Installation structure of driftwood trapping fence

Abstract

This invention provides a driftwood trapping fence installation structure that is easy to install, economical, and excellent at capturing driftwood, allowing for stable and reliable installation of the fence, and enabling the capture of driftwood that is flowing down the river and trying to get behind it with a simple and reliable structure. [Solution] A base member 9(15) is integrally provided on the upstream side wall portion 12 of the water passage portion 11 of the impermeable weir 10, and a plurality of steel column members 2, 5 constituting the driftwood trapping fence 1 are erected on the base member 9(15). The driftwood trapping fence 1 comprises one or more steel column members 2 provided in the upstream front direction of the water passage portion 11 of the weir 10, two or more steel column members 2 provided in the upstream front direction of both sleeve portions 13 of the weir 10, and one or more steel column members 5 for preventing driftwood from going around, provided between the steel column members 2 provided at both ends of the steel column members 2 and the both sleeve portions 13 of the weir 10.

Description

Technical Field

[0001] This invention belongs to the technical field of a structure in which a driftwood capture fence made of steel column members is installed on the upstream side of an impermeable weir (hereinafter sometimes simply abbreviated as "weir") constructed in the transverse direction of a river for the purpose of sand prevention, mountain governance, etc. Note that the weir may be either an existing one or a newly constructed one.

Background Art

[0002] In view of recent driftwood disasters, the installation of new driftwood capture facilities is desired from the perspective of disaster prevention and mitigation. However, the suitable sites for facility installation are decreasing, and therefore, there is a demand for effective utilization (function improvement) of the weir (existing weir), such as a request to improve the weir so as to add a driftwood capture function. For example, as a means of improving an existing impermeable weir to add a driftwood capture function, techniques such as making a notch or raising the height of the weir are considered, but such techniques have been pointed out to have the problem that large-scale work is required.

[0003] Therefore, as shown in Patent Document 1, a technique of installing a capture body on a sand deposition area upstream of the weir is disclosed. According to this technique, it is recognized that the driftwood capture body can be installed without the need for large-scale work such as making a notch or raising the height of the weir, so that the construction cost and time can be suppressed. However, the technique according to Patent Document 1 has a structure in which a driftwood capture fence is installed on a sand deposition area, and thus there are problems such as concerns about the destabilization and even overturning of the capture body (driftwood capture fence) due to insufficient support force of the ground (floor surface) and ground erosion caused by water discharge.

[0004] Therefore, in view of the above problems, as shown in Patent Documents 2 and 3, a technique of directly installing a capture body on the upstream wall surface of the weir is disclosed.

[0005] According to the aforementioned Patent Documents 2 and 3, not only is there no need for large-scale work such as notching or raising the embankment, but there is also no need to install driftwood trapping fences on the sand deposit, so the cost and time of construction can be reduced, and it is possible to install highly stable driftwood trapping fences, among other advantages. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2017-072020 [Patent Document 2] Japanese Patent Publication No. 2020-112027 [Patent Document 3] Japanese Patent Publication No. 2022-060378 [Overview of the project] [Problems that the invention aims to solve]

[0007] The technology described in Patent Document 2 has a structure in which the capture bodies (driftwood capture fences) are arranged side by side horizontally, and therefore has the problem that it cannot capture driftwood that is flowing down the river (the widthwise end) and trying to go around to the back. The technology described in Patent Document 3 is expected to capture driftwood that flows down the river (the widthwise end) of the capture body and tries to wrap around to the back by installing a lateral beam (beam member) between the capture body provided at both ends and the corresponding wall surface of the weir. However, because one end of the lateral beam (beam member) is fixed to the wall surface of the weir sleeve with anchor bolts and nuts, it requires precise work, is very troublesome, and is very uneconomical in terms of cost. It is also conceivable to replace the lateral beam (beam member) with a vertical column member to capture driftwood that tries to wrap around to the back, but as can be seen clearly in Figure 10b of the same document 3, the second leg portion 33b is inclined, making it difficult and impractical to install on top of it.

