Capture structure and weir

Abstract

To prevent a catching body from being damaged by rocks and drift woods climbing over the catching body.SOLUTION: A catching body (1) provided in a dam (100), making flowing water flowing from an upstream side of a river pass, and catching objects included in the flowing water comprises: an upstream side unit (2) which is provided at an upstream side of the river and catches an object; a downstream side unit (3) which is provided at a downstream side of the river and whose center portion is formed to be bent so as to protrude toward the upstream side unit; and a connection portion (4) which connects the upstream side unit and the downstream side unit. Each end of the downstream side unit is attached to non-overflow portions (110) constructed at both sides in a direction crossing the river in the catching body.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a catching body and a dam provided with the catching body.

Background Art

[0002] As a countermeasure for debris flow in a river, a dam (debris flow prevention dam) provided with a catching body for catching rocks, driftwood, etc. flowing from upstream is known. The dam has a pair of non-overflow portions protruding from both banks of the river. An opening for passing water is provided between the non-overflow portions. The catching body is provided at the opening, and while allowing earth and sand and water with a small diameter to pass through, it catches rocks, driftwood, etc. with a large diameter. The catching body has an upstream unit facing the upstream side in the flow direction of the river and a downstream unit facing the downstream side, and both units are inclined and extend so as to approach each other as they go upward, and are connected to each other in the vicinity of their upper end portions. The catching body is provided across the width direction of the opening, and is attached to a concrete foundation at its lower end (see, for example, Patent Document 1). When debris flow collides with the catching body, a force that tries to knock down the catching body to the downstream side acts. The catching body is configured not to fall by transmitting this force from the lower end to the concrete foundation.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Incidentally, in large rivers or rivers where large debris flows are predicted, high dams are often constructed with a height of 15m or more from the bottom of the concrete foundation to the top. In the case of high dams, the trapping body also needs to be constructed to a high height, but since the upstream and downstream units slope and extend upward so that they move closer to each other, the higher the trapping body becomes, the greater the distance between the top and bottom ends of the trapping body along the direction of river flow. As a result, rocks and driftwood that overflowed the trapping body would fall towards the lower end of the downstream unit, damaging the downstream unit and preventing the force acting on the trapping body from being transmitted to the concrete foundation.

[0005] Therefore, the present invention has been made in view of the above problems, and aims to provide a technology that prevents the trap from being damaged by rocks or driftwood that have passed over it. [Means for solving the problem]

[0006] To solve the above problems, the present invention provides a trapping body that allows flowing water from the upper reaches of a river to pass through and captures objects contained in the flowing water, comprising: an upstream unit provided on the upstream side of the river for capturing the objects; a downstream unit provided on the downstream side of the river, formed by bending its central portion so as to protrude toward the upstream unit; and a connecting portion connecting the upstream unit and the downstream unit, wherein each end of the downstream unit is attached to non-overflow portions constructed on both sides of the trapping body in the direction crossing the river.

[0007] Furthermore, it is preferable that the downstream unit is provided along the direction of crossing the river and comprises a plurality of beam sections formed by bending so that the central part protrudes toward the upstream unit.

[0008] Furthermore, it is preferable that the downstream unit includes a plurality of column sections that connect the plurality of beam sections.

[0009] Furthermore, it is preferable that each end of the upstream unit is attached to a non-overflow section.

[0010] Furthermore, it is preferable that the upstream unit includes a plurality of beam sections provided along the direction of crossing the river.

[0011] Furthermore, it is preferable that the upstream unit includes a plurality of column sections that connect the plurality of beam sections.

[0012] To solve the above problems, the present invention provides a trapping body that allows flowing water from the upper reaches of a river to pass through and captures objects contained in the flowing water, comprising: an upstream unit provided on the upstream side of the river, which captures the objects and is formed by bending at least its central portion to protrude toward the upper reaches of the river; a downstream unit provided on the downstream side of the river, which is formed by bending at least its central portion to protrude toward the upstream unit; and a connecting portion that connects the upstream unit and the downstream unit, wherein each end of the upstream unit and the downstream unit is attached to non-overflow portions constructed on both sides of the trapping body in the direction that crosses the river.

[0013] Furthermore, it is preferable that the downstream unit is provided along the direction of crossing the river and comprises a plurality of beam sections formed by bending so that the central part protrudes toward the upstream unit.

[0014] Furthermore, it is preferable that the downstream unit includes a plurality of column sections that connect the plurality of beam sections.

[0015] Furthermore, it is preferable that the upstream unit is provided along the direction of crossing the river and comprises a plurality of beam sections formed by bending so that the central part protrudes toward the upstream unit.

[0016] Further, it is preferable that the upstream unit includes a plurality of beam portions having a first straight portion provided along a direction crossing the river and formed to extend linearly, and a second straight portion having one end connected to an end of the first straight portion and the other end attached to the non-overflow portion downstream of the first straight portion.

[0017] Further, it is preferable that the upstream unit includes a plurality of column portions connecting the plurality of beam portions to each other.

[0018] In order to solve the above problems, the present invention is a weir provided with a capture body according to any one of the above, comprising a pair of non-overflow portions protruding from both banks of a river, an opening provided between the pair of non-overflow portions, and the capture body provided in the opening for passing flowing water flowing from the upstream of the river and capturing an object contained in the flowing water.

Effects of the Invention

[0019] According to the present invention, the capture body is not damaged by rocks or driftwood that have overcome the capture body.

Brief Description of the Drawings

[0020] [Figure 1] It is a perspective view of a weir provided with a capture body. [Figure 2] It is an enlarged view of the capture body in FIG. 1. [Figure 3] It is a front view of the capture body as seen from the upstream side. [Figure 4] It is a plan view of the capture body. [Figure 5] It is a diagram for explaining the connection structure between the column portion and the base portion of the capture body. [Figure 6] It is a plan view showing a modified example of the capture body. [Figure 7] It is a plan view showing a modified example of the capture body. [Figure 8] It is a plan view showing a modified example of the capture body. [Figure 9] It is a front view showing a modified example of the capture body. [Figure 10]This is a front view showing a modified version of the capture device. [Figure 11] This is a front view showing a modified version of the capture device. [Figure 12] This is a front view showing a modified version of the capture device. [Figure 13] Figure 12 is a plan view of the trapping body. [Figure 14] This is a perspective view of a dam showing a modified form of the trapping structure. [Figure 15] This is a magnified view of the capture body in Figure 14. [Figure 16] Figure 14 is a front view of the trapping body as seen from the downstream side. [Figure 17] Figure 16 is a plan view of the capture body. [Figure 18] This is a plan view showing a modified version of the capture body. [Modes for carrying out the invention]

[0021] Preferred embodiments of the present invention will be described with reference to the drawings.

[0022] A trapping structure allows water flowing from the upper reaches of a river to pass through while trapping objects such as rocks, sediment, and driftwood contained in the water. It is installed on weirs. For example, trapping structures are applied to high dams, as shown in Figure 1. Here, a "high dam" refers to a dam where the height H from the riverbed (bottom) where the dam's foundation is installed to the tip of the trapping structure is 15m or more. High dams are mainly installed on large rivers or rivers where large debris flows are predicted.

[0023] As shown in Figures 1 and 2, the weir 100 comprises a pair of non-overflow sections (wing sections) 110, a foundation section 120, and a trapping body 1. The non-overflow sections 110 are formed of concrete. Each pair of non-overflow sections 110 extends from both banks of the river across the river towards the center. An opening 111 is formed between the pair of non-overflow sections 110 at a predetermined interval. The foundation 120 is formed of concrete at the bottom of the opening 111. The foundation 120 is formed on the riverbed. River water, sand, gravel, etc. that have flowed from upstream pass through the opening 111.

