Method for constructing a dam and dam

Abstract

To provide a dam construction method capable of functioning as a capturing body even during construction and increasing the volume by connecting a new capturing body.SOLUTION: A method of constructing a new dam on an existing dam (100) includes: a step of constructing a pair of non-overflow portions (1a) above the existing dam; and a step of constructing a capturing body (3A) in an opening (2) formed between a pair of non-overflow portions, which allows flowing water flowing from upstream of a river to pass through and captures objects included in the flowing water. In the step of building the capturing body, the capturing body is attached to the non-overflow portion.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for constructing a dam and to a dam. [Background technology]

[0002] A well-known example of a river debris flow countermeasure is a dam (sabo dam) equipped with a trapping body to capture rocks, driftwood, etc. that flow from upstream. A dam has a pair of non-overflow sections that protrude from both sides of the river, with an opening between the non-overflow sections to allow water to pass through. The trap is installed in the opening and traps large-diameter rocks, driftwood, etc. while allowing small-diameter sediment and water to pass through. The trap has an upstream unit facing upstream in the direction of river flow and a downstream unit facing downstream, with both units extending at an angle so that they approach each other as they extend upward and are connected to each other near their upper ends. The trap is installed across the width of the opening and is attached to a concrete foundation at its lower end (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2017-101502 Summary of the Invention [Problem to be solved by the invention]

[0004] Meanwhile, in large rivers or rivers where large debris flows are predicted, dams called high dams, which are 15m or more in height from the bottom of the concrete foundation to the top, are often constructed. In the case of high dams, both the non-overflow section and the trapping body must be high, so construction can take a long time. In this case, if a debris flow occurs during construction, the trapping body will not function as a trapping body when it is not completed, and will not be able to capture rocks, driftwood, etc. Furthermore, if an existing dam becomes filled with sediment or if there are changes to the design standards for the dam, it will be necessary to build a new dam on top of the existing dam and raise the dam level.In this case, raising the dam level is difficult because the structure of the above-mentioned trapping body does not anticipate the addition of a new trapping body.

[0005] Therefore, the present invention has been made in consideration of the above-mentioned problems, and aims to provide a technology that can function as a capture body even during construction, and can connect new capture bodies to raise the height. [Means for solving the problem]

[0006] One aspect of the present invention is a method for constructing a new dam on an existing dam, comprising the steps of constructing a pair of non-overflow sections above the existing dam, and constructing a capture body in an opening formed between the pair of non-overflow sections to allow flowing water from upstream of the river to pass through and capture objects contained in the flowing water, wherein the step of constructing the capture body includes attaching the capture body to the non-overflow sections.

[0007] The capture body further comprises an upstream unit that is provided on the upstream side of the river and captures the object, a downstream unit that is provided on the downstream side of the river and is curved so that its central portion protrudes toward the upstream unit, and a connecting portion that connects the upstream unit and the downstream unit, and in the process of constructing the capture body, it is preferable to attach at least each end of the downstream unit to the non-overflow portion.

[0008] Furthermore, it is preferable that the existing dam is a permeable dam equipped with a pair of non-overflow sections and a capture body, and that the construction includes a first step of connecting the vertical and horizontal members that constitute the new capture body to the existing capture body, a second step of connecting a frame connected to the end of the horizontal member to the upper end of the existing non-overflow section, a third step of connecting the end of the horizontal member to the frame, and a fourth step of pouring concrete into the upper end of the non-overflow section to bury the frame.

[0009] It is also preferable that the second step is carried out immediately before the construction of the cross member in the first step is completed.

[0010] It is also preferable that the fourth step is carried out after the first to third steps are repeated multiple times.

[0011] The fourth step is preferably carried out in a state where the connection portion between the end of the cross member and the frame connected in the third step is exposed.

[0012] One aspect of the present invention is a dam comprising a pair of non-overflow sections and a capture body that is provided in an opening formed between the pair of non-overflow sections and that allows flowing water from upstream of the river to pass through and captures objects contained in the flowing water, and is characterized by comprising a base that is provided in the non-overflow section and to which the capture body is connected, a first connecting portion that is provided on the capture body and connects it to a new capture body, and a second connecting portion that is provided on the base and connects it to the new base.

[0013] It is also preferable that the capture body comprises a horizontal member connected to the mount and a vertical member intersecting the horizontal member, and that the first connecting portion is provided at the upper end of the vertical member.

[0014] Moreover, it is preferable that the frame is buried in the non-overflow portion with the second connecting portion exposed. [Effects of the Invention]

[0015] According to the present invention, the trapping body can be made to function even during construction, and new trapping bodies can be connected to increase the height. [Brief explanation of the drawings]

[0016] [Figure 1] This is an oblique view of the dam before it is raised. [Figure 2] This is an oblique view of a dam with the inside of the non-overflow section visible. [Figure 3]FIG. 1 is a diagram illustrating a method for constructing a dam. [Figure 4] FIG. 1 is a diagram illustrating a method for constructing a dam. [Figure 5] FIG. 1 is a diagram illustrating a method for constructing a dam. [Figure 6] FIG. 1 is a diagram illustrating a method for constructing a dam. [Figure 7] FIG. 1 is a diagram illustrating a method for constructing a dam. [Figure 8] This is an oblique view of the dam after it has been raised. [Figure 9] FIG. 10 is a perspective view of a dam before being raised in a modified example. [Figure 10] FIG. 10 is a perspective view of a dam in a modified example, showing the inside of a non-overflow section. [Figure 11] FIG. 10 is a perspective view of a dam after being raised in a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0017] Preferred embodiments of the present invention will now be described with reference to the drawings.

