixing members 20. At this time, the tension is adjusted by the turnbuckle 15 shown in FIG. 3 so that the capture body 10 does not bend more than necessary. With this configuration, the tension adjustment makes it difficult for the components of the capture body 10 to open up, and the spatial position of the capture body 10 is stabilized when it comes into contact with the flowing material described below, improving the capture rate of the flowing material.

Finally, referring to FIG. 10 (3), the guide 30 is installed so as to be inclined obliquely downward from the lower portion 59 of the water passage portion 54 toward the trapping body 10 via each of the guide fixing members 40. The inclination angle θ of the guide 30 is set to about 45°, and the lower end of the guide 30 is located downstream of the upper end of the trapping body 10. With this configuration, an overlapping portion is formed between the guide 30 and the trapping body 10, and no gap is formed between the guide 30 and the trapping body 10, improving the capture rate of the flowing object. At this time, the tension is adjusted by the turnbuckle 35 shown in FIG. 6 so that the guide 30 does not bend more than necessary. With this configuration, the tension adjustment makes it difficult for the members of the guide 30 to open up, and the spatial position of the guide 30 when it comes into contact with the flowing object, which will be described later, is stabilized, improving the capture rate of the flowing object.

In this way, the installation process of the drift material capture structure 1 is completed. With this configuration, all that is needed to install the drift material capture structure 1 are lightweight items such as wire ropes and anchor bolts, as well as existing structures, so that the materials needed for installation can be transported and constructed using only human power. In other words, there is no need for vehicles for transporting the materials, heavy machinery for construction, roads for accessing these, land for the installation site, or reconstruction of the erosion control dam 50, making this an economical installation method that is expected to shorten the construction period.

Figure 11 is a schematic diagram showing the process of capturing drift material using the drift material capture structure shown in Figure 1.

Referring to the figure, the flowing water (water, fine soil, etc.) 61 and drifting debris (mainly driftwood) 62 that pass through the water passage section 54 and overflow the main embankment 51 flow to the top of the guide 30. Here, the installation position of the guide 30 is as shown in Figure 10 (3), so the inclination angle θ of the guide 30 is gentler than the falling angle of the flowing water 61 that falls in a parabola after passing through the water passage section 54. In other words, since the guide 30 is installed so as to intersect with the falling trajectory of the flowing water 61, the guide 30 creates a portion between the water passage section 54 and the capture body 10 where the inclination angle is gentler than the falling angle of the flowing water 61. Therefore, the flowing water 61 that passes through the water passage section 54 passes through the guide fluid 30 and falls in a parabola without directly colliding with the capture body 10, but the flowing object 62 comes into contact with the guide fluid 30 before its own inclination becomes equal to the falling angle of the flowing water 61 from the start of the inclination, so it does not slip through the mesh of the guide fluid 30, but instead inclines along the inclination of the guide fluid 30 and is temporarily received by the guide fluid 30.

The flowing matter 62 separated from the flowing water 61 in this way is guided to the capture body 10 by sliding down the guide fluid 30 due to the inclination of the guide fluid 30. The flowing matter 62 is guided to the capture body 10 at a gentler incline along the incline of the guide fluid 30 than when it falls on the flowing water 61. In other words, the flowing matter 62 is guided to the capture body 10 in a position that makes it difficult for it to slip through the mesh of the capture body 10.

The trapping body 10 is supported by the side wall revetments 56a and 56b and has a gentler slope than the guide 30, so the propulsion of the flowing material 62 guided to the trapping body 10 gradually weakens, and the flowing material 62 stops and is captured within the trapping body 10. This configuration improves the capture rate of the flowing material 62. In addition, the falling distance of the flowing material 62 is shortened, so the impact on the guide 30 and the trapping body 10 is reduced, and the guide 30 and the trapping body 10 are less likely to be damaged. In particular, the flowing material 62 does not collide directly with the trapping body 10 through the guide 30, so the load on the trapping section 10 is reduced. Furthermore, the flowing material 62 captured and accumulated in the trapping body 10 does not block the water flow cross section on the downstream side, so there is no need to recalculate the water depth during construction or remodel the existing structure.

Figure 12 is a schematic diagram showing the process in which the drift material is overturned by the drift material capture structure shown in Figure 1.

First, referring to Fig. 12 (1), driftwood-based drift material 62 reaches the guiding fluid 30 with its long side aligned with the flow direction, and slides down the guiding fluid 30 in that orientation. As described above, the mesh intervals _d1 and _d2 of the guiding portion 32 are set to be equal to or less than L/√5 with respect to the expected length L of the drift material 62. That is, the mesh intervals _d1 and _d2 are equal to or less than 1/2 of the expected length L of the drift material 62, and according to Pythagoras' theorem, the length of the diagonal of two parallel meshes is _d1 : _2d2 = √5:1:2. Therefore, when the drift material 62 slides down the guiding fluid 30, at least two points of the drift material 62 always contact the guiding portion 32. With this configuration, the drift material 62 is unlikely to slip through the meshes of the guiding portion 32 and fall while sliding down the guiding fluid 30.