[0008] The present invention was devised in view of the problems of the background technology described above, and its purpose is to provide a driftwood capture fence installation structure that is excellent in terms of constructability, economy, and driftwood capture, as it eliminates the need for large-scale work such as cutting out or raising the embankment, allows for the stable and reliable installation of the driftwood capture fence, and can reliably capture driftwood that is flowing down the river (at its widthwise end) and trying to wrap around to the back with a simple structure. [Means for solving the problem]

[0009] As a means to solve the above problems, the driftwood trapping fence installation structure according to claim 1 is a driftwood trapping fence installation structure for an impermeable dam, In the aforementioned impermeable dam, a base member is integrally provided on the upstream wall surface of the water passage section, and a plurality of steel column members constituting the driftwood trapping fence are erected on the base member. The driftwood trapping fence is characterized by comprising one or more steel column members provided in the upstream front direction of the water passage section of the impermeable weir, two or more steel column members provided in the upstream front direction of both sleeve sections of the impermeable weir, and one or more steel column members for preventing driftwood from going around provided between the steel column members provided at both ends of the steel column members and both sleeve sections of the impermeable weir.

[0010] The invention described in claim 2 is characterized in that, in the driftwood trapping fence installation structure described in claim 1, all or part of the adjacent steel column members are connected by a lateral connecting member.

[0011] The invention described in claim 3 is characterized in that, in the installation structure for the driftwood trapping fence described in claim 1, the steel column members provided at both ends and the steel column members for preventing driftwood from going around are connected by a lateral connecting member positioned to ensure clearance between them and the sleeves of the impermeable dam.

[0012] The invention described in claim 4 is characterized in that, in the installation structure of the driftwood trapping fence described in claim 1, the lateral connecting member is provided at a height equivalent to the expected water depth.

[0013] The invention described in claim 5 is characterized in that, in the installation structure for the driftwood trapping fence described in claim 1, the base member is a concrete base, or a steel base comprising a horizontal member and a diagonal member supporting the horizontal member.

[0014] The invention described in claim 6 is characterized in that, in the installation structure for the driftwood trapping fence described in claim 1, the steel column member consists of at least one driftwood trapping support.

[0015] The invention described in claim 7 is characterized in that, in the installation structure for the driftwood trapping fence described in claim 1, the top height of the base member is set to be equal to or less than the bottom height of the water passage section.

[0016] The invention described in claim 8 is characterized in that, in the driftwood trapping fence installation structure described in claim 1, the steel column members are installed with the distance between them set to the smaller of 1 / 2 of the expected maximum or average driftwood length or 3.0 m.

[0017] The invention described in claim 9 is characterized in that, in the driftwood trapping fence installation structure described in claim 1, the height of the driftwood trapping fence is set to be equal to or greater than the water passage height of the water passage section.

[0018] The invention described in claim 10 is characterized in that, in the installation structure for the driftwood trapping fence described in claim 1, the impermeable dam is a newly constructed structure or an existing structure. [Effects of the Invention]

[0019] The driftwood trapping fence installation structure according to the present invention provides the following effects. (1) It can be implemented without the need for large-scale work such as cutting or raising the dam, making it extremely easy to construct and economical. (2) A base member can be constructed on the upstream side wall surface of the water passage part in the weir, and a driftwood catching fence (a plurality of steel column members) can be surely installed stably above it. Therefore, it has the advantages of excellent workability and rich design freedom, and in addition, the driftwood removal work after catching the driftwood can be smoothly carried out. (3) Among the steel column members constituting the driftwood catching fence, the driftwood flowing down the river (the end part in the width direction) and trying to go around behind can be effectively caught with a simple structure by the steel column members provided at both ends and the steel column members for preventing going around provided between the steel column members at both ends and both sleeves of the weir. (4) When the steel column members provided at both ends and the steel column members for preventing going around are connected by a horizontal connecting member positioned with a clearance secured between both sleeves of the weir, all the joining operations that were difficult in the past (refer to the said Patent Document 3) can be omitted, and still, the catching effect of the driftwood trying to go around behind can be realized at the same level as in the past. (5) In summary, an installation structure of a driftwood catching fence excellent in workability, economy, and driftwood catching property can be realized.

