Sand control dam and capturing unit

Abstract

To provide a transmission type sand control dam in which a capturing function portion is unitized and an outflow of small-grain gravel such as fine soil and sand can be suppressed as necessary.SOLUTION: A sand control dam D is constructed by inserting a capturing unit 10 having a frame portion 11 and a plurality of horizontal beam members 20 into grooves 6a, 6b formed in a pair of side face portions 3a, 3b of a dam body 1. The capturing unit 10 is detachable, to improve workability and economy. A capturing auxiliary tool 40 consisting of a net body or the like is detachably attached to an upstream side of the capturing unit 10 as required. The capturing auxiliary tool 40 limits a size of objects passing through the capturing unit 10 to less than a predetermined size, to prevent fine soil and sand from flowing downstream.SELECTED DRAWING: Figure 10

Description

[Technical field]

[0001] The present invention relates to an erosion control dam intended to suppress the outflow of small-grained sand and gravel that flows out during a sweeping flow and to unitize the capture function parts, and in particular to an erosion control dam consisting of a capture unit which is a unitized capture function part and a concrete structure provided with an opening into which the capture unit can be installed. [Background technology]

[0002] Sabo dams have the function of slowing down the flow of water during floods and debris flows, and of holding back driftwood and debris to restrict their flow downstream, thereby minimizing damage to houses, facilities, roads, etc. Permeable sabo dams have slits in the dam body to allow water to pass through, so they do not impair the hydraulic continuity of rivers and other flow paths, and have the advantage of not allowing sediment to accumulate upstream, as they allow sediment to flow downstream during normal times and small to medium floods.

[0003] In such permeable sabo dams, a capture section is provided in the slit section with a water passage gap designed to prevent gravel or driftwood larger than a certain size from passing through, and various studies have been conducted on this topic. For example, Patent Document 1 describes a sediment capture member that uses beam members and spacers to flexibly accommodate the height of the waterway and is easy to install. Patent Document 2 describes a sabo dam with slit sections that uses a cover to cover the mounting section of a cross beam installed across the slit section to protect the mounting section of the cross beam from damage caused by debris carried down during floodwaters. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2007-056488 A [Patent Document 2] JP 2010-090698 A Summary of the Invention [Problem to be solved by the invention]

[0005] Permeable sabo dams, made of concrete or steel slits, generally capture the gravel in a debris flow but allow smaller gravel to slip through. Therefore, in areas with a large amount of small gravel such as granular granules, it has traditionally been necessary to use impermeable types when constructing sabo dams.

[0006] However, impermeable sabo dams block the flow of water and capture and accumulate sediment that would otherwise be washed downstream under normal circumstances or during small to medium-sized floods. This reduces the amount of sediment that can be captured during a debris flow. In addition, they cannot ensure the continuity of streams, and there are concerns that they may have an impact on the environment, such as preventing fish from migrating upstream.

[0007] One idea to solve this problem is to narrow the water gap in the capture section so that even permeable erosion control dams can capture small gravel, but it is difficult to construct the water gap solely from concrete or steel slits so that small gravel can be captured.It is also possible to use a separate component such as a net material to narrow the water gap, but there are concerns that the net material may be damaged by collisions with large gravel or driftwood, and that if the captured soil and sand are to be removed, it will have to be removed upstream of the erosion control dam (main embankment), making the work of removing the stones difficult.There are also concerns that even small to medium-sized floods can cause soil to be captured, and that the soil will quickly accumulate in the erosion control dam, requiring more frequent stone removal.

[0008] An object of the present invention is to provide a permeable sabo dam and capture unit that can solve the above-mentioned problems. [Means for solving the problem]

[0009] In order to achieve the above-mentioned object, the invention described in claim 1 is a sand-control dam installed in the middle of a flow path, comprising a dam body having a pair of side portions formed opposite each other at a predetermined distance and extending in a vertical direction defined by the height direction of the flow path, a bottom portion formed at the lower end of the pair of side portions and extending in a left-right direction defined by the width direction of the flow path, and a slit portion defined by the pair of side portions and the bottom portion, and a capture unit that is detachably attached to the dam body and limits the size of fluid passing through the slit portion to less than a predetermined size, and the capture unit has a frame portion that is detachable from the dam body, and a capture portion attached to the frame portion and prevents the passage of fluid of a predetermined size or larger.

[0010] With this configuration, by attaching the capture unit to the dam body of a sabo dam installed in the middle of the flow path of a river, etc., the size of the fluid passing through the slit section is restricted to less than a predetermined size. The capture unit can be removed from the dam body as necessary.

