Steel slit dam

Abstract

To provide a steel slit dam that is economical, safe (quality), and easy to construct by realizing a structure that prevents overflowing soil, stones, driftwood, etc. from falling and colliding with downstream pillar materials when soil, stones, driftwood, etc. overflow a top of the steel slit dam, and further, a steel slit dam that can be used as a dam known as a high dam.SOLUTION: In a steel slit dam 10 constructed three-dimensionally by connecting upstream side pillars 1 and downstream side pillars 2 with horizontal ties 3 and vertical ties 4, downstream side pillars 2A, which are provided at least at both ends of the river width direction, are provided with a downward incline from the upstream side to the downstream side. The other downstream side pillars 2B are provided vertically. The upper end position of the downstream side pillars 2 is set lower than the upper end position of the upstream side pillars 1. Vertical ties 4H provided at a top are provided with the downward incline from the upstream side to the downstream side.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] This invention belongs to the technical field of steel slit dams (also called steel permeable sabo dams) which are constructed in mountain valleys, rivers, etc. to capture boulders and driftwood generated during debris flows and major floods, or to dampen (reduce the energy of) debris flows to prevent disasters. [Background technology]

[0002] Regarding steel slit dams, a wide variety of proposals have already been made and many examples exist, as shown in Patent Documents 1 and 2 below.

[0003] Patent Document 1 discloses a trapping body (steel slit dam) 1 for trapping an object flowing from the upstream of a river, the trapping body comprising: a plurality of first pillar sections 10 arranged side by side at a predetermined interval from each other in the width direction of the river so as to incline from the base end to the tip end toward the upstream side of the river; a plurality of second pillar sections 20 arranged side by side at a predetermined interval in the same arrangement direction as the first pillar sections 10 so as to incline from the base end to the tip end toward the opposite side to the first pillar sections 10 and intersect with the extension direction of the first pillar sections 10; a plurality of third pillar sections 30 arranged side by side at a predetermined interval in the same arrangement direction as the first pillar sections 10 on the opposite side to the first pillar sections 10 with respect to the second pillar sections 20 so as to incline from the base end to the tip end toward the same side as the second pillar sections 20 and intersect with the extension direction of the first pillar sections 10; and a pillar connecting section 90 connecting the second pillar sections 20 and the third pillar sections 30 to each other (see claim 1, the description in Figs. 1 to 2C, etc.). Specifically, the capture body 1 in the illustrated example has a plurality of pillars 10, 20, 30, beams 40, 50, 60, an extension 70, and pillar connecting parts 80, 90. The pillars 10, 20, 30 extend in the height direction of the sabo dam 100, and the beams 40, 50, 60 intersect the pillars 10, 20, 30 and extend in the width direction of the river (see paragraph

[0026] of the same document 1). The extension portion 70 extends downstream from the steel pipe column 21 and the steel pipe beam 51. The extension portion 70 has a plurality of extension steel pipes 71, 72 and a plurality of beam steel pipes 73. The extension steel pipes 71, 72 and the beam steel pipe 73 are formed of steel pipe material (see paragraph

[0043] of the same document 1). As shown in Figures 2C, 5A, etc., the extension steel pipe 71 is provided on the tip side of the steel pipe column 21 in the height direction. The extension steel pipe 71 extends downward toward the downstream side in the horizontal direction of the river. The extension steel pipe 72 is provided between the steel pipe columns 21 in the uppermost steel pipe beam 51 in the height direction. The extension steel pipe 72 extends downward toward the downstream side in the horizontal direction of the river. The tips of the extension steel pipes 71, 72 protrude at least downstream further than the base end of the steel pipe column 11 (see paragraph

[0044] of the same document 1).

[0004] Patent Document 2 discloses a steel slit dam consisting of a slit structure 2 installed in the width direction of a river, the slit structure 2 comprising pillars 3, 4 erected at a distance between an upstream position A and a downstream position B in the direction of the river flow, an upstream horizontal tie member 5 connecting adjacent upstream pillars 3, 3, and a top eaves member 6 having one end joined near the upper end of the upstream pillar 3 and the other end supported by the downstream pillar 4 with a configuration in which the upper end position of the downstream pillar 4 is lower than the upper end position of the upstream pillar 3, and the top eaves member 6 is inclined at a gradient θ descending from the upstream side to the downstream side (see claim 1, the description of the entire drawing, etc.). In short, the steel slit dam of Patent Document 2 is equipped with a slit structure 2 having one end joined near the upper end of the upstream pillar 3 and the other end configured to extend downstream beyond the downstream pillar 4, and is provided with a top eaves member 6 supported by the downstream pillar 4, thereby realizing a configuration that reduces the possibility of boulders, driftwood, etc. flowing down the upper surface of the pile up falling and colliding with the downstream pillar 4, thereby presenting a structure that effectively prevents damage to the inclined downstream pillar 4. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2023-41257 [Patent Document 2] Patent No. 2021-143583 Summary of the Invention [Problem to be solved by the invention]