Brief Description of the Drawings

[0020] [Figure 1] It is a perspective view showing Example 1 of the installation structure of the driftwood catching fence according to the present invention. [Figure 2] It is a left side view of FIG. 1. [Figure 3] It is a front view of FIG. 1. [Figure 4] It is a plan view of FIG. 1. [Figure 5] It is a perspective view showing Example 2 of the installation structure of the driftwood catching fence according to the present invention. [Figure 6] It is a left side view of FIG. 5. [Figure 7] It is a plan view of FIG. 5. [Figure 8] It is a perspective view showing Example 3 of the installation structure of the driftwood catching fence according to the present invention. [Figure 9] It is a left side view of FIG. 8. [Figure 10] It is a front view of FIG. 8. [Figure 11] This is a plan view of Figure 8. [Figure 12] This is a perspective view showing Embodiment 4 of the driftwood capture fence installation structure according to the present invention. [Figure 13] This is a left side view of Figure 12. [Figure 14] Figure 12 is a front view. [Figure 15] Figure 12 is a plan view. [Figure 16] This is a perspective view showing Embodiment 5 of the driftwood capture fence installation structure according to the present invention. [Figure 17] This is a perspective view showing Embodiment 6 of the driftwood capture fence installation structure according to the present invention. [Figure 18] This is a left side view of Figure 17. [Figure 19] This is a perspective view showing Embodiment 7 of the driftwood capture fence installation structure according to the present invention. [Figure 20] This is a left side view of Figure 19. [Figure 21] This is a perspective view showing variations in foundation concrete. [Figure 22] This is a left side view of Figure 21. [Modes for carrying out the invention]

[0021] The present invention is based on a technical concept that considers how to effectively capture driftwood and other debris using steel column members (driftwood capture fences) without notching or raising the aforementioned impermeable dam, while improving constructability, and in particular how to prevent driftwood flowing down the river (at its widthwise end) from circling around and being washed away with a simple and reliable structure. The following describes an embodiment of the driftwood trapping fence installation structure according to the present invention, based on the drawings. [Examples]

[0022] Figures 1 to 4 show the installation structure of the driftwood trapping fence according to Example 1. The driftwood trapping fence installation structure shown in the illustration is an installation structure for a driftwood trapping fence 1 on an impermeable weir 10, wherein a base member 9 is integrally provided on the upstream side wall surface 12 of the water passage section 11 of the weir 10, and a plurality of steel column members 2 constituting the driftwood trapping fence 1 are erected on the base member 9. The driftwood trapping fence 1 comprises one or more steel column members 2 provided in the upstream front direction of the water passage section 11 of the weir 10, two or more steel column members 2 provided in the upstream front direction of both sleeve sections of the weir (see Figure 3), and one or more (one in the illustrated example) steel column members 5 for preventing driftwood from going around, provided between the steel column members 2 provided at both ends of the steel column members 2 and the sleeve sections 13 of the weir 10.

[0023] In this embodiment 1, the base member 9 is made of concrete, and the top height of the base member 9 is set to be approximately horizontal at the same height (or lower) as the bottom height of the water drainage section 11, as can be clearly seen in Figure 2. The top width of the base member 9 is set to a width that can support the plurality of steel column members 2 and 5, specifically a width that is appropriate for capturing driftwood flowing down the river (for example, about 11m or more). The plurality of steel column members 2 and 5 are of an appropriate size and arrangement for capturing driftwood flowing down the river (at its widthwise end). Incidentally, the reference numeral 11a in the figure indicates the sleeve ends that make up both ends of the water-permeable section 11.

[0024] As can be clearly seen in Figure 2, the base member (concrete base) 9 in this embodiment is formed in a triangular shape with a horizontal top surface when viewed from the side. However, the shape of the base member 9 is not limited to this, and it can of course be formed in a rectangular shape with a horizontal top surface when viewed from the side, as shown in Figures 21 and 22. In short, it is sufficient to have a structure that allows the steel column members 2 and 5 constituting the driftwood trapping fence 1 to be stably installed at a required distance from the dam 10. Incidentally, the base member 9 has a compressive strength of 18 N / mm². 2 It is preferable that the structure be constructed as described above.