[0011] The invention described in claim 2 is the same as the invention described in claim 1, except that, in the configuration thereof, a pair of groove portions extending in the vertical direction are formed in each of the pair of side portions, and the frame portion includes a pair of vertical frame portions extending in the vertical direction, and each of the pair of vertical frame portions is inserted into a pair of grooves so that the capture unit is attached to the dam body.

[0012] With this configuration, the capture unit is attached to the dam body by inserting the vertical frame portion into the groove, and the capture unit can be removed from the dam body by pulling the vertical frame portion out of the groove.

[0013] The invention described in claim 3 is the same as the invention described in claim 2, in which the capture portion includes a plurality of cross beam members stretched across a pair of vertical frame portions at a predetermined interval in the vertical direction, and the cross beam members are detachably attached to each of the pair of vertical frame portions.

[0014] With this configuration, the cross beam members prevent the passage of objects larger than the interval between the cross beam members among the fluid objects passing through the capture unit. The cross beam members can be detached from the frame portion as required.

[0015] The invention described in claim 4 is the configuration of the invention described in claim 3, wherein each of the pair of vertical frame portions has a pair of cross beam fixing portions arranged to protrude opposite each other in the left-right direction at a predetermined interval in the up-down direction, each of the pair of cross beam fixing portions has an attachment hole, and the cross beam member is provided at each of its two end portions with a mounting fixture that is removably inserted into the attachment hole.

[0016] With this configuration, the mounting fixtures at both ends of the cross beam member are inserted into the mounting holes of the cross beam fixing portions of each of the pair of vertical frame portions, so that the cross beam member is stretched across the pair of vertical frame portions.

[0017] The invention described in claim 5 is such that, in the configuration of the invention described in claim 3 or claim 4, the cross beam member includes a metal chain and an elastic body that covers a portion of the metal chain in an elastically stretchable state.

[0018] With this configuration, when a load acts on the cross beam member in the stretching direction, the portion of the metal chain that is covered with the elastic body stretches elastically.

[0019] The invention as recited in claim 6 is the structure of the invention as recited in claim 5, further comprising a disconnecting means near the elastic body for disconnecting a portion of the metal chain so as to enable reconnection.

[0020] With this configuration, the cross beam members can be disconnected and reconnected midway as required.

[0021] The invention described in claim 7 is such that, in the configuration of the invention described in claim 1 or claim 2, the capture unit further includes a sheet-shaped capture aid arranged on the upstream side of the flow path in the frame portion, the frame portion further includes a locking holding portion that detachably holds the capture aid, and the size of the fluid through which the capture aid restricts passage is set smaller than the size of the fluid through which the capture portion restricts passage.

[0022] In this configuration, the size of the fluid that can pass through the capture unit is restricted to a smaller size by the capture assisting device. Also, the capture portion has a double structure of the cross beam member and the capture assisting device.

[0023] The invention described in claim 8 is the same as the invention described in claim 2, in which a step portion is formed in the bottom portion upstream of the pair of groove portions in the flow path, protruding upward from the bottom portion as a base.

[0024] With this configuration, at least a portion of the lower side of the frame portion is covered and hidden by the step portion when viewed from the upstream side.

[0025] The invention described in claim 9 is the same as the invention described in claim 8, in which the frame portion includes a lower frame portion connecting the lower ends of a pair of vertical frame portions, and the protruding height of the step portion from the bottom surface is set to be greater than the height dimension of the lower frame portion.

[0026] With this configuration, the lower frame portion is covered and hidden by the step portion when viewed from the upstream side.

[0027] The invention described in claim 10 comprises a frame portion constituting an outer frame, and a capture portion attached to the frame portion and preventing the passage of objects larger than a predetermined size, the frame portion including a pair of vertical frame portions arranged opposite each other, and the capture portion including a plurality of cross beam members detachably attached to each of the pair of vertical frame portions and stretched across the pair of vertical frame portions at a predetermined interval.

[0028] With this configuration, when used in an erosion control dam, the size of the fluid passing through is restricted to less than a predetermined size. Effect of the Invention

[0029] As explained above, the invention described in claim 1 can alleviate the restrictions on the size of objects that can pass through the slits by removing the capture unit when necessary. Also, in the unlikely event that the capture section is damaged by a collision with gravel or driftwood, only the capture unit needs to be replaced, and the dam body can be used as is, reducing the construction time and cost required for repairs.

[0030] In the invention as recited in claim 2, in addition to the effect of the invention as recited in claim 1, the capturing unit has an easy-to-handle shape, so that the capturing unit can be easily attached and detached from the groove portion.

[0031] The invention described in claim 3, in addition to the effect of the invention described in claim 2, can reduce repair costs by allowing only the affected cross beam member to be replaced when a part of the cross beam member is damaged, rather than replacing the entire capture unit.