[0018] <Dam configuration> As shown in Figures 1 and 2, dam 100 is generally called a permeable dam, and comprises a pair of non-overflow sections 1, an opening 2, a capture body 3, and a mounting base 4. In the following, the vertical direction refers to the height direction of dam 100 (depth direction of the river), and the horizontal direction refers to the width direction of dam 100 (width direction of the river) which is perpendicular to the height direction of dam 100.

[0019] The non-overflow sections 1 are walls made of concrete, for example, and are also called sleeves. The pair of non-overflow sections 1 extend from both banks of the river toward the center of the river, crossing the river. A predetermined gap is left between the pair of non-overflow sections 1, and an opening 2 is formed therein. The non-overflow sections 1 are constructed by pouring concrete upward onto a foundation 11 formed on the riverbed.

[0020] The opening 2 is a space formed between a pair of non-overflow sections 1, and a capture body 3 is installed therein. This allows large rocks and driftwood contained in the debris flow to be captured by the capture body 3, while allowing water, sand, small pebbles, etc. to pass through. A foundation 21 is formed at the bottom of the opening 2. The foundation 21 is formed on the riverbed and is made of, for example, concrete.

[0021] The trapping body 3 allows water flowing from upstream of the river to pass through while trapping objects such as large rocks and driftwood. At the opening 2, it is attached to the base 21 of the opening 2 and to the sides of the non-overflow sections 1 on both sides of the river flow direction (both sides in the direction crossing the river). The trapping body 3 is used, for example, in high dams. Here, a "high dam" refers to a dam whose height (dam height) from the riverbed (bottom) of the river on which the dam foundation is installed to the top of the trapping body 3 is 15 m or more. High dams are mainly built on large rivers and rivers where large debris flows are predicted.

[0022] The capture body 3 includes an upstream unit 6, a downstream unit 7, and a connecting portion 8. The upstream unit 6 is installed on the upstream side of the river and is a functional component that captures objects such as rocks and driftwood contained in the debris flow that has flowed down from the upstream side of the dam 100. In other words, the upstream unit 6 is the unit that is directly subjected to the impact of the debris flow.

[0023] When the dam 100 is viewed from above, the upstream unit 6 is provided linearly along the direction across the river (the width direction of the dam 100). The upstream unit 6 includes a plurality of horizontal members 61 and a plurality of vertical members 62 .

[0024] The multiple horizontal members 61 are provided in a direction that crosses the river, and are arranged side by side along the height direction of the dam 100. The spacing between adjacent horizontal members 61 is preferably set smaller than the diameter of the rocks to be captured in the event of a debris flow. The spacing between adjacent horizontal members 61 may be the same from the top to the bottom of the capture body 3, or may be narrowed only above the capture body 3, and can be freely changed depending on the expected scale of the debris flow. The cross member 61 is made up of, for example, a plurality of cylindrical steel pipes, which are connected to each other via flanges provided at each end. Note that the steel pipes may be connected by welding their ends together without providing flanges, but considering the need for replacement after a debris flow collision, it is preferable to use flanges for connection. Each horizontal member 61 is provided so as to penetrate the vertical members 62 and is joined to the vertical members 62 at their intersections. That is, of the multiple steel pipes constituting each horizontal member 61, the steel pipes that intersect with the vertical members 62 are joined to the steel pipes constituting the vertical members 62 and are configured as an integrated cross pipe 3a that is roughly cross-shaped when viewed from the front. Each cross member 61 has its longitudinal ends attached to the opposing side walls of the non-overflow section 1. Specifically, as shown in Figure 2, the ends of each cross member 61 are connected to the frame 4, and the frame 4 is buried in the non-overflow section 1, thereby fixing each cross member 61 to the non-overflow section 1.

[0025] The multiple vertical members 62 are arranged along the height direction of the dam 100, connecting adjacent horizontal members 61 in the height direction. The multiple vertical members 62 are arranged side by side along the height direction of the dam 100. The spacing between adjacent vertical members 62 is preferably set smaller than the diameter of the rocks to be captured in the event of a debris flow. The spacing between adjacent vertical members 62 may be the same from one end to the other in the width direction of the capture body 3, or may be freely changed depending on the expected scale of the debris flow, such as by narrowing the spacing only near the center of the width direction of the capture body 3. The vertical members 62 are made up of, for example, a plurality of cylindrical steel pipes, each end of which is connected to another via a flange. Note that the steel pipes may be connected by welding their ends together without providing flanges, but considering the need for replacement after a debris flow collision, it is preferable to use flanges for connection. Each vertical member 62 is provided so as to penetrate the horizontal member 61 and is joined to the horizontal member 61 at the intersection. That is, of the multiple steel pipes constituting each vertical member 62, the steel pipes that intersect with the horizontal member 61 are joined to the steel pipes constituting the horizontal member 61 and are configured as an integrated cross pipe 3a that is roughly cross-shaped when viewed from the front. The lower end of the vertical member 62 is buried in the foundation 21, so that the lower end of the vertical member 62 stands upright on the foundation 21. A flange portion 91 is provided at the upper end of the vertical member 62. This flange portion 91 functions as a first connecting portion that connects a new capture body above the existing capture body 3 when raising the height of the existing dam 100.

[0026] The downstream unit 7 is located downstream of the river when viewed from the upstream unit 6, and the impact load of the debris flow acting on the upstream unit 6 is transmitted via the connecting part 8, supporting the capture body 3. When the dam 100 is viewed from above, the downstream unit 7 is arranged in a direction that crosses the river, and is curved so that its central portion in the extension direction protrudes toward the upstream unit 6. In other words, the downstream unit 7 employs an arch structure, and is a structural member that uses compressive force to support the impact load of the debris flow transmitted from the upstream unit 6 via the connecting portion 8. The downstream unit 7 includes a plurality of horizontal members 71 and a plurality of vertical members 72 .