[0025] The multiple (five in the illustrated example) steel column members 2 that constitute the driftwood capture fence 1 each consist of a single driftwood capture support 2 of the same shape and size, erected vertically. They are installed with a spacing between them that is less than or equal to half of the expected maximum or average length of driftwood flowing down, or 3.0 m, whichever is smaller (usually around 2.0 to 3.0 m), and are lined up in a row so that they match when viewed from the side (see Figure 2). Furthermore, the distance (shortest distance) between the water passage section 11 and sleeve section 13 of the weir 10 and the steel column member 2 of the driftwood capture fence 1 is set to the smaller of either half of the expected maximum or average driftwood length or 3.0 m (usually around 2.0 to 3.0 m). The same technical concept applies to the following examples 2 to 7.

[0026] In addition, in this embodiment, at least one (one in the illustrated example) steel column member 5 for preventing driftwood from circling around is provided between the steel column members 2 at both ends and the sleeve portions 13 of the weir 10 (approximately in the central part in the illustrated example) in order to effectively capture driftwood that is flowing down the river (at its widthwise end) and trying to circling around behind it. In this embodiment, the steel column member 5 for preventing driftwood from circling around is made of a steel pipe of the same shape and size as the steel column member 2. Incidentally, the diameter (φ) of the steel pipes used in the steel column members 2 and 5 is preferably in the range of 20 to 50 cm, and the wall thickness of the steel pipes is preferably in the range of 8 to 16 mm. The same technical concept applies to the following Examples 2 to 7.

[0027] The height of the steel column members 2 and 5 (the height of the trap fence) is set to be greater than or equal to the water passage height of the water passage section 11, and is usually set to a height of about 2.0 to 3.0 m. The water passage height refers to the top of the sleeve end 11a, as can be seen in Figure 3. Incidentally, the steel column members 2 and 5 in this embodiment are fixed by an anchor fixing method in which a base plate 8 provided at the lower end is placed on a predetermined part of the foundation concrete 9 and anchor bolts are driven in, but the invention is not limited to this, and it is of course possible to implement it by a support embedding method in which the leg portion of the steel column member 2 is embedded (foundation) in the foundation concrete (not shown). The same technical concept applies to the following embodiments 2 and 3.

[0028] The driftwood trapping fence structure described above is constructed by simultaneously building the dam 10 and the base member (concrete base) 9 together, and then erecting the steel column members 2 and 5 at predetermined locations on the base member 9 using an anchor fixing method or a post embedding method. When constructing the base member 9 on an existing weir 10, reinforcing bars for constructing the base member 9 are installed on the upstream wall surface 12 of the water passage section 11 of the weir 10, and formwork for constructing the base member 9 is formed. Concrete is poured into the formwork, and after curing, the formwork is removed to construct the base member 9. Thereafter, the driftwood trapping fence 1 is constructed by erecting a plurality of steel column members 2 and 5 that constitute the driftwood trapping fence 1 at predetermined locations on the base concrete 9 using an anchor fixing method or a post embedding method. Prior to the installation of the reinforcing bars, surface treatment of the concrete joints to be poured will be carried out, and excavation of the concrete construction area will be carried out when the upstream side of the dam 10 is full of sand, as needed. In addition, measures such as setting up scaffolding will be taken as appropriate when work at height is required. Thus, the dam 10 according to the present invention can be implemented regardless of whether it is a newly constructed structure or an existing structure.

[0029] Therefore, the driftwood trapping fence installation structure described above can be implemented without requiring large-scale work such as cutting or raising the dam 10, making it extremely efficient in terms of constructability and cost-effectiveness. Furthermore, a base member (concrete base) 9 is constructed on the upstream wall surface 12 of the water passage section 11 of the weir 10, and the steel column members 2 and 5 that constitute the driftwood capture fence 1 can be securely installed in a stable state in the open space above it. Therefore, it has the advantages of being easy to construct and having a high degree of design flexibility, as well as enabling smooth removal of driftwood after it has been captured. Furthermore, the aforementioned steel column member 5 for preventing driftwood from circling around allows for the effective capture of driftwood that is flowing down the river (at its widthwise end) and attempting to circling around behind it, using a simple structure. [Examples]

[0030] Figures 5 to 8 show the installation structure of the driftwood trapping fence according to Example 2. The installation structure of the driftwood trapping fence according to this embodiment 2 differs from that of embodiment 1 in that all (or part) of the adjacent steel column members 2 are connected by lateral connecting members 4, and the steel column members 2 provided at both ends and the steel column members 5 for preventing driftwood from going around are connected by lateral connecting members 6 that ensure a clearance C (approximately 10 cm in the illustrated example) between them and the sleeves 13 of the weir 10. Components similar to those in embodiment 1 are denoted by the same reference numerals and their descriptions are omitted as appropriate. In this embodiment 2, the horizontal connecting members 4 and 6 are made of steel pipes (round steel pipes) that are thinner than the steel column member 1, and are configured to connect the intermediate parts in the height direction of adjacent steel column members 2 and 5 in a substantially horizontal manner.