[0032] The invention as recited in claim 4, in addition to the effects of the invention as recited in claim 3, makes it easier to attach and detach the cross beam member to the vertical frame portion, thereby simplifying the work of assembling the cross beam member to the frame portion at the construction site and replacing it at the construction site when necessary.

[0033] The invention described in claim 5 has the effect of the invention described in claim 3 or claim 4, in addition to the effect of the invention described in claim 5. When a load in the extension direction acts on the cross beam member, part of the load is consumed to elastically deform the elastic body, so that the metal chain is less likely to break even if a large load acts on it.

[0034] The invention described in claim 6 has the same effect as the invention described in claim 5, and can alleviate the restriction on the size of the object that can pass through the capture unit by separating some of the multiple cross beam members stretched across the left and right direction. The length of the cross beam member can be extended by inserting a separate member into the separated part of the metal chain.

[0035] The invention of claim 7 has the effect of removing small gravel from the flowing water in addition to the effect of the invention of claim 1 or 2. The capture aid is in a sheet form, so it is easy to handle. The impact on the capture unit can be supported by the cross beam member and the capture aid, improving durability.

[0036] The invention recited in claim 8 has the effect of the invention recited in claim 2, and in addition can mitigate direct collision of the lower part of the frame with fluids, thereby suppressing damage to the lower part of the frame.

[0037] The invention recited in claim 9, in addition to the effects of the invention recited in claim 8, can reliably mitigate direct collision of the lower frame portion with fluid, thereby reliably preventing damage to the lower frame portion.

[0038] The invention described in claim 10 unitizes the capture function part of the sabo dam, so that this part can be removed and replaced as needed, thereby reducing the time and cost required for repairs. [Brief description of the drawings]

[0039] [Figure 1] 1A and 1B show a dam body of a sabo dam according to one embodiment of the present invention, where FIG. 1A is a plan view and FIG. 1B is a front view seen from the downstream side. [Diagram 2] FIG. 2 is a cross-sectional view taken along line PP in FIG. [Diagram 3] FIG. 2 is an enlarged cross-sectional view taken along line QQ in FIG. 1(B). [Figure 4] 1 is a front view of a capture unit used in an erosion-control dam according to one embodiment of the present invention. FIG. [Diagram 5] FIG. 5 is a plan view of the capture unit shown in FIG. [Figure 6] FIG. 5 is an enlarged cross-sectional view taken along line RR in FIG. [Figure 7] FIG. 7 is an enlarged view of a portion of the lower end side of FIG. [Figure 8]5 is an enlarged cross-sectional view taken along line SS in FIG. 4, showing a main portion of the cross beam member. [Figure 9] FIG. 8 is a diagram showing a state in which the length of the cross beam member in FIG. 7 is extended. [Figure 10] 1A and 1B show a sabo dam according to one embodiment of the present invention, in which FIG. 1A is a plan view and FIG. 1B is a front view seen from the downstream side. [Figure 11] FIG. 11 is a cross-sectional view taken along line TT in FIG. 10(B). [Figure 12] FIG. 12 is an enlarged view of the capture unit shown in FIG. [Figure 13] 1 shows an example of an attachment structure for a frame portion of a capture aid device according to one embodiment of the present invention, in which (A) is a side view of a locking retaining portion provided on the upper frame portion, and (B) is a cross-sectional view taken along line UU in (A). [Figure 14] 1A shows a different example of the mounting structure of a capture aid device for a frame portion in one embodiment of the present invention, where (A) is a side view of a locking retaining portion provided on an upper frame portion, and (B) is a cross-sectional view taken along line VV of (A). [Figure 15] 13 shows yet another example of the mounting structure of a capture aid device for a frame portion according to one embodiment of the present invention, in which (A) is a side view of a locking retaining portion provided on an upper frame portion, and (B) is a cross-sectional view taken along line WW in (A). [Figure 16] 1A and 1B are views showing a state in which a cross beam member in a lower half of a sabo dam according to one embodiment of the present invention has been removed, where (A) is a front view and (B) is a cross-sectional view taken along line XX in (A). [Figure 17] 17 is an enlarged view of the storage state of the cross beam member shown in FIG. 16(B). FIG. [Figure 18] 17 is an enlarged cross-sectional view of the upper half of the capturing unit shown in FIG. 16(B). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0040] The present invention aims to suppress the outflow of small-grained sand and gravel that flows out during sweeping, and to improve workability by unitizing the capture function parts.

[0041] Recent landslide disasters are characterized by large-scale landslides such as debris flows that occur during heavy rainfall, and also by the fact that fine soil and sand continue to flow out over a long period of time due to rainfall when unstable soil and sand remain after the disaster, causing frequent flood damage in settlements and other areas. The present invention is a new sabo facility developed to deal with the above-mentioned continuous outflow of fine soil and to solve the problems of conventional sabo facilities. This new sabo dam is effective in preventing and reducing flood damage when a large amount of fine soil and sand remaining in a mountain stream after a heavy rainfall flows out into residential areas downstream due to subsequent rainfall. Moreover, the sabo dam of the present invention also improves economy and ease of construction by reducing the weight of the members used and making them precast.