[0027] The multiple cross members 71 are arranged in a direction that crosses the river, and are lined up along the height direction of the dam 100. The spacing between adjacent cross members 71 is preferably set smaller than the diameter of the rocks to be captured in the event of a debris flow. The spacing between adjacent cross members 71 may be the same from the top to the bottom of the capture body 3, or may be freely changed depending on the expected scale of the debris flow, such as by narrowing the spacing only above the capture body 3. The cross members 71 are arranged in a position facing the cross member 61 of the upstream unit 6 in the direction of the river flow. The horizontal members 71 are made up of, for example, a plurality of cylindrical steel pipes, which are connected to each other via flanges provided at each end. Since each horizontal member 71 is required to be able 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 pipes that make up the horizontal members 61 of the upstream unit 6. Note that the steel pipes may be connected by welding their ends together without providing flanges, but considering the need for replacement after a debris flow collision, connecting them using flanges is preferable. Each horizontal member 71 is provided so as to penetrate the vertical members 72 and is joined to the vertical members 72 at their intersections. That is, of the multiple steel pipes constituting each horizontal member 71, the steel pipes that intersect with the vertical members 72 are joined to the steel pipes constituting the vertical members 72 to form an integrated crossing pipe 3c that is roughly cross-shaped in front view. Furthermore, the steel pipes may be steel pipes that extend linearly along the axial direction, or steel pipes that are curved along the axial direction, and an appropriate steel pipe may be selected depending on the curvature of the horizontal member 71.

[0028] Each cross member 71 is curved so that its central portion in the longitudinal direction (axial direction) protrudes toward the upstream unit 6. That is, the steel pipes located closer to the longitudinal center of the cross member 71 are closer to the cross member 61 of the upstream unit 6, and the steel pipes located closer to the end of the cross member 71 are farther away from the cross member 61 of the upstream unit 6. By connecting the steel pipes together in this arrangement, the cross member 71 can be formed into an arch shape. Each cross member 71 has its longitudinal ends attached to the opposing side walls of the non-overflow section 1. Specifically, as shown in Figure 2, the ends of each cross member 71 are connected to the frame 4, and the frame 4 is buried in the non-overflow section 1, thereby fixing each cross member 71 to the non-overflow section 1.

[0029] The multiple vertical members 72 are arranged along the height direction of the dam 100, connecting adjacent horizontal members 71 in the height direction. The multiple vertical members 72 are arranged side by side along the height direction of the dam 100. The spacing between adjacent vertical members 72 is preferably set smaller than the diameter of the rocks to be captured in the event of a debris flow. The spacing between adjacent vertical members 72 may be the same from one end to the other in the width direction of the capture body 3, or may be freely changed depending on the expected scale of the debris flow, such as by narrowing the spacing only near the center of the width direction of the capture body 3. The vertical members 72 are made up of, for example, a plurality of cylindrical steel pipes, each end of which is connected to another via a flange. Note that the steel pipes may be connected by welding their ends together without providing flanges, but considering the need for replacement after a debris flow collision, it is preferable to use flanges for connection. Each vertical member 72 is provided so as to penetrate the horizontal member 71 and is joined to the horizontal member 71 at the intersection. That is, of the multiple steel pipes constituting each vertical member 72, the steel pipes that intersect with the horizontal member 71 are joined to the steel pipes constituting the horizontal member 71 and are configured as an integrated cross pipe 3c that is generally cross-shaped when viewed from the front. The lower end of the vertical member 72 is buried in the foundation 21, so that the lower end of the vertical member 72 stands upright on the foundation 21. A flange portion 91 is provided at the upper end of the vertical member 72. This flange portion 91 functions as a first connecting portion that connects a new capture body above the existing capture body 3 when raising the height of the existing dam 100.

[0030] The connecting portion 8 connects the upstream unit 6 and the downstream unit 7 together. The connecting portions 8 are arranged along the direction of river flow, connecting the opposing cross members 61 of the upstream unit 6 and the cross member 71 of the downstream unit 7. That is, like the cross members 61 and 71, the connecting portions 8 are arranged side by side along the height direction of the dam 100. Therefore, the spacing between adjacent connecting portions 8 is set to be smaller than the diameter of the rocks to be captured in the event of a debris flow. Furthermore, like the cross members 61 and 71, the spacing between adjacent connecting portions 8 may be the same from the top to the bottom of the capture body 3, or may be narrowed only above the capture body 3, and can be freely changed depending on the expected scale of the debris flow. The connecting portion 8 is formed, for example, by a cylindrical steel pipe. One end of the steel pipe is connected to a cross member 61 (cross pipe 3a) of the upstream unit 6 via a flange, and the other end is connected to a cross member 71 (cross pipe 3c) of the downstream unit 7 via a flange. Therefore, the cross members 61, 71 to which the connecting portion 8 is connected must be provided with flanges in advance at positions facing each end of the connecting portion 8. Note that the connecting portion 8 is not necessarily connected using flanges, and the connecting portion 8 may be joined to the cross members 61, 71 by welding or the like.