[0006] The capture body 1 according to the above-mentioned Patent Document 1 has a configuration in which all of the downstream side pillar portions (first pillar portions) 10 are inclined, and therefore has the following problems. That is, the tips of the extension steel pipes 71, 72 constituting the extension portion 70 are configured to extend downstream from the base end of the steel pipe column 11 located at the most downstream side among the downstream side column portions 10, so that the extension steel pipes 71, 72 are supported in a cantilevered state. Therefore, if large soil or rocks fall on the extension steel pipes 71, 72 with an impact, a large bending moment will act on the extension steel pipes 71, 72 with an impact due to the impact, and there is a concern that they may break. This concern became more pronounced as the height of the steel pipe column 11, and therefore the downstream column section 10, increased, as the width dimension (horizontal projection area) of the inclined downstream column section 10 increased, and as a result, the protrusion dimensions of the extended steel pipes 71, 72 increased, posing a problem.

[0007] The steel slit dam of Patent Document 2 is configured so that the top eaves member 6 protrudes downstream further than the downstream support pillar 4, and therefore the protruding top eaves member 6 is supported in a cantilevered state, similar to the extending steel pipes 71, 72 of Patent Document 1.

[0008] If the downstream column section (first column section) 10 according to Patent Document 1, particularly the steel pipe column 11 (even one column) could be installed in a vertical position and the entire capture body (steel slit dam) 1 could be constructed structurally in a stable manner, not only would the width dimension (horizontal projection area) of the steel pipe column 11 be minimized, but the overhang dimensions of the extending steel pipes 71, 72 could also be minimized, which would clearly be beneficial in that it would be possible to realize a capture body 1 that is economical and safe. It is also clear that joining in a vertical position is easier and more superior in terms of construction (work) than joining in an inclined position. Similarly, if the downstream support pillar 4 according to Patent Document 2 (even just one pillar) could be installed in a vertical position and the entire steel slit dam 1 could be constructed in a stable structure, not only would the width dimension (horizontal projection area) of the downstream support pillar 4 be minimized, but the overhang dimension of the top eaves member 6 could also be minimized, clearly showing benefits such as realizing a capture body 1 that is economical and safe. It is also clear that joining in a vertical position is easier and more superior in terms of construction (work) than joining in an inclined position.

[0009] However, since the downstream column section 10 including the steel pipe column 11 according to Patent Document 1 is configured to be directly joined to the inclined second column section 20, even if one tries to join the steel pipe column 11 in a vertical position, the angle formed with the second column section 20 will inevitably be an acute angle, making construction (joining work) difficult and also making it difficult to construct the entire capture body (steel slit dam) 1 in a structurally stable manner. Furthermore, as disclosed in Patent Document 2, conventional steel slit dams are typically configured so that when the upstream support pillar 3 is inclined, the downstream support pillar 4 is also inclined to match it, spreading out like a compass, and there is no technical idea of ​​arranging only the downstream support pillar 4 vertically.

[0010] Therefore, the present invention has been devised in consideration of the problems in the background technology described above, and its object is to provide a steel slit dam that is economical, safe (quality) and easy to construct, and that can even be used to realize a dam known as a high dam, by configuring at least the downstream pillars at both ends of the river in the direction of the river width so that they are inclined downward from the upstream side to the downstream side, and the other downstream pillars are arranged vertically, etc., thereby realizing a structure that prevents boulders, driftwood, etc. flowing down the upper surface of the pile from falling and colliding with the downstream pillars. [Means for solving the problem]

[0011] As a means for solving the above problems, the steel slit dam according to the invention described in claim 1 is a three-dimensional steel slit dam constructed by connecting upstream and downstream columns with horizontal and vertical tie members, The downstream pillars installed at least at both ends of the river in the width direction are arranged with a downward incline from the upstream side to the downstream side, and the other downstream pillars are arranged vertically.