[0031] The significance of securing a clearance C between the lateral connecting member 6 and both sleeve portions 13 of the weir 10 is that, by deliberately not joining (connecting) the lateral connecting member 6 and both sleeve portions 13 of the weir 10, all of the joining work that was conventionally difficult (see Patent Document 3) can be omitted, while still achieving the same level of effectiveness in capturing driftwood that tries to wrap around to the back.

[0032] Therefore, the driftwood trapping fence installation structure according to this embodiment 2 can be realized without large-scale work such as notching or raising the dam 10, just like in embodiment 1, and the steel column members 2 and 5 constituting the driftwood trapping fence 1 can be reliably installed in a stable state in the open space on the base member (concrete base) 9, and the structure can effectively capture driftwood that is flowing down the river (the widthwise end) and trying to go around to the back with a simple structure thanks to the steel column member 5 for preventing driftwood from going around, so it still produces the same effects as in embodiment 1 (see paragraph

[0029] above). In addition, the driftwood trapping fence installation structure according to this embodiment 2, when viewed from the plan direction (see Figure 7), has a structure in which adjacent steel column members 2 and 5 are connected in a series with lateral connecting members 4 and 6, so that the composite body with the weir 10 forms a roughly frame-shaped pocket P. Therefore, even if the driftwood trapping fence 1 is blocked by driftwood or other floating debris, the river water overflowing from the blocked section flows into the area of ​​the pocket P and passes through the water passage section 11. In other words, the driftwood trapping fence 1 acts as a filter, so there is no risk of the water passage section 11 becoming blocked, and it is possible to maintain a safe and good flow of water. Furthermore, it is preferable to install the aforementioned lateral connecting members 4 and 6 at a height equivalent to the expected flowing water depth, as this allows for more effective capture of driftwood and other floating objects. The same technical concept applies to the following embodiments 3, 6, and 7. [Examples]

[0033] Figures 9 to 11 show the installation structure of the driftwood trapping fence according to Example 3. The installation structure of the driftwood trapping fence according to this embodiment 3 differs from that of embodiment 2 in that, among the steel column members 2, the central part excluding both ends (three in the illustrated example) has one downstream support diagonal member 2a attached to one driftwood trapping post 2. Also, the steel column member 5 for preventing driftwood from wrapping around differs in that one support diagonal member 5a is attached to one driftwood trapping post 5. Components similar to those in embodiment 2 are denoted by the same reference numerals and their descriptions are omitted as appropriate.

[0034] Specifically, the downstream support diagonal member 2a is connected to the middle section of the driftwood capture support column 2 by welding or other joining means, in a position inclined downward from the upstream side to the downstream side, and as a whole, it is formed in a roughly T-shape with its legs spreading in the direction of river flow. On the other hand, the support diagonal member 5a is connected to the middle section of the driftwood capture support column 5 by welding or other joining means, in a position inclined downward toward the inward side of the pocket P, and as a whole, it is formed in a roughly T-shape with its legs spreading in the width direction of the river. In this embodiment, the steel column members 2 and 5 formed in a roughly T-shape are of the same shape and size, but the design is not limited to this, and can be appropriately modified according to the respective structural design.

[0035] Therefore, the driftwood trapping fence installation structure according to this embodiment 3 can be realized without large-scale work such as notching or raising the dam 10, just like in embodiment 2, the steel column members 2 and 5 constituting the driftwood trapping fence 1 can be reliably installed in a stable state in the open space on the base member (concrete base) 9, the steel column member 5 for preventing driftwood from going around can effectively capture driftwood that is flowing down the river (the widthwise end) and trying to go around to the back with a simple structure, and when viewed from the planar direction (see Figure 11), it still exhibits a structure that forms a roughly frame-shaped pocket P, so it also produces the same effects as in embodiment 2 (see paragraph