[0031] The frame 4 is erected on the foundation 11 of the non-overflow section 1. The frame 4 is connected to the capture body 3, and when the dam 100 is completed, it will be buried in the non-overflow section 1 while still connected to the capture body 3. The mount 4 is used to firmly fix the capture body 3 to the non-overflow section 1. For each non-overflow section 1, the frame 4 is provided at a position facing the end of the cross member 61 of the upstream unit 6 and at a position facing the end of the cross member 71 of the downstream unit 7. Multiple frames 4 are connected along the height direction of the non-overflow section 1, and are provided at positions where each cross member 61, 71 of the capture body 3 can be connected. The mount 4 includes a plurality of vertical portions 41 and a plurality of horizontal portions 42.

[0032] A plurality of vertical portions 41 are provided along the height direction of the dam 100. The vertical portions 41 are made up of, for example, a plurality of cylindrical steel pipes. Flanges are provided at both ends of the vertical portions 41. The axial ends of each steel pipe are connected to each other via the flanges. The lower ends of the vertical portions 41, which are provided directly in the foundation 11 of the non-overflow portion 1, are buried in the foundation 11, and as a result, the lower ends of the vertical portions 41 are erected on the foundation 11.

[0033] The horizontal portions 42 are provided midway along the axial direction of the vertical portions 41 so as to intersect with the vertical portions 41, and are arranged side by side along the height direction of the dam 100. The horizontal portions 42 are made up of, for example, a plurality of cylindrical steel pipes, and each steel pipe is connected to the horizontal members 61, 71 of the capture body 3 via a flange portion provided at one end of the steel pipe in the axial direction. Each horizontal portion 42 is provided to penetrate the vertical portion 41 and is joined to the vertical portion 41 at the intersection thereof. In other words, the frame 4 is configured as an integrated cross pipe having a generally cross shape when viewed from the front, in which the steel pipes constituting the vertical portions 41 and the steel pipes constituting the horizontal portions 42 are joined together. Each horizontal portion 42 is provided so that one longitudinal end portion is exposed to the opening 2 from the non-overflow portion 1, and is arranged so that this one end portion can be connected to the horizontal members 61, 71. The base 4 is buried in the non-overflow section 1 except for the connection portions with the cross members 61, 71 of the capture body 3 at the horizontal portion 42. By burying the base 4 in the non-overflow section 1, the cross members 61, 71 are fixed to the non-overflow section 1 via the base 4, and the capture body 3 is fixed to the side wall of the non-overflow section 1. The frame 4 extends in the height direction of the non-overflow section 1 by connecting the ends of the vertical sections 41 together. In the dam 100, a flange portion 92 is provided at the upper end of the vertical portion 41 of the frame 4 located at the top. This flange portion 92 is exposed (protrudes) from the upper surface (top end surface) of the non-overflow portion 1. This exposed flange portion 92 functions as a second connecting portion that connects a new frame 4a above the existing frame 4 when the existing dam 100 is raised.

[0034] <How to build a dam> Next, a method for constructing a new dam on the existing dam 100 (a method for raising the height of the dam 100) will be described. When raising the dam 100, a new capture body 3A is constructed at the upper end of the capture body 3 of the existing dam 100, as shown in Fig. 3. When constructing the new capture body 3A, as shown in Fig. 3, the vertical members 62a constituting the upstream unit 6a are connected to the flange portions 91 at the upper ends of the vertical members 62 from near the center of the width of the opening 2 toward the non-overflow portions 1 on both banks, while the horizontal members 61a are connected and assembled (first step). Specifically, the vertical ends of the substantially cross-shaped cross pipes 3a, each having a steel pipe constituting a vertical member 62a and a horizontal member 61a arranged perpendicular to the axial direction of the vertical member 62a, are connected to flanges 91 at the upper ends of the vertical members 62a, while the opposing horizontal ends of adjacent cross pipes 3a are connected to straight pipes (non-cross pipes) 3b extending linearly. As a result, the lower ends of the vertical members 62a constituting the upstream unit 6a are connected to the vertical members 62 of the existing capture body 3, and the lowest horizontal member 61a constituting the upstream unit 6a is connected.

[0035] Similarly to the upstream unit 6a, the downstream unit 7a is assembled by connecting the vertical members 72a constituting the downstream unit 7a to the flange portions 91 at the upper ends of the vertical members 72 from near the center of the width of the opening 2 toward the non-overflow portions 1 on both banks, while connecting the horizontal members 71a, as shown in Figure 3 (first step). Specifically, the vertical ends of the substantially cross-shaped crossing pipes 3c, each having a steel pipe constituting a vertical member 72a and a horizontal member 71a arranged midway through the vertical member 72a so as to be perpendicular to the axial direction of the vertical member 72a, are connected to flange portions 91 at the upper ends of the vertical members 72, while the opposing horizontal ends of adjacent crossing pipes 3c are connected to straight pipes (non-crossing pipes) 3d extending linearly. As a result, the lower ends of the vertical members 72a constituting the downstream unit 7a are connected to the vertical members 72 of the existing capture body 3, and the lowest horizontal member 71a constituting the downstream unit 7a is connected. Furthermore, the cross pipe 3a and the cross pipe 3c are connected by a connecting portion 8a, thereby connecting the lowest stage of the upstream unit 6a and the lowest stage of the downstream unit 7a.

[0036] In the first step, the cross pipes 3a, 3c are connected to the vertical members 62, 72 of the existing capture body 3, while the cross pipes 3a, 3c are connected with the straight pipes 3b, 3d, and when the ends of the horizontal members 61a, 71a respectively come close to the construction area of ​​the non-overflow section 1a, as shown in Fig. 4, the frame 4a is connected to the flange portion 92 at the upper end of the frame 4 exposed on the upper end surface of the existing non-overflow section 1 (second step). In other words, the second step is carried out just before the construction of the horizontal members 61a, 71a in the first step is completed. The mount 4a is a substantially cross-shaped member having a vertical portion 41a and a horizontal portion 42a provided midway along the vertical portion 41a so as to be perpendicular to the axial direction of the vertical portion 41a.