[0024] As shown in Figures 1 to 4, the trapping body 1 is attached to the non-overflow section 110 located on both sides in the direction of river flow (both sides in the direction crossing the river) at the opening 111 of the sediment control dam 100. Capture device 1 allows flowing water from the upper reaches of the river to pass through while also capturing objects such as rocks and driftwood.

[0025] The capture unit 1 comprises an upstream unit 2, a downstream unit 3, and a connecting part 4. Upstream unit 2 is located on the upstream side of the river and captures objects such as rocks and driftwood contained in the debris flow that has flowed from the upstream side of the weir 100. In other words, upstream unit 2 is a unit that is directly subjected to the impact of the debris flow. The upstream unit 2 is installed in a straight line along the direction that crosses the river when the weir 100 is viewed from above. The upstream unit 2 comprises multiple beam sections (horizontal members) 21 and multiple column sections (vertical members) 22. Multiple beam sections 21 are provided along the direction crossing the river and are arranged in a line along the height direction of the weir 100. As shown in Figure 3, the gap G1 formed between adjacent beam sections 21 (the distance between the lowest part of the upper beam section 21 and the highest part of the lower beam section 21) is preferably approximately equal to the maximum gravel diameter D95. Furthermore, the distance G2 between the lowest part of the beam section 21 located at the very bottom and the upper surface of the foundation section 120 is preferably, for example, approximately 1.5 times the maximum gravel diameter D95, or approximately equal to the water depth of the debris flow. The beam section 21 is composed of, for example, a plurality of cylindrical steel pipes 21a, and each steel pipe 21a is connected to one another via flange sections 21b provided at both ends in the axial direction. Although the ends of each steel pipe 21a may be connected by welding without providing flange sections 21b, connection using flange sections 21b is preferable considering repair and replacement work after debris flow impact. Each beam section 21 is attached to a non-overflow section 110 at both of its longitudinal ends, which are opposite each other. Specifically, as shown in Figure 4, a cylindrical sheath pipe 112 is pre-embedded in the non-overflow section 110, and the steel pipe 21a located at the end of the beam section 21 is fitted into this sheath pipe 112.

[0026] Multiple column sections 22 are provided along the height direction of the dam 100 and connect adjacent beam sections 21 to each other. Multiple column sections 22 are arranged in a line along the height direction of the dam 100. As shown in Figure 3, the gap G3 formed between adjacent column sections 22 (the distance between the rightmost part of the column section 22 located on the left and the leftmost part of the column section 22 located on the right) is preferably about 5m, for example, taking into account the stress state acting on the column section 21. Furthermore, the distance G4 between the leftmost (or rightmost) part of the column section 22 located on the far left (or right) and the side surface of the non-overflow section 110 facing the column section 22 is preferably about 5 m, for example, taking into consideration the stress state acting on the column section 21. The column section 22 is composed of, for example, a plurality of cylindrical steel pipes 22a, with one axial end of each steel pipe 22a welded to the steel pipe 21a of the beam section 21, and the other axial end being connected to each other via a flange section 22b provided at that other end. In other words, the column section 22 is composed of two steel pipes 22a, but it may be composed of three or more steel pipes 22a connected together depending on the size of the dam 100. Note that each steel pipe 22a may be connected at the ends by welding without providing a flange section 22b, but considering repair and replacement work after debris flow impact, connection using a flange section 22b is preferable. A column section 22c is connected to the beam section 21, which is located at the lowest point in the height direction of the dam 100, and to the foundation section 120. The lower end of the column section 22c is embedded in the foundation section 120, and as a result, the lower end of the column section 22 is erected in the foundation section 120.

[0027] The downstream unit 3 is located on the downstream side of the river, and the impact load of the debris flow acting on the upstream unit 2 is transmitted via the connecting part 4 to support the trapping body 1. The downstream unit 3 is positioned along the direction that crosses the river when the weir 100 is viewed from above, and its central portion in the direction of extension is curved to protrude toward the upstream unit 2. In other words, the downstream unit 3 employs a curved arch structure and supports the impact load of the debris flow transmitted from the upstream unit 2 via the connecting portion 4 with compressive force. The downstream unit 3 comprises a plurality of beam sections 31 and a plurality of column sections 32. Multiple beam sections 31 are provided along the direction crossing the river and are arranged at approximately equal intervals along the height direction of the weir 100. In Figure 3, the downstream unit 3 is positioned to overlap the upstream unit 2 and is not shown, but it is preferable that the gap G1 formed between adjacent beam sections 31 (the gap between the lowest part of the upper beam section 31 and the highest part of the lower beam section 31) be approximately equal to, for example, the maximum gravel diameter D95. Furthermore, the distance G2 between the lowest part of the lowermost beam section 31 and the upper surface of the foundation section 120 is preferably, for example, approximately 1.5 times the maximum gravel diameter D95, or approximately equal to the water depth of the debris flow. Note that the spacing of the beam sections 31 in the downstream unit 3 is the same as the spacing of the beam sections 21 in the upstream unit 2, and therefore the same reference numerals are used. The beam section 31 is positioned opposite the beam section 21 of the upstream unit 2 in the direction of river flow.

[0028] The beam section 31 is composed of, for example, a plurality of cylindrical steel pipes 31a. Since the steel pipes 31a are required to withstand the impact load of a debris flow, it is preferable to use steel pipes with a larger diameter and higher strength than the steel pipes 21a that make up the beam section 21 of the upstream unit 2. Each steel pipe 31a is connected to each other at both ends in the axial direction via a connector 33. Specifically, the connector 33 is a box made of steel plate filled with a binder such as concrete or mortar and solidified. The ends of the steel pipes 31a are inserted into the box, and the binder is filled in to integrate the box, the binder, and the steel pipes 31a, thereby connecting the steel pipes 31a to each other. The advantage of using the connector 33 to connect the steel pipes 31a is that the connection angle of the steel pipes 31a can be freely adjusted. That is, the angle formed by the steel pipes 31a can be adjusted by adjusting the position of the steel pipes 31a relative to the connector 33. Alternatively, each steel pipe 31a may be connected by cutting the ends at a predetermined angle and welding them together without using the connector 33. Furthermore, the steel pipes 31a may be straight pipes extending along the axial direction, or curved pipes along the axial direction, and the appropriate steel pipe can be selected depending on the curvature of the beam section 31.

[0029] Each beam section 31 is formed by bending so that its central portion in the longitudinal direction (axial direction) protrudes toward the upstream unit 2. That is, the steel pipe 31a located near the longitudinal center of the beam section 31 is closer to the beam section 21 of the upstream unit 2, and as it approaches the end of the beam section 31, it moves further away from the beam section 21 of the upstream unit 2. By connecting the steel pipes 31a with connectors 33 in this arrangement, the beam section 31 can be formed into a curved arch shape. Each beam section 31 is attached to opposing non-overflow sections 110 at both of its longitudinal ends. Specifically, as shown in Figure 4, flange sections 31b are provided at the ends of the steel pipes 31a located at both ends of each beam section 31, and the beam section 31 is fixed to the non-overflow section 110 by installing anchor members 113 to the non-overflow section 110 via the flange sections 31b.