12(1), in the case where the flowing down object 62 slides down the flow guide 30 in the horizontal direction, if the mesh intervals _d1 and _d2 are set to L/2, at least two points of the flowing down object 62 always contact the flow guide portion 32, and the flowing down object 62 slides down stably. Therefore, it is preferable to set the mesh intervals _d1 and _d2 to L/2 or less, and more preferable to set them to L/√5 or less.

The flow-down material 62 guided from the flow guide 30 to the capture body 10 in this way collides with the lateral wire rope 31 of the flow guide section 32 or the lateral wire rope 11 of the capture section 12 while moving from the flow guide 30 to the capture body 10. Then, due to the impact of the collision, it rolls over while being supported by the lateral wire rope 31 of the flow guide section 32, which is located above the wire rope 31 or 11 that collided.

Next, referring to FIG. 12(2), the overturned flowing object 62 rolls in the trapping body 10 and eventually stops and is captured in the trapping body 10. As described above, the mesh intervals _D1 and _D2 of the trapping section ₁₂ are also set to be L/√5 with respect to the expected length L of the flowing object 62. Therefore, the mesh intervals _D1 and D2 are also set to be less than 1/2 of the expected length L of the flowing object 62, and according to Pythagoras' theorem, the diagonal lengths of the two parallel meshes are: _D1 : _2D2 =√5:1:2, so that the flowing object 62 rolls in the trapping body 10 with at least two points always in contact with the trapping section 12. With this configuration, the flowing object 62 is less likely to slip through the meshes of the trapping section 12 and fall while rolling in the trapping body 10. In addition, the capture rate of the flowing object 62 is improved.

In addition, when the flowing down object 62 rolls sideways in the trapping body 10, if the mesh intervals _D1 and _D2 are set to L/2, like the mesh intervals _d1 and _d2 , at least two points of the flowing down object 62 are always in contact with the trapping part 12, and the flowing down object 62 rolls stably. Therefore, it is preferable to set the mesh intervals _D1 and _D2 to L/2 or less, and more preferably to L/√5 or less.

In the first embodiment, the flow-down object capture structure includes a capture body and a fluid guide, but it may also be composed of only a capture body.

In addition, in the first embodiment, the capture portion of the capture body and the flow guide portion of the fluid guide are constructed using wire ropes, but they may be constructed using other materials. For example, they may be constructed using a chain, or an elastic chain in which rubber is placed between the chain links and the entire chain is covered with rubber.

Furthermore, in the first embodiment described above, the diameter of each wire rope is not specifically set, but it may be set within the range of 16 mm to 30 mm depending on the width of the revetment to be installed and the planned amount of driftwood to be captured.

In addition, in the first embodiment described above, the capture body has a flexible mesh structure with a specific configuration, but other configurations and structures are also possible as long as it is permeable to flowing water and can capture the flowing matter. For example, it may be a steel plate with drainage holes or slits, a lattice of metal rods, a permeable screen, etc.

In addition, in the first embodiment described above, the fluid guide has a flexible net-like structure with a specific configuration, but it may be anything that slopes diagonally downward from the bottom of the water passage part toward the trapping body and can guide the flowing material to the trapping body. For example, it may be a slide-like structure that is not permeable to running water.

Furthermore, in the first embodiment described above, the guide fluid is installed at a specific inclination angle, but it may be set to an angle of approximately 45° or more, and even better, it may be set to the average gradient up to the point where the trajectory of the flowing water intersects with the guide fluid.

Furthermore, in the first embodiment described above, the lower end of the guide fluid is located downstream of the upper end of the trapping body, and the guide fluid is installed so that there is an overlap between the guide fluid and the trapping body, but the lower end of the guide fluid may be located upstream of the upper end of the trapping body as long as the flowing matter can be guided to the trapping body.

In addition, in the first embodiment described above, the wire ropes are arranged in a lattice pattern in the capture section and the flow guide section, but they may be arranged in other patterns, such as a flowing cross or diagonal, as long as the mesh spacing is set to 1/2 or less of the expected length of the flowing material, more preferably 1/√5 or less.

Furthermore, in the first embodiment described above, the mesh spacing of the capture section and the flow guide section was set to a specific dimension, but it may be set to 1/2 or less of the expected length of the flowing object, more preferably 1/√5 or less, and the smaller the mesh spacing, the more likely the flowing object will be captured.

Furthermore, in the first embodiment above, the capture body was installed through the side wall revetment, but it is sufficient if it is installed in the space above the front yard protection work and below the water passage section.