[0012] The invention described in claim 2 is characterized in that, in the steel slit dam described in claim 1, the upper end position of the downstream column is set lower than the upper end position of the upstream column, and the vertical connecting member at the topmost stage is arranged at a downward incline from the upstream side to the downstream side.

[0013] The invention described in claim 3 is characterized in that, in the steel slit dam described in claim 1, the vertical connecting member provided at the top stage is an eave-shaped vertical connecting member having one end joined to the upper end of the upstream pillar and the other end configured to protrude downstream in an eave-like manner beyond the downstream pillar and be supported by the downstream pillar.

[0014] The invention described in claim 4 is characterized in that, in the steel slit dam described in claim 3, the eave-shaped vertical connecting members are set to a length that covers at least half of the downstream column member located directly below them, when viewed from a planar direction.

[0015] The invention described in claim 5 is characterized in that, in the steel slit dam described in claim 3 or 4, the eave-shaped vertical connecting members are provided with fall prevention members extending to adjacent vertical connecting members. Effect of the Invention

[0016] The steel slit dam of the present invention has the following advantages. (1) The downstream pillar that constitutes the steel slit dam is implemented by combining a vertical downstream pillar with an inclined downstream pillar, so that it is possible to economically and rationally realize a structure that is less likely to cause boulders or driftwood flowing down the upper surface of the pile to fall and collide with the downstream pillar. Therefore, damage to the downstream pillar and, by extension, the steel slit dam can be prevented as much as possible, so a steel slit dam with excellent economy, safety (quality), ease of construction, and maintainability can be realized. (2) By installing the downstream pillars that make up the steel slit dam vertically and minimizing the width dimension (horizontal projection area), it is possible to shorten the length of the connecting members and other components arranged inside the steel slit dam and to reduce the number of them used, which makes it more economical. (3) The downstream column that constitutes the steel slit dam is implemented by combining a vertical downstream column with an inclined downstream column. Therefore, compared to conventional steel slit dams in which both the upstream and downstream columns are constructed with diagonal columns, the width (horizontal projection area) can be efficiently reduced while the structural height can be increased. It is also possible to realize a steel slit dam that can be used to build dams known as high dams. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a perspective view showing a first embodiment of a steel slit dam according to the present invention. [Diagram 2] FIG. 2 is a plan view of FIG. [Diagram 3] 2 is a right side view showing a frame structure including the inclined downstream-side pillar 2A of FIG. 1. FIG. [Figure 4]2 is a right side view showing a frame structure including a vertical downstream-side pillar 2B in FIG. 1. FIG. [Diagram 5] FIG. 11 is a perspective view showing a second embodiment of the steel slit dam according to the present invention. [Figure 6] FIG. 6 is a plan view of FIG. 5. [Figure 7] FIG. 6 is a right side view showing a frame structure including the inclined downstream-side pillar 2A of FIG. 5. [Figure 8] FIG. 6 is a right side view showing a frame structure including the vertical downstream-side pillar 2B of FIG. 5. [Figure 9] FIG. 11 is a perspective view showing a third embodiment of the steel slit dam according to the present invention. [Figure 10] FIG. 10 is a plan view of FIG. [Figure 11] FIG. 10 is a right side view showing a frame structure including the inclined downstream-side pillar 2A of FIG. 9. [Figure 12] FIG. 10 is a right side view showing a frame structure including the vertical downstream-side pillar 2B of FIG. 9. [Figure 13] FIG. 11 is a perspective view showing a fourth embodiment of the steel slit dam according to the present invention. [Figure 14] FIG. 14 is a plan view of FIG. [Figure 15] FIG. 11 is a perspective view showing a fifth embodiment of the steel slit dam according to the present invention. [Figure 16] FIG. 16 is a plan view of FIG. [Figure 17] FIG. 11 is a perspective view showing a sixth embodiment of a steel slit dam according to the present invention. [Figure 18] FIG. 18 is a plan view of FIG. [Figure 19] FIG. 11 is a perspective view showing a seventh embodiment of the steel slit dam according to the present invention. [Figure 20] FIG. 20 is a plan view of FIG. 19. [Figure 21] FIG. 11 is a perspective view showing Example 8 of the steel slit dam according to the present invention. [Figure 22] FIG. 22 is a plan view of FIG. 21. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Next, an embodiment of a steel slit dam according to the present invention will be described with reference to the drawings. EXAMPLES