[0030] Multiple column sections 32 are provided along the height direction of the dam 100 and connect adjacent beam sections 31 to each other. Multiple column sections 32 are arranged in a line along the height direction of the dam 100. The gap G3 formed between adjacent column sections 32 (the distance between the rightmost part of the column section 32 located on the left and the leftmost part of the column section 32 located on the right) is preferably about 5m, taking into consideration the stress state acting on the column section 32. Furthermore, the distance G4 between the leftmost (or rightmost) part of the leftmost (or rightmost) column section 32 and the side surface of the non-overflow section 110 facing the column section 32 is preferably about 5m, taking into consideration the stress state acting on the column section 32. Note that the spacing of the column sections 32 in the downstream unit 3 is the same as the spacing of the column sections 22 in the upstream unit 2, and therefore the same reference numerals are used. The column section 32 is composed of, for example, a plurality of cylindrical steel pipes 32a, and the axial ends of each steel pipe 32a are connected to connectors 33 of the adjacent beam section 31. The column section 32 may be formed not only from a single steel pipe 32a, but also by connecting a plurality of steel pipes 32a. A column section 32c is connected to a connector 33 of the beam section 31, which is located at the lowest point in the height direction of the dam 100, and the column section 32c connects the beam section 31 to the foundation section 120. The lower end of the column section 32c is embedded in the foundation section 120, and as a result, the lower end of the column section 32 is erected in the foundation section 120.

[0031] Here, we will describe the connection structure between column sections 22c and 32c and the foundation section 120. As shown in Figure 5, column sections 22c and 32c are erected on the foundation section 120. The column sections 22c and 32c are erected on the foundation section 120 via a base 9 that is pre-installed on the foundation section 120 and is adjustable in both the vertical and horizontal directions. Specifically, the base 9 is formed in the same way as the flange sections 22f and 32f of the column sections 22c and 32c, and multiple anchor bolts 91 are inserted through it at intervals. One end of each anchor bolt 91 is embedded in the foundation section 120, and the other end is inserted through a hole formed in the base 9. The base 9 is sandwiched between two nuts 92 that are screwed onto the anchor bolts 91, and the position of the base 9 in the vertical direction (the direction in which the column sections 22c and 32c extend) can be adjusted by adjusting the position of the nuts 92. Furthermore, the holes formed in the base 9 are sized to allow for clearance relative to the cross-section of the anchor bolts 91, allowing the lateral position of the base 9 (the direction in which the beam sections 21 and 31 extend) to be adjusted. After the position adjustment, the flange sections 22f and 32f of the column sections 22c and 32c are placed on the base 9, and the anchor bolts 91 are inserted through the holes in the flange sections 22f and 32f of the column sections 22c and 32c. The positions of the column sections 22c and 32c are fixed by sandwiching the base 9 and the flange sections 22f and 32f with nuts 92. The lower ends of the column sections 22c and 32c, including the flange sections 22f and 32f, are embedded together with the base 9 by concrete pouring after connection to the base 9, thereby firmly fixing them to the foundation 120. Furthermore, the column sections 22c and 32c that connect the beam sections 21 and 31 located at the lowest point in the height direction of the dam 100 to the foundation section 120 may be formed integrally with a part of the lowest beam section 21 and 31, or they may be formed integrally with a part of the beam section 21 and 31 and the column sections 22a and 32a located above it.

[0032] The connecting section 4 connects the upstream unit 2 and the downstream unit 3. The connecting section 4 is provided along the direction of river flow and connects the beam section 21 of the upstream unit 2 and the beam section 31 of the downstream unit 3, which are opposite each other. That is, the connecting sections 4, like the beam sections 21 and 31, are arranged at approximately equal intervals along the height direction of the weir 100. Therefore, the spacing between adjacent connecting sections 4 is set to be smaller than the diameter of the rocks that should be captured when a debris flow occurs. The connecting section 4 is composed of, for example, a cylindrical steel pipe 4a. One end of the steel pipe 4a is connected to the steel pipe 21a in the beam section 21 of the upstream unit 2 by welding or the like, and the other end is connected to the connector 33 in the beam section 31 of the downstream unit 3. Furthermore, each steel pipe 4a may be connected not only to the connector 33, but also by welding to the steel pipe 31a in the beam section 31 of the downstream unit 3.

[0033] With the trapping body 1 and dam 100 described above, when a debris flow occurs and collides with the dam 100, large-diameter rocks and driftwood contained in the debris flow collide with the upstream unit 2 of the trapping body 1 and are trapped. On the other hand, small-diameter sediment and water contained in the debris flow flow out to the downstream side of the dam 100 through the gap between the upstream unit 2 and the downstream unit 3 (between the beam sections 21, 31 and the column sections 22, 32). The collision of the debris flow places a large impact load on the upstream unit 2. While the beams 21 and columns 22 that make up the upstream unit 2 can mitigate this impact by deforming, they cannot withstand the entire load. At this time, a portion of the impact load acting on the upstream unit 2 is transmitted to the downstream unit 3 via the connecting section 4. When the impact load is transmitted to the downstream unit 3, the arch-shaped beam section 31 supports the impact load of the debris flow transmitted from the upstream unit 2 via the connecting section 4 as a compressive force acting on the beam section 31, with the anchor member 113 providing support. Since the anchor member 113 is provided in the non-overflow section 110, the impact load can be received even in the non-overflow section 110. Therefore, since the impact load of the debris flow can be received not only by the upstream unit 2 but also by the downstream unit 3, a very strong trapping body 1 and weir 100 can be constructed. Furthermore, since both ends of the beam section 31 are attached to the non-overflow section 110, even if rocks and driftwood contained in the debris flow over the upper ends of the upstream unit 2 and the downstream unit 3 and fall below the trapping body 1, they will not directly hit the connection between the trapping body 1 and the foundation section 120 as in the conventional method, thus preventing the trapping body 1 from tipping over due to damage. Furthermore, the beam section 31 of the downstream unit 3 is bent into an arch shape so that its central part protrudes toward the upstream unit 2, allowing it to support the impact load of the debris flow with compressive force alone, thus making the beam section 31 less susceptible to damage.

[0034] In the downstream unit 3, the beam sections 31 are arranged in a line along the height direction of the dam 100, and the column sections 32 are arranged in a line along the height direction of the dam 100 between adjacent beam sections 31. Therefore, when the dam 100 is viewed from above, the beam sections 31 located below the downstream unit 3 do not protrude downstream from the beam sections 31 located above. As a result, even if rocks and driftwood contained in the debris flow over the upper ends of the upstream unit 2 and the downstream unit 3 and fall below the trapping body 1, the rocks and driftwood will not hit the beam sections 31 of the downstream unit 3, thus preventing damage to the beam sections 31 from direct impact by rocks and other debris. Furthermore, since the downstream unit 3 does not necessarily need to be connected to the foundation 120, there is no need to construct a large foundation 120 to prevent the capture body 1 from tipping over. Furthermore, since each beam section 21 of the upstream unit 2 is connected by a column section 22, and each beam section 31 of the downstream unit 3 is connected by a column section 32, the rigidity of both the upstream unit 2 and the downstream unit 3 can be increased. Furthermore, since the connecting section 4 is positioned along the direction of river flow, the impact load from the upstream unit 2 can be smoothly transmitted to the downstream unit 3.