In addition, in the first embodiment described above, the capture body was supported by multiple capture body fixing members installed on the side wall revetment, but other fixing members may be used in combination as long as the capture body is supported by at least one capture body fixing member. Also, the capture body may be supported only by fixing members other than the capture body fixing member, or may be supported at a location other than the side wall revetment.

Furthermore, in the first embodiment described above, the capture body fixing member and the fluid guide fixing member are fixed using a specific resin, but they may be fixed by other means.

Furthermore, although the capture body was configured to be detachable from the side wall revetment, it may also be fixed to the side wall revetment.

Furthermore, while the guide was designed to be detachable from the side wall revetment and the slope of the main bank, it may also be fixed to these.

Furthermore, although the capture body and the fluid guide are provided with turnbuckles as tension adjustment members, other members may be used as tension adjustment members. For example, a rubber link structure in which a buffer section made of rubber material that easily plastically deforms is inserted between the chain links may be used to tension a portion of the capture body or the fluid guide as a whole. The use of a rubber link structure can also provide a shock mitigation effect. Furthermore, it is sufficient that at least one of the capture body and the fluid guide is provided with a tension adjustment member, and furthermore, neither of them need be provided with a tension adjustment member.

1... Flowing object capture structure 10... Capture body 11, 11a, 11b... Wire rope 12... Capture portion 15a, 15b... Turnbuckle 20, 20a, 20b... Capture body fixing member (first fixing member)
21: Anchor bolt 23: First insertion hole 30: Fluid guide 31, 31a, 31b, 31c, 31d, 31e: Wire rope 32: Flow guide portion 35a, 35b: Turnbuckle 40, 40a, 40b, 40c: Fluid guide fixing member (second fixing member)
41...Anchor bolt 43...Second insertion hole 50...Sand control dam 51...Main embankment 52...Forest yard protection work 54...Water passage section 56a and 56b...Side wall revetment 57a and 57b...Top end 58...Slope 59...Lower part 61...Flowing water 62...Flowing object Furthermore, the same symbols in each figure indicate the same or corresponding parts.

Claims (7)

A flow-capturing structure for capturing flow-off material overflowing a main bank of a sabo dam,
A capture body is installed in the space above the front yard protection work downstream of the main bank and below the water passage part of the main bank ;
A guide fluid is provided which is inclined obliquely downward from the lower part of the water passage portion toward the trapping body and guides the flowing matter to the trapping body,
The capture body is permeable to flowing water and capable of capturing the flowing matter ,
The flow guide has a lower end located downstream of an upper end of the trapping body . A flow-capturing structure for capturing flow-off material overflowing a main bank of a sabo dam,
A capture body is installed in the space above the front yard protection work downstream of the main bank and below the water passage part of the main bank;
A guide fluid is provided which is inclined obliquely downward from the lower part of the water passage portion toward the trapping body and guides the flowing matter to the trapping body,
The capture body is permeable to flowing water and capable of capturing the flowing matter,
The inclination angle of the guide is gentler than the inclination angle of the main bank,
A flow-down object capture structure, wherein the inclination angle of the capture body is gentler than the inclination angle of the fluid guide. 3. The flow-down object capture structure according to claim 1 , wherein the capture body and the fluid guide have a flexible net-like structure. Further comprising at least one capture body fixing member;
The flow-down object capture structure according to any one of claims 1 to 3, wherein the capture body fixing member is installed on a side wall revetment of the front yard protection work to support the capture body on the side wall revetment. The drift trapping structure according to claim 4, wherein the trapping body is configured to be detachable from the side wall revetment. The flow-down capture structure according to claim 3, wherein at least one of the capture body and the fluid guide further comprises a tension adjustment member. A method for installing a flow-off capture structure in a sabo dam, comprising the steps of:
Drilling a plurality of first insertion holes in a side wall revetment of the front yard protection work;
drilling a plurality of second insertion holes in each of a lower portion of a water passage portion in a downstream side slope of a main bank of the sabo dam and in the side wall revetment;
a step of injecting resin into each of the first insertion holes into which a first fixing member made of a lightweight part such as an anchor bolt is inserted and into the second insertion holes into which a second fixing member made of the same structure as the first fixing member is inserted, thereby fixing the first fixing member and the second fixing member;
a step of installing a capture body consisting of a net-like structure using wire ropes in a space above the vestibule protection structure via each of the first fixing members;
and installing a fluid guide made of a net-like structure using wire ropes so as to be inclined obliquely downward from the lower part toward the trapping body through each of the second fixing members,
The step of installing the fluid guide includes the steps of fixing the horizontal wire rope to the side wall revetment via each of the second fixing members, fixing the upper end of the vertical wire rope to the lower part of the water passage portion via each of the second fixing members, and connecting the lower end of the vertical wire rope to the horizontal wire rope .

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