[0019] As shown in Figures 1 to 4, the steel slit dam 10 of the present invention is a steel slit dam 10 constructed three-dimensionally by connecting an upstream pillar 1 and a downstream pillar 2 with horizontal tie members 3 and vertical tie members 4, and at least the downstream pillar members 2A located at both ends of the river in the river width direction are arranged with a downward incline from the upstream side to the downstream side, and the other downstream pillar members 2B are arranged vertically. Here, the horizontal tie members 3 refer to substantially horizontal members that connect adjacent upstream pillars 1 or adjacent downstream pillars 2. On the other hand, the vertical tie members 4 refer to substantially horizontal members or diagonal members that connect the upstream pillars 1 and downstream pillars 2 at the front and rear.

[0020] Specifically, the steel slit dam 10 is constructed as a single unit (or multiple units lined up) along the width of the river on a foundation (concrete foundation) 20 poured into the bottom between concrete dams (not shown) constructed in a river in a mountainous area, as shown in Figure 1. In the illustrated example, the steel slit dam 10 is constructed three-dimensionally by erecting four upstream pillars 1 and four downstream pillars 2 at intervals (for example, about 0.5 to 2.0 m) and connecting them with multiple horizontal tie members 3 and vertical tie members 4.

[0021] As shown in Figs. 1 to 4, the four upstream-side pillars 1 are arranged side by side at substantially the same inclination angle in the direction ascending toward the downstream side. On the other hand, of the four downstream pillars 2, the two downstream pillars 2A, which are located at both ends of the river in the width direction, are arranged at a downward incline from the upstream side to the downstream side, as shown in Figure 3, and the other two downstream pillars 2B are arranged vertically, as shown in Figure 4. In addition, in this embodiment, the upper end position of the downstream column material 2 is set lower than the upper end position of the upstream column material 1, and the connecting material 4H located at the uppermost stage of the vertical connecting materials 4 is arranged at a downward incline from the upstream side to the downstream side.

[0022] In this embodiment, the two vertical downstream pillars 2B are each erected with their lower ends buried in the foundation 20, and are arranged in a position that rises vertically from the foundation 20, and the two downstream pillars 2A located at both ends on the left and right are each erected with their lower ends buried in the foundation 20, and are arranged in an inclined position from the foundation 20 toward a position corresponding to the end of the vertical tie 4H that is installed at the topmost level of the vertical tie 4. Incidentally, the symbol 5 in the figure denotes a support material, and in this embodiment, it is configured to rise from the foundation 20 to the middle part of the corresponding upstream pillar material 1, slanting upward toward the upstream side, and is implemented with a total of four pieces, two long and two short.

[0023] In addition, the number or sizes of the upstream pillars 1, downstream pillars 2, horizontal tie members 3, vertical tie members 4, and support members 5 used are of course not limited to these and can be appropriately changed depending on the structural design. In this invention, the structural design refers to the maximum size of the expected soil and rocks (boulders) and the maximum length of driftwood, as well as the size of the opening (foundation 20), the characteristics of the river during floods (expected water level, expected flow rate, width of driftwood flowing down), and a simulation of the capture of soil and rocks, driftwood, etc. through image analysis. There are various means for installing the pillar materials 1, 2 on the foundation 20. Although detailed drawings are omitted in this embodiment, the lower end portion to which the base plate is attached is embedded and erected in the foundation 20. Alternatively, the lower end portion can be erected in a sheath pipe that is embedded in the foundation 20 beforehand. In the illustrated example, the upper surface of the foundation 20 is horizontal, but this is not limited to this, and the foundation may be inclined along the riverbed gradient. Furthermore, each of the above-mentioned pillar materials 1, 2, connecting materials 3, 4, and supporting material 5 can also be implemented using a single steel pipe, but in this embodiment, as shown in the example, they are implemented as a divisible structure (can be in two or more places) in which a pair of flanges provided on the end faces of opposing steel pipes are joined by bolting (flange joining).