[0037] In the second step, the frame 4a is connected to the flange 92 at the upper end of the frame 4 exposed on the upper end surface of the existing non-overflow section 1, and then the lateral ends of the cross pipes 3a and 3c, which are extended up to a position adjacent to the non-overflow section 1a, are connected to the end of the horizontal section 42a of the frame 4a by the straight pipes 3b and 3d (third step), as shown in Fig. 5. Here, one end of the straight pipes 3b and 3d is connected to the cross pipes 3a and 3c via the flange, and the other end of the straight pipes 3b and 3d is connected to the horizontal section 42a of the frame 4a via the flange. This completes the bottommost part of the new capture body 3A, and the horizontal member 61a at this bottommost part is connected to the mount 4a.

[0038] Next, as shown in Figure 6, steps 1 to 3 are repeated to construct a new trapping body 3A in the second lowest tier. Specifically, the vertical members 62a and 72a of the new crossing tubes 3a and 3c are connected to the upper ends of the vertical members 62a and 72a of the lowermost crossing tubes 3a and 3c, while the adjacent crossing tubes 3a and 3c are connected by the straight tubes 3b and 3d. Furthermore, the crossing tube 3a and the crossing tube 3c are connected by the connecting portion 8a. This connects the upstream unit 6a and the downstream unit 7a. Then, when the ends of the cross members 61a and 71a have come very close to the construction area of ​​the non-overflow section 1a, the new vertical member 41a of the frame 4a is connected to the upper end of the vertical section 41a of the frame 4a. After that, as shown in Fig. 6, the horizontal ends of the cross pipes 3a and 3c, which have been extended to a position adjacent to the non-overflow section 1a, are connected to the horizontal section 42a of the frame 4a by the straight pipes 3b and 3d. One end of the straight pipes 3b and 3d is connected to the cross pipes 3a and 3c via flanges, and the other end of the straight pipes 3b and 3d is connected to the horizontal section 42a of the frame 4a via flanges. This completes the second-lowest section of the new capture body 3A, and the horizontal member 61a in the second-lowest section of capture body 3A is connected to the second-lowest section frame 4a. That is, by connecting the cross pipes 3a and 3c to each other, the vertical members 62a and 72a of the upper and lower sections are arranged coaxially along the height direction of the non-overflow section 1a, and the horizontal members 61a and 71a are arranged with a gap between them in the height direction of the non-overflow section 1a. Furthermore, if the holes in the flanges of the vertical parts 41a of the mounts 4a are formed slightly larger than the outer diameter of the bolts used for connection, the installation errors of the cross pipes 3a and 3c can be easily eliminated by adjusting the positions of the mounts 4a aligned vertically.

[0039] Next, as shown in FIG. 7, concrete is poured onto the upper end surface of the existing non-overflow portion 1 to construct the non-overflow portion 1a (fourth step). In the fourth step, concrete is poured into the upper end surface of the existing non-overflow section 1 so as to bury the connecting portion between the existing base 4 aligned in the height direction of the new capture body 3A and the lowest base 4a of the capture body 3A, and the connecting portion between the lowest base 4a and the second base 4a. Furthermore, the connecting portion between the capture body 3A and the base 4a is not buried, in consideration of replacement during subsequent maintenance of the capture body 3A. In consideration of the connection of the third stage 4a, in the fourth step, concrete is poured so that the flange portion 92 at the upper end (upper end of the vertical portion 41a) of the second stage 4a is exposed. The fourth step may be performed after repeating the first to third steps a number of times. That is, the cross pipes 3a, 3c, the straight pipes 3b, 3d, and the frame 4a may be connected in multiple stages, and then concrete may be poured onto the upper end surface of the existing non-overflow section 1 to construct the non-overflow section 1a.

[0040] Thereafter, the steps of connecting the cross pipes 3a, 3c and straight pipes 3b, 3d to connect the horizontal members 61a, 71a and the vertical members 62a, 72a, connecting the frames 4a, connecting the horizontal members 61a, 71a to the frames 4a, and pouring concrete into the non-overflow section 1a are repeated up to the required height to construct a new capture body 3A and non-overflow section 1a, completing the dam 100 as shown in Figure 8. The cross pipe located at the top has no other cross pipes connected above it, so it is configured in a T-shape when viewed from the front. Through the above steps, a dam 100 as shown in FIG. 8 is constructed.

[0041] According to the above-described construction method for the dam 100 and dam 100A, the trapping bodies 3, 3A are connected to the stands 4, 4a embedded in the concrete that constructs the non-overflow sections 1, 1a, so that the trapping bodies 3, 3A are firmly fixed to the non-overflow sections 1, 1a. This allows some of the debris flow load and impact load acting on the trapping bodies 3, 3A to be released to the non-overflow sections 1, 1a, improving the resistance of the trapping bodies 3, 3A to being pushed out or pulled out. Furthermore, the trapping bodies 3, 3A are simply fixed to the non-overflow sections 1, 1a of the dam 100, 100A at intervals along its height, with the horizontal members 61, 71, 61a, 71a and the vertical members 62, 72, 62a, 72a, each having the same configuration. Therefore, even if the dam is not constructed to the originally planned height, the trapping bodies 3, 3A can function up to the completed height. In other words, conventional trapping bodies lack sufficient strength to function as a dam until they are completed, and therefore cannot function as a dam. In contrast, the above-described dams 100, 100A function as a dam even if a debris flow occurs during construction because the trapping bodies 3, 3A are strong enough to capture rocks, driftwood, and the like. Therefore, even in the construction of a dam, such as a high dam, which requires a long construction period, damage caused by a debris flow during construction can be reduced, and the construction period can be divided.