[0035] <Variation> Next, we will describe a modified version of the capture body. In the above-described capture body 1, connectors 33 were used to connect the steel pipes 31a that constitute the beam section 31 of the downstream unit 3, to connect the beam sections 31 to each other, and to connect the upstream unit 2 and the downstream unit 3. However, as shown in Figure 6, for example, connectors 33 may be used instead of using connectors 33, and connector pipes 5 prepared in advance at a factory or the like may be used. As shown in Figure 6, the connecting pipe 5 in the capture body 1A is connected to the steel pipe 31a as part of the steel pipe 31a that constitutes the beam section 31. The connecting pipe 5 is provided at a position where it connects to the column section 32 and the connecting section 4 in the beam section 31. The connecting pipe 5 has a beam pipe section 5a that forms part of the beam section 31, a column pipe section 5b that forms part of the column section 32, and a connecting pipe section 5c that forms part of the connecting section 4, and these are connected by welding and formed as a single unit. A flange is provided at each end of the beam pipe section 5a, the column pipe section 5b, and the connecting pipe section 5c, and through these flanges, the connecting pipe 5 is connected to the steel pipe 31a of the beam section 31, the steel pipe 32a of the column section 32, and the steel pipe 4a of the connecting section 4, respectively. This configuration allows the downstream unit 3 to be formed without using the connector 33. In this case, the connecting pipe 5 has its beam pipe section 5a, column pipe section 5b, and connecting pipe section 5c connected to each other in advance at a factory or the like to match the curvature of the downstream unit 3. Therefore, unlike with the connector 33, the attachment angle of the steel pipe 31a of the beam section 31 to the connecting pipe 5 cannot be adjusted at the construction site of the dam 100, but the number of work steps at the construction site can be reduced.

[0036] Furthermore, as shown in Figure 7, the steel pipes may be connected without using the connectors 33. Here, in Figure 6, the connecting pipe 5 is used only in the part of the beam section 31 where the column section 32 and the connecting section 4 are connected, whereas in Figure 7, the beam section 31 is mostly constructed of connecting pipes 6. As shown in Figure 7, the connecting pipe 6 in the capture body 1B is provided as part of the steel pipe 31a that constitutes the beam section 31. The connecting pipe 6 has a beam pipe section 6a that forms part of the beam section 31, a column pipe section 6b that forms part of the column section 32, and a connecting pipe section 6c that forms part of the connecting section 4, which are connected by welding and formed as a single unit. The beam pipe section 6a also constitutes most of the beam section 31, and is therefore formed to be longer than the beam pipe section 5a in Figure 6. In Figure 7, all of the beam section 31 except for the steel pipes 31a at both ends is made up of connecting pipes 6. Each end of the beam pipe section 6a, column pipe section 6b, and connecting pipe section 6c is provided with a flange, and the connecting pipe 6 is connected via these flanges to the steel pipe 31a of the beam section 31, the steel pipe 32a of the column section 32, and the steel pipe 4a of the connecting section 4, respectively. This configuration allows the downstream unit 3 to be formed without using the connector 33. In this case, the connecting pipe 6 has its beam pipe section 6a, column pipe section 6b, and connecting pipe section 6c connected to each other in advance at a factory or the like to match the curvature of the downstream unit 3. Therefore, unlike with the connector 33, the angle at which the steel pipe 31a of the beam section 31 is attached to the connecting pipe 6 cannot be adjusted at the construction site of the dam 100, but the number of work steps at the construction site can be reduced.

[0037] Furthermore, as shown in Figure 8, the connecting section that links the upstream unit 2 and the downstream unit 3 may be provided in a truss shape when viewed from above. As shown in Figure 8, the capture body 1C has the same configuration as the capture body 1 shown in Figure 4 for the upstream unit 2 and the downstream unit 3, but in addition to the connecting part 4, a connecting part 7 is provided, and the connecting part 7 connects the upstream unit 2 and the downstream unit 3. The connecting section 7 is provided between adjacent connecting sections 4 arranged along the direction of river flow, and is provided along a direction intersecting the extending direction of the connecting sections 4. The connecting section 7 is composed of, for example, a cylindrical steel pipe 7a. One end of the steel pipe 7a is connected by welding or the like to the connection point between the beam section 21 of the upstream unit 2 and the connecting section 4, and the other end is connected to a connector 33 on the beam section 31 of the downstream unit 3. Note that each connecting section 7 may not only be connected at one end to the connection point between the beam section 21 of the upstream unit 2 and the connecting section 4, but may also be connected to a steel pipe 21a between adjacent connecting sections 4. Furthermore, each connecting section 7 may not only be connected at the other end to a connector 33, but may also be connected by welding to a steel pipe 31a on the beam section 31 of the downstream unit 3. Furthermore, the connecting section 7 is not limited to being a single section spanning between adjacent connecting sections 4; two connecting sections 7 may be arranged so as to intersect each other, or two or more connecting sections 7 may be spanned between the upstream unit and the downstream unit 3.

[0038] Alternatively, an upstream unit 2A as shown in Figure 9 may be used. In the upstream unit 2A, the spacing between each beam section 21 and the column section 22 is smaller than that of the upstream unit 2 described above. Specifically, in the upstream unit 2A, the spacing G5 of the gap formed between adjacent beam sections 21 (the distance between the lowest part of the upper beam section 21 and the highest part of the lower beam section 21) may be approximately equal to, for example, the maximum gravel diameter D95. Furthermore, the distance G6 between the lowest part of the beam section 21 located at the very bottom and the upper surface of the foundation section 120 may be, for example, approximately 1.5 times the maximum gravel diameter D95, or approximately equal to the water depth of the debris flow. The gap G7 formed between adjacent column sections 22 (the distance between the rightmost part of the column section 22 located on the left and the leftmost part of the column section 22 located on the right) may be approximately equal to, for example, the maximum gravel diameter D95. Furthermore, the distance G8 between the leftmost (or rightmost) part of the column section 22 located on the leftmost (or rightmost) side and the side surface of the non-overflow section 110 facing the column section 22 may be, for example, about the maximum gravel diameter D95 or less.

[0039] Alternatively, an upstream unit 2B as shown in Figure 10 may be used. The upstream unit 2B has a second column section 23 connected between the lowest beam section 21 and the foundation section 120, separate from the column section 22. Specifically, in the upstream unit 2B, the gap G9 formed between adjacent beam sections 21 (the distance between the lowest part of the upper beam section 21 and the highest part of the lower beam section 21) may be approximately equal to, for example, the maximum gravel diameter D95. Furthermore, the distance G10 between the lowest part of the beam section 21 located at the very bottom and the upper surface of the foundation section 120 may be, for example, approximately 1.5 times the maximum gravel diameter D95, or approximately equal to the water depth of the debris flow. The gap G11 formed between adjacent column sections 22 (the distance between the rightmost part of the column section 22 located on the left and the leftmost part of the column section 22 located on the right) is preferably about 5m, for example, taking into consideration the stress state acting on the column section 22. Furthermore, the distance G12 between the leftmost (or rightmost) part of the column section 22 located on the far left (or right) and the side surface of the non-overflow section 110 facing the column section 22 is preferably about 5m, for example, taking into consideration the stress state acting on the column section 22. Here, the lowest beam section 21 has a second column section 23 connected to it, in addition to the column section 22 mentioned above. One end of the second column section 23 is connected to the lowest beam section 21, and the other end is connected to the foundation section 120. The spacing G13 between adjacent second column sections 23, and between column section 22 and the second column section 23 (the spacing between the rightmost part of the column section 22(23) located on the left and the leftmost part of the column section 22(23) located on the right) may be approximately equal to, for example, the maximum gravel diameter D95. Furthermore, the distance G14 between the leftmost (or rightmost) part of the second column section 23 located on the leftmost (or rightmost) side and the side surface of the non-overflow section 110 facing the second column section 23 may be, for example, about the maximum gravel diameter D95 or less than or equal to the maximum gravel diameter D95.