[0032] above). In addition, compared to the above embodiment 2, the structure is reinforced by newly providing the downstream support diagonal member 2a and the support diagonal member 5a. Therefore, compared to the above embodiment 2, it is possible to realize steel column members 2 and 5, and consequently the driftwood capture fence 1, that have higher strength, rigidity, and durability. [Examples]

[0036] Figures 12 to 15 show the installation structure of the driftwood trapping fence according to Example 4. The driftwood trapping fence installation structure according to this embodiment 4 differs from embodiments 1 to 3 in that, instead of using a concrete base 9 for the base member 4, it is implemented using a steel base 15 equipped with a horizontal member 15a and a diagonal member (bracing member) 15b that supports the horizontal member 15a from below. Components similar to those in embodiment 1 are denoted by the same reference numerals and their descriptions are omitted as appropriate.

[0037] In this embodiment 4, the horizontal member 15a constituting the steel base 15 is provided with a vertically upward projection for flange joining with the steel column member 2 (and 5), and is formed by welding one end together with the diagonal member 15b. The corresponding protruding portions of the driftwood-catching support posts 2 (and 5) of the steel column members 2 (and 5) are flange-jointed and fixed to the upstream wall surface 12 of the weir 10 by anchor bolts via base plates 14 provided at the other ends (base ends) of the horizontal member 15a and diagonal member 15b. Incidentally, in this embodiment, the structure of the steel base 15 applied to the steel column members 2 provided at both ends and the steel column members 2 provided in the central part excluding both ends differs in the presence or absence of vertically upward protruding parts to which the steel column members 5 for preventing drifting are joined. However, as can be clearly seen in Figure 13, the driftwood capture fence 1 is constructed by installing them so that they match when viewed from the side. The form of the steel base 15 shown in the illustration is not limited to this example, and the design can be modified as appropriate, provided that it has sufficient strength and rigidity to stably support the steel column members 2 (and 5) in a cantilevered state. Furthermore, in this embodiment, the diameter (φ) of the steel pipes used for the horizontal members 15a and diagonal members 15b that constitute the steel base 15 is the same size as that of the steel column members 2 and 5, preferably within the range of 20 to 50 cm and a steel pipe wall thickness of 8 to 16 mm. The same technical concept applies to the following embodiments 5 to 7.

[0038] Therefore, the driftwood trapping fence installation structure according to this embodiment 4 can be realized without large-scale work such as notching or raising the dam 10, just like in embodiment 1, and the steel column members 2 and 5 constituting the driftwood trapping fence 1 can be reliably installed vertically in a stable state on the base member (steel base) 15, and the structure exhibits the same effect as embodiment 1, as the steel column member 5 for preventing driftwood from going around allows for the effective capture of driftwood that is flowing down the river (the widthwise end) and trying to go around to the back with a simple structure. [Examples]

[0039] Figure 16 shows the installation structure of the driftwood trapping fence according to Example 5. The installation structure of the driftwood trapping fence according to this embodiment 5 differs from that of embodiment 4 in that a single downstream support diagonal member 2a is attached to multiple (three in the illustrated example) steel column members (driftwood trapping posts) 2 provided in the central part excluding both ends. The same reference numerals are used for members similar to those in embodiment 4, and their descriptions are omitted as appropriate. Specifically, the downstream support diagonal member 2a is connected to the intermediate part of the driftwood capture support column 2 by welding or other joining means, in the same manner as in Embodiment 3 above, with the support angled downward from the upstream side to the downstream side, and the overall structure is formed in a roughly T-shape with the legs splayed outwards in the direction of river flow.

[0040] Therefore, the driftwood trapping fence installation structure according to this embodiment 5 can be realized without large-scale work such as notching or raising the dam 10, just like in embodiment 4, and the steel column members 2 and 5 constituting the driftwood trapping fence 1 can be reliably installed vertically in a stable state on the base member (steel base) 15, and the structure exhibits the same effect as embodiment 4, as the steel column member 5 for preventing driftwood from going around allows for the effective capture of driftwood that is flowing down the river (the widthwise end) and trying to go around to the back with a simple structure. In addition, compared to the above embodiment 4, the structure is reinforced by newly providing the downstream support diagonal member 2a, so that a steel column member 2 with higher strength and rigidity and durability, and consequently a driftwood trapping fence 1 can be realized compared to the above embodiment 4. [Examples]