[0042] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention, which has been devised to obtain the above-mentioned advantages, will now be described in detail with reference to the drawings showing the preferred embodiments thereof.

[0043] The main components of the sabo dam according to the present invention are the dam body and the capture unit. First, the dam body will be described. In the following description, the "up-down direction" refers to the direction defined by the height direction of the flow channel, and the "left-right direction" refers to the direction defined by the width direction of the flow channel.

[0044] Figures 1 to 3 show the dam body of a sand-control dam according to one embodiment of the present invention, where Fig. 1(A) is a plan view and Fig. 1(B) is a front view seen from the downstream side, Fig. 2 is a cross-sectional view taken along line PP in Fig. 1(B), and Fig. 3 is an enlarged cross-sectional view taken along line QQ in Fig. 1(B).

[0045] The dam body 1 of the sabo dam is constructed of concrete or the like and is installed across the width of a flow path of a river or the like. The dam body 1 comprises block sections 2a, 2b arranged to face each other at a predetermined interval on the left and right, a pair of side sections 3a, 3b formed at opposing positions of each of the block sections 2a, 2b and extending in the vertical direction, a bottom section 4 formed on the lower ends of the pair of side sections 3a, 3b and extending in the horizontal direction, and a slit section 5 defined by the pair of side sections 3a, 3b and the bottom section 4. Furthermore, a pair of groove sections 6a, 6b extending in the vertical direction is formed in each of the pair of side sections 3a, 3b.

[0046] 3, in this example, the inner surface of each groove 6a, 6b is reinforced with a reinforcing steel plate 61, and the surface is further covered with an elastic member. This is achieved by embedding an anchor bolt 65 with a sleeve 66 in the body of the side portion 3a on the three faces forming the groove 6a, and fixing an elastic protective member 62 onto the reinforcing steel plate 61 with a bolt 67 screwed into the sleeve 66. The elastic protective member 62 has a structure in which a steel plate 64 is embedded inside an elastic body 63 such as rubber, and for example, Rubber Steel (registered trademark: manufactured by Shibata Kogyo Co., Ltd.) is used.

[0047] Next, the capture unit will be described. Figures 4 to 9 show a capture unit used in a sabo dam according to one embodiment of the present invention, with Figure 4 being a front view, Figure 5 being a plan view, Figure 6 being an enlarged cross-sectional view taken along line RR in Figure 4, Figure 7 being an enlarged view of a portion of the lower end side of Figure 6, Figure 8 being an enlarged cross-sectional view taken along line SS in Figure 4 showing the main part of the cross beam member, and Figure 9 being a view showing the state in which the length of the cross beam member in Figure 7 has been extended.

[0048] Referring to Figure 4, the capture unit 10 is removably attached to the dam main body 1 for restricting the size of fluid passing through the slit portion 5 to less than a predetermined size, and includes as its main components a frame portion 11 that forms the outer frame, and a plurality of cross beam members 20 that form the capture portion 10a that prevents the passage of fluid above a predetermined size.

[0049] The frame portion 11 in this example is constructed, for example, from an H-shaped steel in a rectangular or square shape, and has a pair of left and right vertical frame portions 11a, 11b extending in the vertical direction in the installed state, an upper frame portion 11c connecting the upper ends of the left and right vertical frame portions 11a, 11b, and a lower frame portion 11d connecting the lower ends of the left and right vertical frame portions 11a, 11b.

[0050] 5, the upper frame portion 11c is provided on its upper surface with locking portions 13a and 13b for locking a wire rope or the like when hoisting or lowering the capturing unit 10. The locking portions 13a and 13b in this example are made of plate-like members having openings for passing the wire rope or the like therethrough.

[0051] 6, the vertical frame parts 11a and 11b are provided with a plurality of cross beam fixing parts 12a and 12b at a predetermined interval in the up-down direction on their respective opposing surfaces (sides facing inward of the frame part 11) for detachably attaching both ends of the cross beam member 20. In this example, the cross beam fixing parts 12a and 12b are plate-like members provided so as to protrude opposite each other in the left-right direction, and each of the cross beam fixing parts 12a and 12b has mounting holes 12p and 12q. The frame part 11 is also provided with locking and holding parts 31, 32, and 33 for mounting a sheet-like capture aid, which will be described later. In this example, the locking and holding parts 31, 32, and 33 are provided on the upper frame part 11c, the vertical frame part 11a, and the lower frame part 11d, respectively.