[0040] Alternatively, an upstream unit 2C as shown in Figure 11 may be used. The upstream unit 2C has different spacings between adjacent beam sections 21 in the upper and lower height directions. Specifically, in the upstream unit 2C, the spacing G15 (the distance between the lowest part of the upper beam section 21 and the highest part of the lower beam section 21) formed between adjacent beam sections 21 in the upper section (for example, beam sections 21 located above half the height of the upstream unit 2C) may be approximately equal to the maximum gravel diameter D80 (≒D95 / 1.66), and the spacing G16 (the distance between the lowest part of the upper beam section 21 and the highest part of the lower beam section 21) formed between adjacent beam sections 21 in the lower section (for example, beam sections 21 located below half the height of the upstream unit 2C) may be approximately equal to the maximum gravel diameter D95. Furthermore, the distance G17 between the lowest part of the beam section 21 and the upper surface of the foundation section 120 may be, for example, approximately 1.5 times the maximum gravel diameter D95, or approximately equal to the water depth of the debris flow. The gap G18 formed between adjacent column sections 22 (the distance between the rightmost part of the column section 22 located on the left and the leftmost part of the column section 22 located on the right) is preferably about 5m, for example, taking into consideration the stress state acting on the column section 22. Furthermore, the distance G19 between the leftmost (or rightmost) part of the column section 22 located on the far left (or right) and the side surface of the non-overflow section 110 facing the column section 22 is preferably about 5m, for example, taking into consideration the stress state acting on the column section 22. In the example shown in Figure 11, the downstream unit 3 is not visible as it overlaps with the upstream unit 2, but it is preferable that the downstream unit 3 also has the same beam spacing and column spacing as the upstream unit 2C. Furthermore, the position where the spacing between the beam sections 21 is changed is not limited to half the height of the upstream unit 2C, but can be freely changed according to the expected properties of the debris flow. In addition, the spacing between the beam sections 21 is not limited to two different spacings, but may be configured to have three or more different spacings.

[0041] Alternatively, a capture body 1D as shown in Figures 12 and 13 may be used. The trapping body 1D comprises an upstream unit 2D and a downstream unit 3D. Here, the difference between trapping body 1D and trapping body 1 shown in Figures 3 and 4 lies in the mounting structure of the upstream unit 2D and the downstream unit 3D to the non-overflow section 110. In the following, the differences between trapping body 1D and trapping body 1 will be explained, and components common to trapping body 1 will be given the same reference numerals and their explanations will be omitted. Each beam section 21 is attached to opposing non-overflow sections 110 at both of its longitudinal ends. Specifically, as shown in Figures 12 and 13, a support frame 40 is embedded in the non-overflow section 110 so that a portion of it is exposed from the non-overflow section 110, and a steel pipe 21a located at the end of the beam section 21 is connected to this support frame 40.

[0042] The support structure 40 is embedded in the non-overflow section 110 such that a portion of it is exposed from the non-overflow section 110. The support structure 40 is connected to the upstream unit 2D and the downstream unit 3D. The support structure 40 is used to firmly fix the upstream unit 2D and the downstream unit 3D to the non-overflow section 110. The support structure 40 is provided for each non-overflow section 110, at a position opposite the end of the beam section 21 of the upstream unit 2D and at a position opposite the end of the beam section 31 of the downstream unit 3D. Multiple support structures 40 are connected along the height direction of the non-overflow section 110, and are provided at positions that allow them to connect to the beam sections 21 and 31 of the upstream unit 2D and the downstream unit 3D. The frame 40 comprises a plurality of vertical sections 41 and a plurality of horizontal sections 42.

[0043] Multiple vertical sections 41 are provided along the height direction of the dam 100. Each vertical section 41 is composed of, for example, multiple cylindrical steel pipes, the axial ends of which are connected to one another via flanges. The lower ends of the vertical sections 41, which are directly provided on the foundation of the non-overflow section 110, are embedded in the foundation, and as a result, the lower ends of the vertical sections 41 are erected on the foundation.

[0044] Multiple horizontal sections 42 are provided so as to intersect the vertical sections 41 midway along the axial direction of the vertical sections 41, and are arranged at approximately equal intervals along the height direction of the dam 100. Each horizontal section 42 is made up of, for example, multiple cylindrical steel pipes, and each steel pipe is connected to the beam sections 21 and 31 of the upstream unit 2D and the downstream unit 3D via a flange provided at one end of its axial direction. Each horizontal section 42 is provided so as to penetrate the vertical section 41, and is joined to the vertical section 41 at their intersection. Each horizontal section 42 is provided such that one end in the longitudinal direction is exposed from the non-overflow section 110 to the opening 111, and is arranged so that it can be connected to the beam sections 21 and 31 at this end. The support frame 40 is embedded in the non-overflow section 110, except for the connection points with the beam sections 21 and 31 in the horizontal section 42. By embedding the support frame 40 in the non-overflow section 110, the beam sections 21 and 31 are fixed to the non-overflow section 110, and the upstream unit 2D and the downstream unit 3D are firmly fixed to the side wall of the non-overflow section 110. The support structure 40 extends in the height direction of the non-overflow section 110 by connecting multiple ends of each other's vertical sections 41.

[0045] Alternatively, a capture body 1E as shown in Figures 14 to 17 may be used. The capture unit 1E comprises an upstream unit 2E, a downstream unit 3E, and a connecting unit 4E. The upstream unit 2E is located on the upstream side of the river and captures objects such as rocks and driftwood contained in the debris flow that has flowed from the upstream side of the weir 100. In other words, the upstream unit 2E is a unit that is directly subjected to the impact of the debris flow. The upstream unit 2E is positioned along the direction that crosses the river when the weir 100 is viewed from above, and its central portion in the direction of extension is curved to protrude upstream of the river. In other words, the upstream unit 2E employs a curved arch structure, resulting in a structure that reduces the combined stress on the upstream unit 2E with respect to thermal stress (internal stresses generated in the structure due to temperature changes (for example, stresses due to the expansion and contraction of each component due to changes in ambient temperature)). The upstream unit 2E comprises a plurality of column sections 21 and a plurality of beam sections 22. Each column section 21 is composed of multiple vertical members 21a connected together, and each beam section 22 is composed of multiple horizontal members 22a connected together.

[0046] Multiple vertical members 21a are provided along the height direction of the dam 100, and adjacent horizontal members 22a in the height direction are connected. Multiple vertical members 21a are arranged in a line along the width direction of the dam 100. It is preferable that the spacing between adjacent vertical members 21a be smaller than the diameter of the rocks to be captured when a debris flow occurs. Furthermore, the spacing between adjacent vertical members 21a may be the same throughout the width direction of the capture body 1E, or the spacing may be narrowed only near the center of the width direction of the capture body 1E, and can be freely changed according to the expected scale of the debris flow. The vertical members 21a are formed, for example, from steel pipes that are cylindrical in shape and have a straight axis along their longitudinal direction. In the trapping body 1E, multiple vertical members 21a are connected in the longitudinal direction, and each vertical member 21a is connected to one another via flanges provided at its longitudinal end. For example, as shown in Figure 14, the trapping body 1E has three vertical members 21a. Although each vertical member 21a may be connected by welding at its ends without flanges, connection using flanges is preferable considering replacement work after debris flow impact.