[0042] Furthermore, if sediment accumulates on the existing dam 100 and it becomes filled with sand, or if there are changes to the dam's design standards, it becomes necessary to construct a new dam on top of the existing dam 100 and raise the height of the dam 100. However, because the structure of conventional traps does not anticipate raising the height, it was not possible to construct a trap with the same structure above an existing trap. However, because the above-mentioned traps 3, 3A are structured to be fixed to the non-overflow sections 1, 1a, it is possible to easily construct the trap 3A above the trap 3 of the existing dam 100. Therefore, if the dam 100 having the above configuration is constructed initially, it is possible to raise the height of the dam 100 by constructing a dam with the same structure above it several years later. This allows the dam 100 to be raised without creating any weak parts in the dam 100A as a whole. In addition, the upper ends of the vertical members 62, 72 of the capture body 3 are provided with flange portions 91 that connect to the vertical members 62a, 72a of the capture body 3A to be newly constructed, and the upper end of the vertical portion 41 of the frame 4 is provided with a flange portion 92 that is exposed from the upper end surface of the non-overflow section 1 and connects to the frame 4a to be newly constructed.Therefore, when raising the existing dam 100 to construct the dam 100A, the new capture body 3A and frame 4a can be easily connected without making any changes to the existing dam 100.

[0043] Furthermore, since the cross members 61, 71, 61a, 71a that make up the capture bodies 3, 3A are attached at both ends to the non-overflow sections 1, 1a, even if rocks or driftwood contained in a debris flow fly over the upper ends of the upstream units 6, 6a and downstream units 7, 7a and fall below the capture bodies 3, 3A, the falling rocks and driftwood are less likely to collide with the capture bodies 3, 3A, thereby preventing damage to the capture bodies 3, 3A. Furthermore, since the stands 4, 4a have a simple structure consisting of vertical sections 41, 41a and horizontal sections 42, 42a, both made from steel pipes, the same materials can be used as the horizontal members 61, 71, 61a, 71a and vertical members 62, 72, 62a, 72a of the capture bodies 3, 3A, making it easy to connect them together.

[0044] Furthermore, during construction of the capture body 3A, the second step of installing the platform 4a is carried out immediately before the construction of the cross members 61a, 71a is completed in the first step. This means that even if an error occurs in the construction position of the cross members 61a, 71a, the error can be eliminated by adjusting the installation position of the platform 4a, and the cross members 61a, 71a can be reliably and easily connected to the platform 4a. In addition, the frame 4a to which the capture body 3A is connected is buried in the concrete poured to construct the non-overflow section 1a, so that the capture body 3A is firmly fixed to the non-overflow section 1a, thereby increasing the rigidity of the dam 100A. Furthermore, after repeating the installation of the vertical members 62a, 72a, horizontal members 61a, 71a and mounting base 4a in steps 1 to 3 over multiple stages, concrete for multiple stages of non-overflow sections 1a can be poured all at once in step 4, thereby increasing the flexibility of construction.

[0045] <Modification> As shown in FIGS. 9 to 11, the above construction method can also be applied to the case where an existing dam 200 is raised to construct a dam 200A. Here, dam 200, 200A differ from dam 100, 100A in the configuration of capture bodies 3B, 3C, so the following will describe capture bodies 3B, 3C in detail. Dam 200 has a pair of non-overflow sections 1, an opening 2, capture bodies 3B, and a base 4. The capture body 3B includes an upstream unit 6B, a downstream unit 7, and a connecting portion 8. The upstream unit 6B is provided on the upstream side of the river and is a functional component that captures objects such as rocks and driftwood contained in the debris flow that has flowed down from the upstream side of the dam 200. In other words, the upstream unit 6B is the unit that is directly subjected to the impact of the debris flow.

[0046] When the dam 200 is viewed from above, the upstream unit 6B is bent so that its central portion in the extension direction protrudes toward the upstream side of the river. In other words, the upstream unit 6B employs a curved arch structure, which reduces the composite stress level of the temperature stress of the upstream unit 6B (internal stress that occurs in a structure due to temperature changes (for example, stress due to expansion and contraction of each component due to changes in outside temperature)). The upstream unit 6B includes a plurality of horizontal members 61 and a plurality of vertical members 62.

[0047] The multiple cross members 61 are arranged in a direction that crosses the river, and are arranged side by side along the height direction of the dam 200. The spacing between adjacent cross members 61 is preferably set smaller than the diameter of the rocks to be captured in the event of a debris flow. The spacing between adjacent cross members 61 may be the same from the top to the bottom of the capture body 3, or may be freely changed depending on the expected scale of the debris flow, such as by narrowing the spacing only above the capture body 3. The cross members 61 are arranged in a position facing the cross member 71 of the downstream unit 7B in the direction of the river flow. The cross member 61 is made up of, for example, a plurality of cylindrical steel pipes, which are connected to each other via flanges provided at each end. Note that the steel pipes may be connected by welding their ends together without providing flanges, but considering the need for replacement after a debris flow collision, it is preferable to use flanges for connection. Each horizontal member 61 is provided so as to penetrate the vertical members 62 and is joined to the vertical members 62 at their intersections. That is, of the multiple steel pipes constituting each horizontal member 61, the steel pipes that intersect with the vertical members 62 are joined to the steel pipes constituting the vertical members 62 to form an integrated crossing pipe 3a that is roughly cross-shaped in front view. Furthermore, the steel pipes may be steel pipes that extend linearly along the axial direction, or steel pipes that are curved along the axial direction, and an appropriate steel pipe may be selected depending on the curvature of the horizontal member 61. Each horizontal member 61 is bent so that the center portion in the longitudinal direction (axial direction) protrudes toward the upstream side of the river. Each horizontal member 61 has a curved arch structure. Each cross member 61 has its longitudinal ends attached to the opposing side walls of the non-overflow section 1. Specifically, as shown in Figure 10, the ends of each cross member 61 are connected to a frame 4, and the frame 4 is buried in the non-overflow section 1, thereby fixing each cross member 61 to the non-overflow section 1.