[0024] Therefore, the steel slit dam 10 according to this embodiment has the following advantages. That is, by implementing a configuration in which the two central downstream columns 2B of the four downstream columns 2 are vertically arranged, the length of the two central downstream columns 2B can be shortened and the width dimension (horizontal projection area) of the downstream columns 2B can be reduced compared to the case in which all four downstream columns 2 are inclined. As a result, it is possible to shorten the components such as the vertical tie members 4 arranged inside the steel slit dam 10 and reduce the number of them used. Therefore, it is economical. Since joining to the other material in a vertical position is easier than joining to the other material in an inclined position, it is also easier to work with. The downstream pillar 2 that constitutes the steel slit dam 10 is implemented by combining the vertical downstream pillar 2B and the inclined downstream pillar 2A, which makes it possible to economically and rationally realize a structure in which boulders, driftwood, etc. flowing down the upper surface of the pile are less likely to fall and collide with the downstream pillar 2. Therefore, damage to the downstream pillar 2 and, in turn, the steel slit dam 10 can be prevented as much as possible, making it possible to realize a steel slit dam 10 that is excellent in terms of economy, safety (quality), ease of construction, and maintainability. Furthermore, compared to conventional steel slit dams in which the upstream and downstream pillars are all constructed at an inclination, it is possible to efficiently reduce the width (horizontal projection area) while increasing the structural height, making it possible to realize a steel slit dam that can also be used to build dams known as high dams. Of the four downstream pillars 2, the two downstream pillars 2A at both ends are implemented in a well-balanced inclined posture, so that the entire steel slit dam 10 can be constructed in a structurally stable manner. In addition, in the steel slit dam of this embodiment, the vertical connecting member 4H at the topmost stage is arranged to be inclined downward from the upstream side to the downstream side, so that overflowing soil, stones, driftwood, etc. flow smoothly and quickly with acceleration without stagnating around the top end of the steel slit dam 10, thereby realizing a configuration that further reduces the possibility of the soil, stones, driftwood, etc. falling and colliding with the downstream pillar 2, thereby realizing a steel slit dam that can extremely effectively prevent damage to the downstream pillar 2.

[0025] For reference, the members constituting the upstream pillar 1, downstream pillar 2, horizontal tie 3, vertical tie 4, and support 5 are mainly made of steel pipes (metal pipes) with an outer diameter of about 400 to 600 mm and a wall thickness of about 9 to 22 mm. The distance (installation width) between the upstream pillar 1 and the downstream pillar 2 can be as small as 2 to 3 m. The overall size of the steel slit dam 10 can be as large as 10 to 12 m in height, and due to the unique configuration of the present invention, it can be as large as 15 m or more, which is called a high dam. In addition, the upstream pillar 1 and downstream pillar 2, which are adjacent to each other, are installed at an incline in a generally V-shape with a space of about 1.5m to 2.0m between their upper ends, as shown in Fig. 3. The reason for providing an appropriate space between the upper end of the upstream pillar 1 and the upper end of the downstream pillar 2 is that, compared to a configuration in which the upper ends of the pillars 1, 2 are directly joined to each other, the stability (safety) of the structure can be increased, and when a debris flow overflows the upstream pillar 1, water and small gravel can escape between the upstream pillar 1 and the downstream pillar 2, effectively separating the soil and water, thereby reducing the force of the debris flow. Incidentally, the inclination angles of the upstream pillar 1 and the downstream pillar 2 in this embodiment are merely an example, and are implemented with an inclination gradient of 0.2 in horizontal length and 1 in vertical height. EXAMPLES

[0026] Next, a steel slit dam 10 according to a second embodiment will be described with reference to Figures 5 to 8. Note that the same members as those in the first embodiment will be given the same reference numerals and the description thereof will be omitted as appropriate. The steel slit dam 10 of this Example 2 differs from the above-mentioned Example 1 mainly in that an eave-shaped vertical tie member 14 is used instead of the tie member 4H provided at the topmost stage of the steel slit dam 10 of Example 1. In other words, the eaves-shaped vertical connecting member 14 has one end joined to the upper end of the upstream pillar 1 by a joining means such as welding, and the other end is configured to protrude in an eaves-like manner downstream from the downstream pillar 2, and is supported by the downstream pillar 2 by a joining means such as welding.