[0047] Each vertical member 21a is provided with multiple connecting parts 23a, 24a between its longitudinal ends that connect to the horizontal members 22a. Specifically, the vertical member 21a, which is positioned at the lowest point in the capture body 1E and whose lower end is embedded in the foundation 120 of the opening 111, has two first connecting parts 23a that connect one adjacent horizontal member 22a and two second connecting parts 24a that connect the other adjacent horizontal member 22a between their longitudinal ends. The pair of first connecting parts 23a and second connecting parts 24a are provided at the same height. The first connecting parts 23a and second connecting parts 24a are formed, for example, from a cylindrical steel pipe with a straight axis along its longitudinal direction. The first connecting parts 23a and second connecting parts 24a extend in a direction perpendicular to the longitudinal direction of the vertical member 21a, with one end joined to the vertical member 21a by welding or the like, and the other end having a flange portion that connects to the horizontal member 22a. Furthermore, one end of the first connecting portion 23a and the second connecting portion 24a may be connected to the vertical member 21a via a flange portion.

[0048] In the trapping body 1E, the vertical member 21a, positioned second from the bottom, is provided with three first connecting parts 23a that connect adjacent horizontal members 22a between their longitudinal ends, and three second connecting parts 24a that connect adjacent horizontal members 22a. Pairs of first connecting parts 23a and second connecting parts 24a are provided at the same height. The first connecting parts 23a and second connecting parts 24a are formed, for example, from a cylindrical steel pipe with a straight axis along its longitudinal direction. The first connecting parts 23a and second connecting parts 24a extend in a direction perpendicular to the longitudinal direction of the vertical member 21a, with one end joined to the vertical member 21a by welding or the like, and the other end having a flange portion that connects to the horizontal member 22a. One end of the first connecting parts 23a and second connecting parts 24a may also be connected to the vertical member 21a via the flange portion.

[0049] The vertical member 21a, positioned at the uppermost position in the capture body 1E, comprises five first connecting portions 23a connecting one adjacent horizontal member 22a between its longitudinal ends, and five second connecting portions 24a connecting the other adjacent horizontal member 22a. Pairs of first connecting portions 23a and second connecting portions 24a are provided at the same height. The first connecting portions 23a and second connecting portions 24a are formed, for example, from a cylindrical steel pipe with a straight axis along its longitudinal direction. The first connecting portions 23a and second connecting portions 24a extend in a direction perpendicular to the longitudinal direction of the vertical member 21a, with one end joined to the vertical member 21a by welding or the like, and the other end provided with a flange portion for connecting to the horizontal member 22a. One end of the first connecting portions 23a and second connecting portions 24a may also be connected to the vertical member 21a via the flange portion.

[0050] Multiple horizontal members 22a are provided along the direction crossing the river and are arranged in a line along the height direction of the weir 100. Preferably, the spacing between adjacent horizontal members 22a is smaller than the diameter of the rocks to be captured when a debris flow occurs. Furthermore, the spacing between adjacent horizontal members 22a may be the same throughout from the top to the bottom of the capture body 1E, or the spacing may be narrowed only above the capture body 1E, and can be freely changed according to the expected scale of the debris flow. The horizontal members 22a are provided in a position opposite to the horizontal members 32a of the downstream unit 3E in the direction of river flow. The horizontal members 22a are formed, for example, from a cylindrical steel pipe with a straight axis along its longitudinal direction. Each horizontal member 22a is connected to the first connecting portion 23a and the second connecting portion 24a of the vertical member 21a via flanges provided at its longitudinal ends. While the ends of each horizontal member 22a may be connected by welding without flanges, connection using flanges is preferable considering replacement work after debris flow impact. Of the horizontal members 22a, the horizontal member 22a positioned furthest out in the width direction of the river has one end in the longitudinal direction attached to the side wall of the opposite non-overflow section 110. Specifically, as shown in Figure 14, the end of the horizontal member 22a is connected to a support frame 40, and by embedding this support frame 40 in the non-overflow section 110, each horizontal member 22a is fixed to the non-overflow section 110. Note that the configuration of the support frame 40 is the same as the configuration shown in Figures 12 and 13 described above, so its explanation is omitted. Furthermore, the attachment structure of the horizontal member 22a to the non-overflow section 110 is not limited to the use of a support frame 40; it may also be a structure in which the member is inserted into a sheath pipe pre-installed in the non-overflow section 110.

[0051] The downstream unit 3E is located downstream of the river when viewed from the upstream unit 2E, and the impact load of the debris flow acting on the upstream unit 2E is transmitted via the connecting unit 4E to support the trapping body 1E. The downstream unit 3E is positioned along the direction that crosses the river when the weir 100 is viewed from above, and its central portion in the direction of extension is curved to protrude toward the upstream unit 2E. In other words, the downstream unit 3E employs a curved arch structure and is a structural member that supports the impact load of the debris flow transmitted from the upstream unit 2E via the connecting unit 4E with compressive force. The downstream unit 3E comprises a plurality of column sections 31 and a plurality of beam sections 32. Each column section 31 is composed of a plurality of vertical members 31a connected together, and each beam section 32 is composed of a plurality of horizontal members 32a connected together.

[0052] Multiple vertical members 31a are provided along the height direction of the dam 100, and adjacent horizontal members 32a in the height direction are connected. Multiple vertical members 31a are arranged in a line along the width direction of the dam 100. It is preferable that the spacing between adjacent vertical members 31a be smaller than the diameter of the rocks to be captured when a debris flow occurs. Furthermore, the spacing between adjacent vertical members 31a may be the same throughout the width direction of the capture body 1E, or the spacing may be narrowed only near the center of the width direction of the capture body 1E, and can be freely changed according to the expected scale of the debris flow. The vertical members 31a are formed, for example, from steel pipes that are cylindrical in shape and have a straight axis along their longitudinal direction. In the trapping body 1E, multiple vertical members 31a are connected in the longitudinal direction, and each vertical member 31a is connected to one another via flanges provided at its longitudinal end. For example, as shown in Figure 14, the trapping body 1E has three vertical members 31a. Although each vertical member 31a may be connected by welding at its ends without flanges, connection using flanges is preferable considering replacement work after debris flow impact.

[0053] Each vertical member 31a is provided with multiple connecting parts 33a, 34a between its longitudinal ends that connect to the horizontal member 32a. Specifically, the vertical member 31a, which is positioned at the lowest point in the capture body 1E and whose lower end is embedded in the foundation 120 of the opening 111, has two first connecting parts 33a that connect one adjacent horizontal member 32a and two second connecting parts 34a that connect the other adjacent horizontal member 32a between their longitudinal ends. The pair of first connecting parts 33a and second connecting parts 34a are provided at the same height. The first connecting parts 33a and second connecting parts 34a are formed, for example, from a cylindrical steel pipe with a straight axis along its longitudinal direction. The first connecting parts 33a and second connecting parts 34a extend in a direction perpendicular to the longitudinal direction of the vertical member 31a, with one end joined to the vertical member 31a by welding or the like, and the other end having a flange portion that connects to the horizontal member 32a. Furthermore, one end of the first connecting portion 33a and the second connecting portion 34a may be connected to the vertical member 31a via a flange portion.