[0052] 7, a shock absorbing member 14 made of an elastic body is provided on the underside of the lower frame portion 11d. The shock absorbing member 14 in this example is made of a rubber body with a D-shaped cross section having a hollow portion inside, and is fixed using a bolt 16a that passes through the lower frame portion 11d and a nut 16b that is screwed onto the bolt 16a. By providing the shock absorbing member 14, the metal frame portion 11 is prevented from coming into direct contact with the bottom portion 4 of the concrete dam main body 1, thereby preventing damage to the bottom portion 4.

[0053] Referring to FIG. 8, the cross beam member 20 includes a metal chain 21 and an elastic body 22 such as rubber that covers a part of the metal chain 21 in an elastically stretchable state. Here, the elastically stretchable state means a state in which the metal chain has an extension margin between the links. With this configuration, when an external force acts on the cross beam member 20 in the extension direction, the part of the metal chain 21 covered with the elastic body 22 has an extension margin and can be extended. The extension operation at this time is accompanied by elastic deformation of the elastic body 22, so that the energy received from the external force is consumed for the elastic deformation. With this mechanism, the load-bearing performance of the cross beam member 20 of this example is improved, and it is less likely to break even when it is subjected to a large external force.

[0054] In addition, a detachable member such as a shackle is disposed on each chain link protruding from both ends of the elastic body 22. One of them functions as a mounting fixture 23 that enables the cross beam member 20 to be detached from the cross beam fixing parts 12a, 12b. The other functions as a disconnecting means 24 that separates the middle of the cross beam member 20 so that it can be reconnected.

[0055] The cross beam members 20 thus constructed can be stretched across the vertical frame portions 11a, 11b at predetermined intervals in the vertical direction by attaching both ends of the cross beam members 20 to the cross beam fixing portions 12a, 12b with mounting fixtures 23. These multiple cross beam members 20 function as capture portions 20a because they prevent the passage of objects larger than the interval between them.

[0056] The disconnection means 24 can separate the middle of the cross beam member 20 as necessary, alleviating restrictions on the size of objects that can pass through. Also, the length of the cross beam member 20 can be extended by inserting a separate member into the separation point of the metal chain 21. With reference to Fig. 9, for example, by inserting a turnbuckle 26 as a separate member into the separation point, the length of the cross beam member 20 can be extended in an expandable and contractible manner.

[0057] An erosion-control dam D according to the present invention is constructed by assembling a capture unit 10 to the above-mentioned dam body 1. Figure 10 shows an erosion-control dam according to one embodiment of the present invention, where (A) is a plan view, (B) is a front view seen from the downstream side, and Figure 11 is a cross-sectional view taken along line TT of (B) in Figure 10.

[0058] 10 and 11, the desired sabo dam D is constructed by attaching the capture units 10 by inserting the left and right vertical frame parts 11a, 11b into the grooves 6a, 6b formed in the left and right side parts 3a, 3b, respectively, of the dam main body 1. The dimensions of the grooves 6a, 6b and the vertical frame parts 11a, 11b are set so that appropriate gaps are created between them.

[0059] The sabo dam D constructed in this way maintains the logical continuity of the flow path through the gaps between the multiple cross beam members 20, and allows non-harmful sediment to flow downstream during normal times or small to medium floods. When the water level in the flow path rises or a debris flow occurs, the cross beam members 20 of the capture unit 10 hold back objects of a certain size, such as driftwood and rocks, preventing them from flowing downstream and causing damage to houses, facilities, roads, etc.

[0060] In this example, the elastic protective material 62 arranged in the grooves 6a and 6b and the buffer member 14 arranged in the lower frame portion 11d prevent the frame portion 11 of the capture unit 10 from directly contacting the dam body 1. This reduces the risk of the dam body 1 being damaged by a collision with the frame portion 11.

[0061] In this example, a step portion 7 is formed on the bottom surface 4 of the dam body 1 on the upstream side of the grooves 6a and 6b, protruding upward from the bottom surface 4. The step portion 7 is set to have a protruding height h from the bottom surface 4 equal to or greater than the height dimension of the lower frame portion 11d. The vertical frame portions 11a and 11b are also set to be entirely housed in the grooves 6a and 6b. With this configuration, the vertical frame portions 11a and 11b and the lower frame portion 11d are covered by the grooves 6a and 6b and the step portion 7 when viewed from the upstream side of the flow path, so that collision of objects carried by the water current with them can be mitigated. This reliably prevents damage to the vertical frame portions 11a and 11b and the lower frame portion 11d, thereby improving the durability of the capture unit 10.

[0062] Furthermore, by providing the step 7 and hiding the lower frame portion 11d, there is an advantage that the lower frame portion 11d is less likely to be subjected to external forces such as water pressure and earth pressure. This eliminates the need to increase the pressure resistance performance required of the lower frame portion 11d, making it possible to reduce the weight of the lower frame portion 11d.