[0041] Figures 17 and 18 show the installation structure of the driftwood trapping fence according to Example 6. The installation structure of the driftwood trapping fence according to this embodiment 6 differs from that of embodiment 4 in that all (or some) of the adjacent steel column members 2 are connected by lateral connecting members 4, and the steel column members 2 provided at both ends and the steel column members 5 for preventing driftwood from going around are connected by lateral connecting members 6 that secure a clearance C (approximately 10 cm in the illustrated example) between them and the sleeves 13 of the weir 10. Components similar to those in embodiment 4 are denoted by the same reference numerals and their descriptions are omitted as appropriate. In this embodiment 6, the horizontal connecting members 4 and 6 are made of steel pipes (round steel pipes) that are thinner than the steel column member 1, and are configured to connect the intermediate parts in the height direction of adjacent steel column members 2 and 5 in a substantially horizontal manner.

[0042] The significance of securing a clearance C between the lateral connecting member 6 and both sleeve portions 13 of the weir 10 is that, by deliberately not joining (connecting) the lateral connecting member 6 and both sleeve portions 13 of the weir 10, all of the joining work that was conventionally difficult (see Patent Document 3) can be omitted, while still achieving the same driftwood capture effect as in the conventional method, preventing driftwood from going around to the back.

[0043] Therefore, the driftwood trapping fence installation structure according to this embodiment 6 can be realized without large-scale work such as notching or raising the dam 10, just like in embodiment 4, and the steel column members 2 and 5 constituting the driftwood trapping fence 1 can be reliably installed in a stable state in the open space on the base member (concrete base) 9, and the structure can effectively capture driftwood that is flowing down the river (the widthwise end) and trying to go around to the back with a simple structure thanks to the steel column member 5 for preventing driftwood from going around, so it still produces the same effects as in embodiment 4 (see paragraph

[0038] above). In addition, the driftwood trapping fence installation structure according to this embodiment 6 involves connecting adjacent steel column members 2 and 5 in a series with lateral connecting members 4 and 6, so that the composite body with the weir 10 forms a roughly frame-shaped pocket P (see with reference to Figure 7). Therefore, even if the driftwood trapping fence 1 is blocked by driftwood or other floating debris, the river water overflowing from the blocked section flows into the area of ​​the pocket P and passes through the water passage section 11. In other words, the driftwood trapping fence 1 acts as a filter, so there is no risk of the water passage section 11 becoming blocked, and it is possible to maintain a safe and good water flow. [Examples]

[0044] Figures 19 and 20 show the installation structure of the driftwood trapping fence according to Example 7. The driftwood trapping fence installation structure according to this embodiment 7 differs from that of embodiment 6 in that a single downstream support diagonal member 2a is attached to multiple (three in the illustrated example) steel column members (driftwood trapping posts) 2 provided in the central part excluding both ends. Components similar to those in embodiment 6 are denoted by the same reference numerals, and their descriptions are omitted as appropriate. Specifically, the downstream support diagonal member 2a is connected to the intermediate part of the driftwood capture support column 2 by welding or other joining means, in a position where it is inclined downward from the upstream side to the downstream side, and the overall structure is formed in a roughly T-shape with its legs splayed outwards in the direction of river flow.

[0045] Therefore, the driftwood trapping fence installation structure according to this embodiment 7 can be realized without large-scale work such as notching or raising the dam 10, just like in embodiment 6, the steel column members 2 and 5 constituting the driftwood trapping fence 1 can be reliably installed vertically in a stable state on the base member (steel base) 15, the steel column member 5 for preventing driftwood from wrapping around can effectively capture driftwood that is flowing down the river (the widthwise end) and trying to wrap around to the back with a simple structure, and since it still exhibits a structure that forms a roughly frame-shaped pocket P (see with reference to Figure 11), it also produces the same effects as in embodiment 6 (see paragraph

[0043] above). In addition, compared to the above embodiment 6, the structure is reinforced by newly providing the downstream support diagonal member 2a, so that a steel column member 2 with higher strength and rigidity and superior durability, and consequently a driftwood trapping fence 1 can be realized compared to the above embodiment 6.