[0054] In the trapping body 1E, the vertical member 31a, positioned second from the bottom, is provided with three first connecting parts 33a that connect adjacent horizontal members 32a between their longitudinal ends, and three second connecting parts 34a that connect adjacent horizontal members 32a. Pairs of first connecting parts 33a and second connecting parts 34a are provided at the same height. The first connecting parts 33a and second connecting parts 34a are formed, for example, from a cylindrical steel pipe with a straight axis along its longitudinal direction. The first connecting parts 33a and second connecting parts 34a extend in a direction perpendicular to the longitudinal direction of the vertical member 31a, with one end joined to the vertical member 31a by welding or the like, and the other end having a flange portion that connects to the horizontal member 32a. One end of the first connecting parts 33a and second connecting parts 34a may also be connected to the vertical member 31a via the flange portion.

[0055] The vertical member 31a, positioned at the uppermost position in the capture body 1E, comprises five first connecting portions 33a that connect adjacent horizontal members 32a between their longitudinal ends, and five second connecting portions 34a that connect adjacent horizontal members 32a. Pairs of first connecting portions 33a and second connecting portions 34a are provided at the same height. The first connecting portions 33a and second connecting portions 34a are formed, for example, from a cylindrical steel pipe with a straight axis along its longitudinal direction. The first connecting portions 33a and second connecting portions 34a extend in a direction perpendicular to the longitudinal direction of the vertical member 31a, with one end joined to the vertical member 31a by welding or the like, and the other end having a flange portion that connects to the horizontal member 32a. One end of the first connecting portions 33a and second connecting portions 34a may also be connected to the vertical member 31a via the flange portion.

[0056] Multiple horizontal members 32a are provided along the direction crossing the river and are arranged in a line along the height direction of the weir 100. Preferably, the spacing between adjacent horizontal members 32a is smaller than the diameter of the rocks to be captured when a debris flow occurs. Furthermore, the spacing between adjacent horizontal members 32a may be the same throughout from the top to the bottom of the capture body 1E, or the spacing may be narrowed only above the capture body 1E, and can be freely changed according to the expected scale of the debris flow. The horizontal members 32a are provided in a position opposite to the horizontal members 22a of the upstream unit 2E in the direction of river flow. The horizontal members 32a are formed, for example, from a cylindrical steel pipe with a straight axis along its longitudinal direction. Each horizontal member 32a is connected to the first connecting portion 33a and the second connecting portion 34a of the vertical member 31a via a flange portion provided at its longitudinal end. Since each horizontal member 32a is required to withstand the impact load of a debris flow, it is preferable to use a steel pipe with a larger diameter and higher strength than the steel pipe constituting the horizontal member 22a of the upstream unit 2E. Although each horizontal member 32a may be connected by welding at its ends without providing a flange portion, connection using a flange portion is preferable considering replacement work after impact with a debris flow. Of the horizontal members 32a, the horizontal member 32a positioned furthest out in the width direction of the river has one end in the longitudinal direction attached to the side wall of the opposite non-overflow section 110. Specifically, as shown in Figure 14, the end of the horizontal member 32a is connected to a support frame 40, and by embedding this support frame 40 in the non-overflow section 110, each horizontal member 32a is fixed to the non-overflow section 110.

[0057] Each beam section 22 and each beam section 32 is bent into an arch shape so that its central part in its extending direction (the axial direction of the horizontal members 22a and 32a) protrudes most towards the upstream side of the river. When viewed from above, each beam section 22 and each beam section 32 facing each other in the direction of river flow are arranged to be approximately equally spaced from one end to the other. That is, the beam sections 22 and 32 facing each other along the direction of river flow are connected by multiple connecting units 4E of the same length. Each column section 21 connects each beam section 22 to each other, and each column section 31 connects each beam section 32 to each other.

[0058] The connecting unit 4E connects the upstream unit 2E and the downstream unit 3E. The connecting unit 4E is installed along the direction of river flow and connects the vertical members 21a of the upstream unit 2E and the vertical members 31a of the downstream unit 3E, which are opposite each other. In other words, the connecting unit 4E is arranged in a line along the height direction of the weir 100, similar to the horizontal members 22a and 32a. Therefore, the spacing between adjacent connecting units 4E is set to be smaller than the diameter of the rocks to be captured when a debris flow occurs. Furthermore, the spacing between adjacent connecting units 4E can be the same throughout, from the top to the bottom of the capture body 1E, similar to the horizontal members 22a and 32a, or the spacing can be narrowed only above the capture body 1E, etc., and can be freely changed according to the expected scale of the debris flow. The connecting unit 4E is formed, for example, from a cylindrical steel pipe with a straight axis along its longitudinal direction. One end of the connecting unit 4E is connected to the vertical member 21a of the upstream unit 2E by welding or the like, and the other end is connected to the vertical member 31a of the downstream unit 3E by welding or the like. Furthermore, at the uppermost ends of the upstream unit 2E and the downstream unit 3E, in addition to connecting the vertical members 21a and 31a, the horizontal members 22a and 32a may also be connected by a connecting unit 4E. Also, the connecting unit 4E is not limited to connections made by welding or the like, but may also be connected using a flange portion.

[0059] As described above, since the upstream unit 2E is fixed to the non-overflow section 110, the impact load from the debris flow can be released to the non-overflow section 110. When considering thermal stress in this case, the combined stress becomes large when the upstream unit 2E is formed in a straight line. The thermal stress increases as the height and width of the dam increase, as in the case of a high dam. However, as shown in Figures 14 to 17, the capture body 1E on the upstream side is formed by bending, so even when both ends are fixed to the non-overflow section 110 via the support frame 40, the combined stress with respect to thermal stress can be reduced. This makes it possible to increase the strength of the weir 100 while reducing the combined stress with respect to thermal stress, and also makes it possible to reduce the diameter of the steel pipe of the upstream side unit 2E. Furthermore, by arranging the upstream unit 2E and the downstream unit 3E at equal intervals across the entire width of the capture body 1E, it is possible to standardize the column sections 21, 31 and beam sections 22, 32 of the upstream unit 2E and the downstream unit 3E, as well as standardize the connecting unit 4E. Accordingly, it is also possible to easily install a cover member that connects the upper end of the upstream unit 2E and the upper end of the downstream unit 3E to prevent rocks and driftwood from falling between the upstream unit 2E and the downstream unit 3E.

[0060] Alternatively, a capture body 1F as shown in Figure 18 may be used. Capture unit 1F is a modified version of capture unit 1E shown in Figures 14 to 17, with the configuration of the upstream unit 2E changed to that of the upstream unit 2F. Below, we will explain the upstream unit 2F, which is the difference between capture unit 1F and capture unit 1E. The capture unit 1F comprises an upstream unit 2F, a downstream unit 3F, and a connecting unit 4F. As shown in Figure 18, the upstream unit 2F is installed along the direction that crosses the river when the weir 100 is viewed from above, and its central part in the direction of extension is bent so that it protrudes toward the upstream of the river. In other words, the upstream unit 2F employs a structure in which it is bent near both ends, resulting in a structure that reduces the combined stress of the upstream unit 2F in relation to temperature stress.