[0027] The eaves-shaped vertical tie members 14 are formed to a length that covers at least half (in this embodiment, the entirety) of the downstream pillar 2 located directly below them when viewed from the planar direction. The eaves-shaped vertical tie members 14 are provided to reduce the possibility that boulders, driftwood, etc. flowing down the upper surface of the pile fall and collide with the downstream pillar 2, and to effectively prevent damage to the downstream pillar 2 and, in turn, the steel slit dam 10. Therefore, in this embodiment, the eaves-shaped vertical tie members 14 provided directly above the vertical downstream pillar 2B in the center can be formed to a length shorter than the eaves-shaped vertical tie members 14 provided directly above the inclined downstream pillars 2A at both ends (see comparison of Figures 7 and 8). In this way, the overhanging length of the eaves-shaped vertical tie members 14 is appropriately adjusted to rationally and economically prevent falling objects such as overflow gravel from colliding with the downstream pillar 2.

[0028] Therefore, according to the steel slit dam 10 of this Example 2, the configuration is unchanged in that, of the four downstream pillars 2, the two central downstream pillars 2B are arranged vertically, and therefore the same effect as in Example 1 above is achieved (see paragraph

[0024] above). In addition, according to the steel slit dam 10 of the second embodiment, the eaves-shaped vertical tie members 14 that receive boulders and driftwood in the overflowing debris flow to the downstream side are configured to protrude downstream from the downstream pillars 2, so that boulders and driftwood can fall toward the riverbed without coming into contact with the downstream pillars 2. Therefore, there is no concern that the downstream pillars 2 will be deformed or damaged by violent collisions with debris, driftwood, etc. As a result, the structural slit dam 10 of the present invention has a sufficiently longer service life than the first embodiment, and can contribute to the protection of the valley and riverbed, or prevent damage to residents and others due to the flooding of debris flows in the downstream area. EXAMPLES

[0029] Next, a steel slit dam 10 according to a third embodiment will be described with reference to Figures 9 to 12. Note that the same members as those in the first and second embodiments are given the same reference numerals and the description thereof will be omitted as appropriate. The steel slit dam 10 of this Example 3 differs from the above-mentioned Example 2 mainly in that the length of the eave-shaped vertical connecting members 14 of Example 2 is aligned to the longer length.

[0030] Therefore, according to the steel slit dam 10 of this Example 3, the configuration is unchanged in that, of the four downstream pillars 2, the two central downstream pillars 2B are arranged vertically, and therefore the same effect as in Example 1 above is achieved (see paragraph

[0024] above). Furthermore, since the configuration remains the same in which the eaves-shaped vertical connecting members 14, which channel boulders, driftwood, and the like in the overflowing debris flow downstream, protrude further downstream than the downstream pillar members 2, it achieves the same effect as in the above-mentioned Example 2 (see the second paragraph of paragraph

[0028] above). Furthermore, in the steel slit dam 10 according to the third embodiment, the lengths of all the eaves-shaped vertical ties 14 are aligned to cover the entire downstream pillar 2A in an inclined position, so that even if boulders or driftwood in the debris flow irregularly flow diagonally from the upstream to the downstream as viewed from a plan view, they can pass between the eaves-shaped vertical ties 14 and fall toward the riverbed without worrying about coming into contact with the downstream pillar 2A. Thus, a steel slit dam 10 with superior safety to the steel slit dam 10 according to the second embodiment can be realized. EXAMPLES

[0031] Next, a steel slit dam 10 according to a fourth embodiment will be described with reference to Figures 13 and 14. Note that the same members as those in the first and second embodiments are given the same reference numerals and the description thereof will be omitted as appropriate. The steel slit dam 10 according to this Example 4 is different from the above Example 2 in that the number of upstream pillars 1 and downstream pillars 2 is reduced from four to three, and accordingly, the number of vertical downstream pillars 2B in the center is reduced from two to one. The right side view is the same as that of Example 2 (see Figs. 7 and 8).

[0032] Therefore, according to the steel slit dam 10 of this Example 4, there is no change in the configuration in which the downstream column 2 includes a vertical downstream column 2B, and there is no change in the configuration in which the eaves-shaped vertical connecting member 14 protrudes downstream further than the downstream column 2, so that the same effect as in Example 2 above is achieved (see paragraph

[0028] above). EXAMPLES

[0033] Next, a steel slit dam 10 according to a fifth embodiment will be described with reference to Figures 15 and 16. Note that the same members as those in the first and second embodiments are given the same reference numerals and the description thereof will be omitted as appropriate. The steel slit dam 10 according to this embodiment 5 is different from the embodiment 2 in that the number of upstream pillars 1 and downstream pillars 2 is increased from four to five. Accordingly, one downstream pillar 2A is added in the center in an inclined posture, and the downstream pillars 2A in an inclined posture and the downstream pillars 2B in a vertical posture are arranged alternately. The right side view is the same as that of the embodiment 2 (see Figs. 7 and 8).