[0063] By forming the step portion 7, it is considered that gravel with a large particle size is less likely to remain near the step portion 7, and gravel that accumulates around the grooves 6a and 6b becomes small enough to be easily removed by hand. This makes it easier to reinstall the capture unit 10 after removing it from the grooves 6a and 6b. In this example, the height of the step portion 7 from the bottom surface 4 is set to about 320 mm in consideration of the height of the buffer member 14 when the width of the H-shaped steel used in the frame portion 11 is 250 mm, for example, and is designed so that the upper surface of the lower frame portion 11d and the surface of the step portion 7 are almost flush with each other.

[0064] The sabo dam D having the above-mentioned configuration can be easily constructed by simply suspending the separately manufactured capture units 10 by a crane or the like and inserting them into the grooves 6a, 6b of the dam body 1, thereby reducing the amount of on-site construction work and shortening the construction period. In particular, the capture units 10 can be preassembled, for example, at a factory or other site, and transported to the construction site by a truck or other transportation means, reducing the number of on-site work steps, ensuring the safety of workers, and improving construction accuracy. Furthermore, if the capture units 10 are damaged by being struck by gravel or driftwood, only the capture units 10 need to be replaced, and the dam body 1 can be used as is, resulting in excellent workability and economy during repair work.

[0065] Furthermore, when removing the capture unit 10 after it has been hit by gravel or driftwood, for example, if the cross beam member 20 is removed from the downstream side to allow an operator to enter the frame portion 11, the soil that has filled the gap between the frame portion 11 and the groove portions 6a, 6b can be removed with a water jet or the like, making it easier to hoist the capture unit 10 with a crane, etc.

[0066] Furthermore, a separate permeable sabo dam made of concrete or steel slits may be installed upstream of the sabo dam of this example. In this way, large gravel and driftwood are captured first by the permeable sabo dam, and only the sediment that has slipped through the upstream permeable sabo dam is captured by the capture unit of this example, making it easier to remove the sediment captured by the capture unit of this example.

[0067] The capturing unit 10 of this embodiment may be equipped with a sheet-like capturing aid. Fig. 12 is an enlarged view of the capturing unit shown in Fig. 11, Fig. 13 shows an example of a structure for mounting the capturing aid to the frame according to an embodiment of the present invention, where (A) is a side view of a locking and holding part provided on the upper frame, and (B) is a cross-sectional view taken along line UU in (A), Fig. 14 shows a different example of the same mounting structure, where (A) is a side view of a locking and holding part provided on the upper frame, and (B) is a cross-sectional view taken along line VV in (A), and Fig. 15 shows yet another example of the same mounting structure, where (A) is a side view of a locking and holding part provided on the upper frame, and (B) is a cross-sectional view taken along line WW in (A).

[0068] 12, the capture unit 10 of this embodiment may be provided with a sheet-like water-permeable capture aid 40 attached to the upstream side of the flow path in the frame portion 11. The capture aid 40 limits the size of the fluid that can pass through to be smaller than the size of the fluid that the cross beam member 20 allows to pass through. For example, a synthetic resin or metal net may be used for this, and a polyethylene net is preferable in consideration of strength, cost, ease of handling, etc. When a net is used, the mesh size is preferably 20 to 50 mm, but a smaller or larger mesh size may be used depending on the installation situation.

[0069] Meanwhile, the frame portion 11 is provided with a locking and holding portion for detachably holding the capture aid 40. In this example, when the capture aid 40 is made in a net shape, the mesh of the net is utilized for attachment, so that the upper frame portion 11c, the vertical frame portions 11a and 11b, and the lower frame portion 11d are provided with locking and holding portions 31, 32, and 33 using shackles or bolts and nuts. These locking and holding portions 31 to 33 allow the capture aid 40 to be attached so as to cover almost the entire upstream surface of the multiple cross beam members 20.

[0070] Next, a specific configuration of the locking and holding parts 31 to 33 will be described with reference to Figures 13 to 15. Note that, although Figures 13 to 15 show the configuration of the locking and holding part 31 provided on the upper frame part 11c, the same configuration can also be adopted for the locking and holding parts 32 and 33 of the vertical frame parts 11a, 11b and the lower frame part 11d.

[0071] The locking and holding part 31 shown in Fig. 13 is composed of a holding plate 31a provided on the upper frame part 11c and a shackle 31b attached to an opening formed in the holding plate 31a. The shackle 31b is attached to the holding plate 31a with the mesh near the upper end 40a of the capture aid 40 engaged with the shackle 31b. This causes the upper end 40a of the capture aid 40 to be locked to the upper frame part 11c.