[0048] The multiple vertical members 62 are arranged along the height direction of the dam 200, connecting adjacent horizontal members 61 in the height direction. The multiple vertical members 62 are arranged side by side along the height direction of the dam 200. The spacing between adjacent vertical members 62 is preferably set smaller than the diameter of the rocks to be captured in the event of a debris flow. The spacing between adjacent vertical members 62 may be the same from one end to the other in the width direction of the capture body 3B, or may be freely changed depending on the expected scale of the debris flow, such as by narrowing the spacing only near the center in the width direction of the capture body 3B. The vertical members 62 are made up of, for example, a plurality of cylindrical steel pipes, each end of which is connected to another via a flange. Note that the steel pipes may be connected by welding their ends together without providing flanges, but considering the need for replacement after a debris flow collision, it is preferable to use flanges for connection. Each vertical member 62 is provided so as to penetrate the horizontal member 61 and is joined to the horizontal member 61 at the intersection. That is, of the multiple steel pipes constituting each vertical member 62, the steel pipes that intersect with the horizontal member 61 are joined to the steel pipes constituting the horizontal member 61 and are configured as an integrated cross pipe 3a that is roughly cross-shaped when viewed from the front. The lower end of the vertical member 62 is buried in the foundation 21, so that the lower end of the vertical member 62 stands upright on the foundation 21. A flange portion 91 is provided at the upper end of the vertical member 62. This flange portion 91 functions as a first connecting portion that connects a new capture body above the existing capture body 3 when raising the height of the existing dam 200.

[0049] The downstream unit 7 is provided downstream of the river as viewed from the upstream unit 6B, and the impact load of the debris flow acting on the upstream unit 6B is transmitted via the connecting portion 8 to support the capture body 3B. When the dam 200 is viewed from above, the downstream unit 7 is provided in a direction that crosses the river, and is curved so that its central portion in the extension direction protrudes toward the upstream unit 6B. In other words, the downstream unit 7 employs an arch structure, and is a structural member that uses compressive force to support the impact load of the debris flow transmitted from the upstream unit 6B via the connecting portion 8. The downstream unit 7 includes a plurality of horizontal members 71 and a plurality of vertical members 72 . The downstream unit 7 has the same configuration as that of the above embodiment, and therefore the same reference numerals are used and the description thereof will be omitted.

[0050] The connecting portion 8 connects the upstream unit 6B and the downstream unit 7 together. The connecting portion 8 is provided along the direction of the river flow, and connects the horizontal member 61 of the upstream unit 6B and the horizontal member 71 of the downstream unit 7, which face each other. The configuration of the connecting portion 8 is the same as that of the above embodiment, and therefore a description thereof will be omitted.

[0051] The platform 4 is erected on the foundation 11 of the non-overflow section 1. The platform 4 is connected to the capture body 3B, and when the dam 200 is completed, it will be buried in the non-overflow section 1 while still connected to the capture body 3B. The mount 4 is used to firmly fix the capture body 3B to the non-overflow section 1. For each non-overflow section 1, the frame 4 is provided at a position facing the end of the cross member 61 of the upstream unit 6B and at a position facing the end of the cross member 71 of the downstream unit 7. Multiple frames 4 are connected along the height direction of the non-overflow section 1, and are provided at positions where each cross member 61, 71 of the capture body 3B can be connected. The configuration of the pedestal 4 is the same as that of the above embodiment, so the same reference numerals are used and the description will be omitted.

[0052] The connected horizontal members 61, 71 are bent and formed into an arch shape so that the center portion in their extension direction (axial direction of the horizontal members 61, 71) protrudes most toward the upstream side of the river. When viewed in plan, the horizontal members 61, 71 are arranged so that the horizontal members 61 and 71 facing each other in the river flow direction are spaced approximately equally apart from one end to the other. In other words, the horizontal members 61 and 71 facing each other in the river flow direction are connected by multiple connecting portions 8 of the same length. Each vertical member 62 connects each horizontal member 61 to another, and each vertical member 72 connects each horizontal member 71 to another.

[0053] The method of constructing dam 200A by raising the height of dam 200 involves constructing a new capture body 3C on the upper end of capture body 3B of existing dam 200, thereby constructing non-overflow section 1. The specific procedure is the same as the method of constructing dam 100A by raising the height of dam 100 in the above embodiment.

[0054] 9 to 11, in addition to achieving the same effects as the construction method of the dam 100 and dam 100A in the above embodiment, the upstream unit 6B is formed to be bent, so that the composite stress intensity due to temperature stress can be reduced even when both ends are fixed to the non-overflow section 1 via the mounting frame 4. This makes it possible to reduce the composite stress intensity due to temperature stress while increasing the strength of the dams 200, 200A, and also makes it possible to reduce the steel pipe diameter of the upstream unit 6B.