[0034] Therefore, according to the steel slit dam 10 of Example 5, there is no change in the configuration in which the downstream column 2 includes a vertical downstream column 2B, and there is no change in the configuration in which the eaves-shaped vertical connecting member 14 protrudes downstream further than the downstream column 2, so that the same effect as in Example 2 above is achieved (see paragraph

[0028] above). EXAMPLES

[0035] Next, a steel slit dam 10 according to a sixth embodiment will be described with reference to Figures 17 and 18. Note that the same members as those in the first and second embodiments are given the same reference numerals and the description thereof will be omitted as appropriate. The steel slit dam 10 according to this Example 6 is different from the above Example 2 in that the number of upstream pillars 1 and downstream pillars 2 is increased from four to seven. Accordingly, the number of downstream pillars 2A in an inclined position is increased from two to three, and the number of downstream pillars 2B in a vertical position is increased from two to four. The right side view is the same as that of Example 2 (see Figs. 7 and 8). However, the steel slit dam 10 of this Example 6 is similar to the steel slit dam 10 of the above-mentioned Example 2 in that two downstream pillars 2B in a vertical position are arranged between two downstream pillars 2A in an inclined position.

[0036] Therefore, according to the steel slit dam 10 of Example 6, there is no change in the configuration in which the downstream column 2 includes a vertical downstream column 2B, and there is no change in the configuration in which the eaves-shaped vertical connecting member 14 protrudes downstream further than the downstream column 2, so that the same effect as in Example 2 above is achieved (see paragraph

[0028] above). EXAMPLES

[0037] Next, a steel slit dam 10 according to a seventh embodiment will be described with reference to Figures 19 and 20. Note that the same members as those in the first and second embodiments are given the same reference numerals and the description thereof will be omitted as appropriate. The steel slit dam 10 of Example 7 differs from Example 3 above in that the eaves-shaped vertical connecting member 14 is provided with a fall prevention member (branch steel pipe) 6 extending horizontally to an adjacent eaves-shaped vertical connecting member 14.

[0038] The fall prevention members (branch steel pipes) 6 are arranged in cases where it is expected that small to medium-sized soil, stones, and driftwood that are smaller than the installation interval of adjacent eaves-shaped vertical tie members 14 will overflow. The fall prevention members 6 allow the small to medium-sized soil, stones, and driftwood to flow away and fall toward the riverbed without coming into contact with (colliding with) the downstream side pillars 2. In this embodiment, the fall prevention members 6 are provided in multiple pieces (12 in total, in this embodiment, three sets of three opposing fall prevention members 6 each, with two of the four eaves-shaped vertical connecting members 14) between the two outermost vertical connecting members 14 and located downstream of the head of the downstream column member 2. In this embodiment, the fall prevention members 6 have a smaller diameter than the eaves-shaped vertical connecting material 14 (or the same diameter as the eaves-shaped vertical connecting material 14), and opposing fall prevention members 6 are not connected to each other, with a predetermined space provided between the ends of opposing fall prevention members 6. The arrangement intervals and the number of fall prevention members 6 can be appropriately changed according to the structural design. For example, it is of course possible to provide similar arrangements between the eaves-shaped vertical tie members 14 located directly above the vertical downstream pillars 2B, which were not provided in this embodiment. Even if small to medium-sized soil and stones (pebbles) or driftwood flow down the riverbed in an irregular manner from the upstream side to the downstream side in a diagonal direction as viewed from the planar direction, they can pass through the gaps between the eaves-shaped vertical tie members 14 located directly above the vertical downstream pillars 2B and fall toward the riverbed without the risk of contacting the downstream pillars 2A. However, when it is not necessary to excessively prevent small and medium-sized earth and rocks, driftwood, and the like from falling, the fall prevention members 6 may not be provided as in the third embodiment.