[0072] 14 is composed of a retaining plate 31a provided on the upper frame portion 11c, and a bolt 31c, a nut 31d, and a pressing plate 31e that are attached by utilizing an opening formed in the retaining plate 31a. The pressing plate 31e is placed near the upper end 40a of the capture aid 40, and the bolt 31c that penetrates the retaining plate 31a is inserted into the opening of the retaining plate 31a and the nut 31d is screwed and tightened, whereby the upper end 40a of the capture aid 40 is locked to the upper frame portion 11c.

[0073] The locking and holding part 31 shown in Fig. 15 is composed of a holding plate 31a provided on the upper frame part 11c, a shackle 31b attached to an opening formed in the holding plate 31a, a bolt 31c, a nut 31d, and a pressing plate 31f. The vicinity of the upper end 40a of the capture aid 40 is folded back onto the shackle 31b, and the shackle 31b engaged with the mesh in this state is attached to the holding plate 31a. Furthermore, the vicinity of the folded back upper end 40a of the capture aid 40 is clamped and tightened by the bolt 31c and the nut 31d via the pressing plate 31f, so that the upper end 40a of the capture aid 40 is locked to the upper frame part 11c.

[0074] As described above, the capture unit 10 equipped with the capture aid 40 can limit the size of the flowing matter that can pass through it by the capture aid 40, so that small-grained sand and gravel can be removed from the flowing matter. By appropriately setting the hole diameter of the capture aid 40, fine-grained sediment can also be removed. Furthermore, by arranging the capture aid 40 on the upstream side, it is possible to prevent driftwood and the like from getting entangled in the cross beam member 20. By making the capture aid 40 in a sheet form, it is possible to obtain the advantage of easy handling. Furthermore, since the capture aid 40 is detachable, it also has the advantage of facilitating the removal of gravel accumulated on the upstream side as necessary. Furthermore, since the flow path can be opened, fish can swim upstream, and since sediment can be passed through and supplied to the downstream area during normal flooding, it can also be used to counter coastal erosion, which has become a problem in recent years.

[0075] However, as mentioned above, when the capture aid 40 is attached to the capture unit 10, there is a possibility that it may hinder the passage of soil and sand that may be washed away under normal circumstances. In addition, there is a risk that the passage may become clogged with fallen leaves, and water that should flow downstream may accumulate. Therefore, during normal times or non-flooding when the possibility of flooding is low, a part of the cross beam member 20 of the capture unit 10 and a part of the capture aid 40 may be removed to ensure a flow path.

[0076] Figure 16 shows the state in which the lower cross beam member has been removed from a sand-control dam according to one embodiment of the present invention, where (A) is a front view and (B) is a cross-sectional view along line XX of (A). Figure 17 is an enlarged view of the storage state of the cross beam member shown in Figure 16(B), and Figure 18 is an enlarged cross-sectional view of the upper half of the capture unit shown in Figure 16(B).

[0077] 16, during periods when the possibility of flooding in the river or the like where the sabo dam D is installed is low or during non-flooding periods, the lower cross beam member 20 may be removed from the frame portion 11 and the lower half of the capture aid 40 may be folded back upward. This allows water to pass freely through the lower half of the capture portion 20a of the capture unit 10, easing restrictions on the size of objects that can be passed through.

[0078] Incidentally, referring to FIG. 17, a holding plate 50 may be fixed to the dam body 1 with anchor bolts 51 or the like, and the removed cross beam member 20 may be locked thereto for storage.

[0079] Also, referring to Figure 18, a shackle 35 for temporary fastening may be further provided on the upper frame portion 11c, so that when the lower half of the assisting capture device 40 is folded upward, the lower end of the assisting capture device 40 is engaged with this shackle 35 to maintain the folded state.

[0080] In the above embodiment, the capture unit is inserted into a groove in the dam body and attached, but the capture unit may also be removably fixed to the dam body using an anchor bolt or the like embedded in the dam body.

[0081] In addition, in the above embodiment, the dam body has a step portion, but the step portion may be omitted.

[0082] Furthermore, depending on the construction environment, a sleeve may be formed on the upper surface of the block portion of the dam body.

[0083] Furthermore, the outer shape of the capture unit may be other than rectangular or square. For example, the upper frame may be formed in an arch shape. Alternatively, the lower frame may be formed in an isosceles trapezoid shape with a narrower width.

[0084] Furthermore, the cross beam members may be made of rod-shaped or plate-shaped steel material other than metal chains.

[0085] Furthermore, the cross beam fixing portion of the vertical frame portion may be a ring-shaped member in addition to a plate-shaped member.

[0086] Furthermore, the capture aid is not limited to a net body, and any material that is water permeable and has the function of restricting the particle size of objects that can pass through can be used.