[0055] <Other> Although the preferred embodiments of the present invention have been described, the present invention is not limited to the above embodiments and includes all aspects encompassed within the concept and scope of the claims. Furthermore, each configuration may be appropriately and selectively combined 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 modified depending on the specific usage of the present invention.

[0056] For example, the trapping bodies 3, 3A are not limited to trapping bodies 3, 3A in which upstream units 6, 6a and downstream units 7, 7a are connected by connecting parts 8, 8a, but may simply be trapping bodies in which vertical members and horizontal members are assembled in a lattice pattern, and the above-mentioned dam construction method is also applicable to dams equipped with trapping bodies of such simple structures. In other words, the above-mentioned dam construction method is applicable to any trapping body equipped with horizontal members extending in a direction intersecting the plane direction of the side surface (the surface facing the opening 2) of the non-overflow section 1, 1a. Furthermore, it is not necessary to fix the lower ends of the vertical members 62, 72, 62a, 72a of the capture bodies 3, 3A to the base 21 of the opening 2, and it is important that the horizontal members 61, 71, 61a, 71a are arranged in multiple stages in the height direction in the non-overflow section 1. Furthermore, in the capture body 3, 3A, only the cross members 61, 71, 61a, 71a of the downstream unit 7, 7a may be attached to the non-overflow portion 1, 1a. Furthermore, if the amount of elevation of the dam 100 is small, in the fourth step, concrete is poured up to a height that buries the upper end of the frame 4a, and the non-overflow section 1a is constructed up to a position higher than the upper end of the capture body 3A, thereby completing the dam 100A. Furthermore, although the example in which the capture bodies 3, 3A are provided on the dams 100, 100A called high dams has been described, they may also be provided on dams that are not high dams. Furthermore, the method of connecting each vertical member 62, 72, 62a, 72a and each horizontal member 61, 71, 61a, 71a is not limited to connection using bolts and nuts via the flange portions, but the steel pipes that make up each vertical member 62, 72, 62a, 72a and each horizontal member 61, 71, 61a, 71a may also be joined together by welding or the like. Furthermore, the crossing pipes constituting each of the vertical members 62, 72, 62a, 72a and each of the horizontal members 61, 71, 61a, 71a are not limited to the crossing pipes 3a, 3c formed in a generally cross shape or a generally T shape in front view, but can be freely changed in shape depending on the configuration of the capture body 3, 3A. The non-crossing pipes are not limited to the straight pipes 3b, 3d, but can be freely changed in shape, such as by being curved, depending on the configuration of the capture body 3, 3A. [Explanation of symbols]

[0057] 1,1a Non-overflow area 11 Basics 2 Opening 21 Basics 3,3A capture object 4,4a Mounting stand 41,41a Vertical section 42,42a Lateral part 6,6a Upstream unit 61,61a Cross member 62,62a Vertical members 7,7a Downstream unit 71,71a Cross member 72,72a Vertical member 8,8a Connecting part 91 Flange 92 Flange 100,100A Dam

Claims

1. A method for constructing a new dam on an existing dam, comprising: constructing a pair of non-overflow sections above the existing dam; and constructing a capture body in an opening formed between the pair of non-overflow sections, which allows flowing water flowing from the upstream of the river to pass through and captures objects contained in the flowing water, In the step of constructing the trap, the trap is attached to the non-overflow portion, The existing dam is a permeable dam equipped with a pair of non-overflow sections and a capture body, A first step of connecting vertical members and horizontal members constituting a new capture body to an existing capture body; a second step of connecting a frame connected to the end of the cross member to an upper end of the existing non-overflow section; a third step of connecting the end of the cross member to the frame; a fourth step of pouring concrete into the upper end of the non-overflow section to bury the frame; A method for constructing a dam, comprising:

2. The trapping body includes an upstream unit provided on the upstream side of the river for trapping the object, a downstream unit provided on the downstream side of the river and curved so that its central portion protrudes toward the upstream unit, and a connecting portion connecting the upstream unit and the downstream unit, 2. The method for constructing a dam according to claim 1, wherein in the step of constructing the capture body, at least each end of the downstream unit is attached to the non-overflow portion.

3. 3. The method for constructing a dam according to claim 1, wherein the second step is carried out immediately before the construction of the cross members in the first step is completed.

4. 4. The method for constructing a dam according to claim 1, wherein the fourth step is carried out after the first to third steps are repeated a plurality of times.

5. A method for constructing a dam described in any one of claims 1 to 4, characterized in that the fourth step is carried out in a state where the connection portion between the end of the cross member and the frame connected in the third step is exposed.

6. A dam comprising a pair of non-overflow sections and a capture body provided at an opening formed between the pair of non-overflow sections, which allows flowing water flowing from upstream of a river to pass through and captures objects contained in the flowing water, a frame provided in the non-overflow section and to which the capture body is connected; a first connecting portion provided on the capture body and configured to connect to a new capture body; a second connecting portion provided on the cradle and configured to connect to a new cradle; The capture body includes a vertical member provided along a height direction, the first connecting portion is a flange portion provided at an upper end portion of the vertical member, The stand includes a vertical portion provided along a height direction, The second connecting portion is provided at the upper end of the vertical portion of the uppermost pedestal and is a flange portion exposed on the upper surface of the non-overflow portion. A dam characterized by:

7. The capture body includes a horizontal member that crosses the vertical member and is connected to the frame. The dam according to claim 6, characterized in that

8. 8. The dam according to claim 6 or 7, wherein the platform has a horizontal portion that intersects with the vertical portion, one end of which is exposed to the opening, and is connected to the capture body.

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