[0039] Therefore, according to the steel slit dam 10 of Example 7, there is no change in the configuration including the downstream column 2B that is perpendicular to the downstream column 2, and there is no change in the configuration in which the eaves-shaped vertical connecting members 14 protrude downstream further than the downstream column 2.Furthermore, the lengths of all the eaves-shaped vertical connecting members 14 are aligned to the length of the eaves-shaped vertical connecting members 14 that covers the entire downstream column 2A in an inclined position, so that the same effect as in Example 3 above is achieved (see paragraph

[0030] above). In addition, according to the steel slit dam 10 of this embodiment 7, in the event that small to medium-sized soil, stones, and driftwood, etc. that are smaller than the installation spacing of adjacent eave-shaped vertical connecting members 14 are expected to overflow, the small to medium-sized soil, stones, and driftwood, etc. can be effectively diverted and allowed to fall toward the riverbed without coming into contact (colliding) with the downstream pillar material 2, thereby realizing a structure that can minimize deformation and damage to the downstream pillar material 2. EXAMPLES

[0040] Next, a steel slit dam 10 according to an eighth embodiment will be described with reference to Figures 21 and 22. Note that the same members as those in the first and second embodiments are given the same reference numerals and the description thereof will be omitted as appropriate. The steel slit dam 10 according to Example 8 is different from Example 3 in that the downstream columns 2A in an inclined position are rigidly connected to each other substantially horizontally with a long reinforcing member 7, and the downstream columns 2B in a vertical position are rigidly connected to each other substantially horizontally with a short reinforcing member 7, thereby increasing the strength and rigidity of the steel slit dam 10 as a structure. The reinforcing member 7 in this example is a steel pipe of substantially the same diameter as the downstream columns 2.

[0041] Therefore, according to the steel slit dam 10 of Example 8, there is no change in the configuration including the downstream column 2B that is perpendicular to the downstream column 2, and there is no change in the configuration in which the eaves-shaped vertical tie members 14 protrude downstream further than the downstream column 2.Furthermore, the lengths of all the eaves-shaped vertical tie members 14 are aligned to the length of the eaves-shaped vertical tie members 14 that covers the entire downstream column 2A in an inclined position, so that the same effect as in Example 3 above is achieved (see paragraph

[0030] above). In addition, according to the steel slit dam 10 of Example 8, the reinforcing member 7 makes it possible to realize a steel slit dam 10 with increased strength and rigidity, and therefore, compared to Example 3 above, the service life is maintained sufficiently longer, contributing to the protection of the valley and riverbed, and preventing damage to residents and others due to flooding by debris flow in downstream areas.

[0042] Although an embodiment of the present invention has been described above with reference to the drawings, it should be noted that the present invention is not limited to the illustrated examples, and includes the range of design modifications and application variations that would normally be made by a person skilled in the art, provided that the scope does not deviate from the technical concept of the present invention. For example, in the illustrated example, the height of the downstream pillar 2 is made lower than the height of the upstream pillar 1, but this is not limited to this, and the top ends (heights) of the upstream pillar 1 and the downstream pillar 2 can also be made the same. [Explanation of symbols]

[0043] 1 Upstream pillar 2 Downstream pillar 2A Downstream pillar in an inclined position 2B Downstream column in vertical position 3 Horizontal joints 30 branch steel pipe 4 Vertical tie 4H Vertical tie material installed on the top row 5 Support material 6 Fall prevention parts (branch steel pipes) 7 Reinforcement members 10. Steel Slit Dam 14 Eaves-shaped vertical tie 20 Basics

Claims

1. In a steel slit dam constructed three-dimensionally by connecting the upstream pillars and the downstream pillars with horizontal and vertical ties, A steel slit dam, characterized in that at least the downstream pillars installed at both ends of the river in the direction of the river width are installed at a downward angle from the upstream side to the downstream side, and the other downstream pillars are installed vertically.

2. A steel slit dam as described in claim 1, characterized in that the upper end position of the downstream pillar material is set lower than the upper end position of the upstream pillar material, and the vertical connecting material provided at the topmost stage is provided at a downward incline from the upstream side to the downstream side.

3. A steel slit dam as described in claim 1, characterized in that the vertical connecting member provided at the top stage is an eave-shaped vertical connecting member having one end joined to the upper end of the upstream pillar member and the other end configured to protrude downstream in an eave-like manner beyond the downstream pillar member and be supported by the downstream pillar member.

4. A steel slit dam as described in claim 3, characterized in that the eave-shaped vertical connecting member is set to a length that covers at least half of the downstream pillar member located directly below it when viewed from a planar direction.

5. A steel slit dam as described in claim 3 or 4, characterized in that the eave-shaped vertical tie members are provided with fall prevention members extending to adjacent eave-shaped vertical tie members.

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