[0087] Furthermore, in the embodiment of FIG. 16, the cross beam member and the lower half of the capture aid are removed to ensure a flow path, but the entire capture unit may be removed, or only the capture aid may be removed.

[0088] Furthermore, the frame portion of the capture unit may be constructed from angle steel, channel steel, joist steel (I-beam), square steel pipes, etc., in addition to H-shaped steel.

[0089] Furthermore, in the above embodiment, shackles are used as the attachments and disconnection means for the cross beam members, and as the locking and retaining parts for the vertical frame parts, but other members or jigs may be used for some or all of these. The disconnection means may be omitted.

[0090] Furthermore, in the above-described embodiment, the height of the step portion of the dam body may be lower than the height of the lower frame portion, and the step portion may be partially omitted.

[0091] Furthermore, in the above embodiment, the capture aid may be omitted.

[0092] Furthermore, the flow path in which the sabo dam is installed may be a flow path that is in a dry state during normal times or in the dry season, and in which water flows only during heavy rainfall or in the rainy season. [Explanation of symbols]

[0093] D…Sabo dam 1…Dam body 3a, 3b...side part 4…Bottom part 5…Slit section 6a, 6b...Groove 7…Step 10…Capture unit 11...Frame section 11a, 11b...Vertical frame section 11d…Lower frame section 12a, 12b...Horizontal beam fixing part 14...Cushioning material 20...Beam member 21...Metal chain 22...Elastic body 23...Mounting fixture 24...Disconnection means 31, 32, 33...locking holding part 40... Retrieval aid In addition, the same symbols in each drawing indicate the same or corresponding parts.

Claims

1. A sabo dam installed midway through a river channel, a dam body including a pair of side surfaces formed to face each other at a predetermined interval and extending in a vertical direction defined by a height direction of the flow channel, a bottom surface portion formed on lower ends of the pair of side surfaces and extending in a left-right direction defined by a width direction of the flow channel, and a slit portion defined by the pair of side surfaces and the bottom surface portion; a capture unit that is detachably attached to the dam body and limits the size of the fluid passing through the slit portion to less than a predetermined size, The capture unit of this erosion-control dam comprises a frame portion that is detachable from the dam body, and a capture portion that is attached to the frame portion and prevents the passage of fluids of a predetermined size or larger.

2. A pair of grooves extending in the up-down direction are formed on each of the pair of side surfaces, The frame portion includes a pair of vertical frame portions extending in the up-down direction, 2. The sabo dam according to claim 1, wherein the pair of vertical frame portions are inserted into the pair of groove portions, respectively, to mount the capture unit to the dam body.

3. The capture portion includes a plurality of cross beam members stretched across the pair of vertical frame portions at predetermined intervals in the up-down direction, The cross beam member is detachably attached to each of the pair of vertical frame portions.

3. The sabo dam according to claim 2.

4. Each of the pair of vertical frame portions includes a pair of cross beam fixing portions provided to protrude opposite to each other in the left-right direction at a predetermined interval in the up-down direction, Each of the pair of cross beam fixing portions has an attachment hole, 4. The sabo dam according to claim 3, wherein the cross beam member is provided at each of both ends with a mounting fixture which is detachably inserted into the mounting hole.

5. 5. A sabo dam according to claim 3, wherein the cross beam member includes a metal chain and an elastic body covering a part of the metal chain in an elastically stretchable state.

6. 6. A sabo dam according to claim 5, further comprising a disconnecting means for disconnecting said metal chain midway in the vicinity of said elastic body so as to enable reconnection.

7. The capturing unit further includes a sheet-like capturing aid disposed on the upstream side of the flow path in the frame portion, The frame portion further includes a locking holding portion that detachably holds the capture aid, 3. The sabo dam according to claim 1, wherein the size of the fluid that is restricted by the trapping aid is set smaller than the size of the fluid that is restricted by the trapping portion.

8. 3. The sabo dam according to claim 2, wherein a step portion is formed in the bottom portion upstream of the pair of groove portions in the flow path, the step portion protruding upward from the bottom portion as a base.

9. The frame portion includes a lower frame portion connecting lower ends of the pair of vertical frame portions, 9. The sabo dam according to claim 8, wherein a protruding height of said step portion from said bottom surface portion is set to be larger than a height dimension of said lower frame portion.

10. The device includes a frame portion that constitutes an outer frame, and a capture portion that is attached to the frame portion and that prevents the passage of an object having a predetermined size or larger, The frame portion includes a pair of vertical frame portions disposed opposite each other, The capture portion includes a plurality of cross beam members detachably attached to each of the pair of vertical frame portions and stretched across the pair of vertical frame portions at a predetermined interval. Capture unit for erosion control dams.

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