[0061] The upstream unit 2F is comprised of multiple column sections (vertical members) (not shown) and multiple beam sections (horizontal members) 22. Multiple beam sections 22 are provided along the direction crossing the river and are arranged in a line along the height direction of the weir 100. The beam section 22 comprises a first straight section 221 and a second straight section 222. The first straight section 221 is formed to extend linearly along the width direction of the capture body 2F. The first straight section 221 is located in the central part of the upstream unit 2F. The second straight section 222 is formed in a straight line so as to extend in a direction intersecting the extending direction of the first straight section 221. One end of the second straight section 222 is connected to the end of the first straight section 221, and the other end is attached to the non-overflow section 110 downstream of the first straight section 221. The first straight section 221 and the second straight section 222 are composed of, for example, a plurality of cylindrical steel pipes, and each steel pipe is connected to the others via flanges provided at both ends in the axial direction. Although the ends of each steel pipe may be connected by welding without flanges, connection using flanges is preferable considering repair and replacement work after debris flow impact. The other end of the second straight section 222 is attached to the opposite non-overflow section 110. Specifically, as shown in Figure 18, a support frame 40 is embedded in the non-overflow section 110 so that a portion of it is exposed from the non-overflow section 110, and the second straight section 222 is connected to this support frame 40. The second straight section 222 is positioned so as to be approximately equal in distance from the horizontal member 32a connected to the frame 40 in the downstream unit 3F. The configuration of the support frame 40 is the same as that shown in Figures 12 and 13 above, so its explanation is omitted. Furthermore, the attachment structure of the second straight section 222 to the non-overflow section 110 is not limited to the case where the support frame 40 is used; it may also be a structure in which the second straight section 222 is inserted into a sheath pipe that is pre-installed in the non-overflow section 110.

[0062] The downstream unit 3F has the same configuration as the downstream unit 3E in the capture body 1E. The connecting unit 4F connects the upstream unit 2F and the downstream unit 3F. The connecting unit 4F is installed along the direction of river flow and connects the vertical members of the upstream unit 2F and the vertical members of the downstream unit 3F, which are opposite each other. As shown in Figure 18, in the upstream unit 2F, the first straight section 221 extends along the width direction of the capture body 1F, so the distance between the first straight section 221 and the downstream unit 3F widens as it approaches the widthwise end of the capture body 1F. Therefore, the connecting unit 4F, which is closer to the widthwise end of the capture body 1F, is formed to be longer. The connecting unit 4F may be constructed by joining a single steel pipe to each vertical member by welding or other means, or by connecting multiple steel pipes via flange sections.

[0063] As described above, according to the trapping body 1F shown in Figure 18, the upstream unit 2F is formed by bending to have a first straight section 221 and a second straight section 222. Therefore, even when both ends are fixed to the non-overflow section 110 via the support frame 40, the combined stress due to thermal stress can be reduced. This makes it possible to increase the strength of the weir 100 while reducing the combined stress due to thermal stress, and also makes it possible to reduce the diameter of the steel pipe of the upstream unit 2F.

[0064] <Other> While preferred embodiments of the present invention have been described, the present invention is not limited to the embodiments described above, but includes all aspects included in the concept and claims of the present invention. Furthermore, each component may be selectively combined as appropriate to achieve at least some of the above-described problems and effects. For example, the shape, material, arrangement, size, etc., of each component in the above embodiments may be appropriately changed depending on the specific use of the present invention. Additionally, a screen may be provided in the area enclosed by the upper end of the upstream unit 2 and the upper end of the downstream unit 3 of the trapping body 1. This screen is a measure to prevent rocks and driftwood from falling between the upstream unit 2 and the downstream unit 3. Furthermore, although the example of trapping body 1 being installed on a weir 100 called a high dam was described, it may also be installed on a weir that is not a high dam. Furthermore, if the trapping body 1 having the above configuration is adopted, the trapping body 1 is connected to the non-overflow section 110, so the construction of the foundation section 120 may be omitted. Of course, providing the foundation section 120 and connecting the trapping body 1 to the foundation section 120 is preferable in order to improve the strength of the weir 100. Alternatively, parts of each steel pipe 31a, 32a, and 4a may be connected to the connector 33 using fasteners such as bolts. [Explanation of symbols]

[0065] 1 Captured body 2 Upstream Unit 3 Downstream Unit 4 Connecting part 4a steel pipe 21 Beam section 21a steel pipe 22 Pillar section 22a steel pipe 31 Beam section 31a steel pipe 32 Pillar section 32a steel pipe 33 Connectors 100 Dams 110 Non-overflow section 120 Foundation 111 Opening

Claims

1. A trapping device that allows flowing water from the upper reaches of a river to pass through and captures objects contained in the flowing water, An upstream unit is provided on the upstream side of the river to capture the object, A downstream unit is provided on the downstream side of the river, and is formed by bending its central part so that it protrudes toward the upstream unit, It comprises a connecting portion that connects the upstream unit and the downstream unit, Each end of the downstream unit is fixed to the non-overflow sections constructed on both sides of the trapping body in the direction crossing the river. Each end of the upstream unit is fitted into a sheath pipe provided in the non-overflow section. The upstream unit is provided along the direction of crossing the river and comprises a plurality of beam sections arranged in a line along the height direction, The downstream unit is provided along the direction of crossing the river, is formed by bending its central portion so as to protrude toward the upstream unit, and comprises a plurality of beams arranged in a line along the height direction. The beam portion of the downstream unit is provided at the same height as the beam portion of the upstream unit. The connecting section connects the beam section of the upstream unit and the beam section of the downstream unit, which are facing each other along the direction of river flow and located at the same height. A capture body characterized by the following features.

2. The capture body according to claim 1, characterized in that the downstream unit comprises a plurality of column portions connecting the plurality of beam portions.

3. The capture body according to claim 1 or 2, characterized in that the upstream unit comprises a plurality of column portions connecting the plurality of beam portions.

4. A trapping device that allows flowing water from the upper reaches of a river to pass through and captures objects contained in the flowing water, An upstream unit is provided on the upstream side of the river, which captures the object and is formed by bending so that at least its central portion protrudes toward the upstream side of the river, A downstream unit is provided on the downstream side of the river and is formed by bending at least its central portion so as to protrude toward the upstream unit, It comprises a connecting portion that connects the upstream unit and the downstream unit, The ends of the upstream unit and the downstream unit are fixed to non-overflow sections constructed on both sides of the trapping body in the direction crossing the river. The aforementioned upstream unit is provided along the direction crossing the river, is formed by bending its central portion so as to protrude upstream of the river, and comprises a plurality of beam sections arranged in a line along the height direction. The downstream unit is provided along the direction of crossing the river, is formed by bending its central portion so as to protrude toward the upstream unit, and comprises a plurality of beams arranged in a line along the height direction. The beam portion of the downstream unit is provided at the same height as the beam portion of the upstream unit. The connecting section connects the beam section of the upstream unit and the beam section of the downstream unit, which are facing each other along the direction of river flow and located at the same height. A capture body characterized by the following features.

5. The capture body according to claim 4, characterized in that the downstream unit comprises a plurality of column portions connecting the plurality of beam portions.

6. The capture body according to claim 4 or 5, characterized in that the upstream unit comprises a plurality of beam sections, each having a first straight section provided along the direction crossing the river and formed to extend in a straight line, and a second straight section, one end of which is connected to the end of the first straight section and the other end of which is attached to the non-overflow section downstream of the first straight section.

7. The capture body according to any one of claims 4 to 6, characterized in that the upstream unit comprises a plurality of column portions connecting the plurality of beam portions.

8. A dam comprising a trapping body as described in any one of claims 1 to 7, A pair of non-overflow sections protruding from both banks of the river, An opening provided between the pair of non-overflow sections, The aforementioned opening is provided with a capturing body that allows flowing water from the upper reaches of the river to pass through and captures objects contained in the flowing water, A dam characterized by having the following features.

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