[0046] Although the above-described embodiments 1 to 7 have been explained based on the drawings, it should be noted that the present invention is not limited to the illustrated examples and includes design modifications and variations in application that are ordinarily performed by those skilled in the art, without departing from the technical idea. For example, in the weir 10 of Examples 1 to 7, the bottom width of the water passage section 11 is approximately 5m, and the width of the side openings 11a is approximately slightly less than 1m each, but of course, the design can be changed as appropriate according to the structural design. The width of the foundation concrete 9 is often 10 to 20m in the width direction of the river, but of course, the design can be changed as appropriate according to the structural design. Furthermore, although the steel column members 2 and 5 in Examples 1 to 7 are made of round steel pipes, they can also be constructed using square steel pipes or H-shaped steel. The number and size of the steel column members 2 and 5 used are, of course, not limited to those described above. The design can be modified as appropriate based on factors such as the expected length of driftwood, the scale of the weir 10, the width of the water passage section 11, the characteristics of the river during floods (expected water level, expected flow rate, width of driftwood flow), and driftwood capture simulations using image analysis. The sleeve portion 13 of the dam in Examples 1 to 7 forms a sleeve slope, but of course, it is not limited to this and can also be applied to dams without a sleeve slope. [Explanation of Symbols]

[0047] 1. Driftwood trapping fence 2. Steel column members (driftwood capture support posts) 2a Downstream support diagonal member 4. Horizontal connecting material 5. Steel column members for preventing drifting (driftwood capture support posts) 5a Support diagonal members 6. Horizontal connecting material 8 Base Plate 9. Base members (concrete base) 10 Impermeable Dam 11 Water-permeable section 11a Sleeve edge 12 Upstream side wall section 13 Sleeves 14 Base Plate 15. Base components (steel base) 15a Horizontal material 15b Diagonal material C Clearance P Pocket

Claims

1. A structure for installing a driftwood trapping fence for an impermeable dam, In the aforementioned impermeable dam, a base member is integrally provided on the upstream wall surface of the water passage section, and a plurality of steel column members constituting the driftwood trapping fence are erected on the base member. The driftwood trapping fence is characterized by comprising one or more steel column members provided in the upstream front direction of the water passage section of the impermeable weir, two or more steel column members provided in the upstream front direction of both sleeve sections of the impermeable weir, and one or more steel column members for preventing driftwood from going around provided between the steel column members provided at both ends of the steel column members and both sleeve sections of the impermeable weir, wherein the installation structure for the driftwood trapping fence is characterized by comprising one or more steel column members provided in the upstream front direction of the water passage section of the impermeable weir, two or more steel column members provided in the upstream front direction of both sleeve sections of the impermeable weir, and one or more steel column members for preventing driftwood from going around provided between the steel column members provided at both ends of the steel column members.

2. The installation structure for a driftwood trapping fence according to claim 1, characterized in that all or part of the adjacent steel column members are connected by a lateral connecting member.

3. The driftwood trapping fence installation structure according to claim 1, characterized in that the steel column members provided at both ends and the steel column members for preventing driftwood from wrapping around are connected by lateral connecting members positioned to ensure clearance between them and the sleeves of the impermeable dam.

4. The driftwood trapping fence installation structure according to claim 2 or 3, characterized in that the aforementioned lateral connecting member is installed at a height equivalent to the expected flowing water depth.

5. The installation structure for a driftwood trapping fence according to claim 1, characterized in that the base member is a concrete base or a steel base comprising a horizontal member and a diagonal member supporting the horizontal member.

6. The driftwood trapping fence installation structure according to claim 1, characterized in that the steel column member consists of at least one driftwood trapping support.

7. The driftwood trapping fence installation structure according to claim 1, characterized in that the top height of the base member is set to be equal to or less than the bottom height of the water passage section.

8. The driftwood trapping fence installation structure according to claim 1, characterized in that the steel column members are installed with the spacing between them set to the smaller of 1 / 2 of the expected maximum or average driftwood length or 3.0 m.

9. The driftwood trapping fence installation structure according to claim 1, characterized in that the height of the driftwood trapping fence is set to be equal to or greater than the water passage height of the water passage section.

10. The installation structure for a driftwood trapping fence according to claim 1, characterized in that the impermeable dam is a newly constructed structure or an existing structure.

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