Dam construction method

Abstract

To provide a dam construction method capable of accurately welding members forming a dam such that deviation does not occur upon assembly of each of the members in a welding process and reducing work hours to decrease a construction cost.SOLUTION: A construction method of a dam constituted of a plurality of column parts, for forming the column part, comprises: a flange fastening step of fastening a first flange and a second flange using fastening members; a temporary attachment step of temporarily attaching the first flange with a part of a connection part of a first pipe, and the second flange with a part of a connection part of a second pipe; and a main welding step of welding the first flange with the connection part of the first pipe over a whole circumference of the first pipe as well as the second flange with the connection part of the second pipe over a whole circumference of the second pipe.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a method for constructing dams that are constructed in mountain rivers, valleys, etc., and that capture driftwood, rocks, etc. that are generated during floods, etc., to prevent disasters before they occur. [Background technology]

[0002] Permeable sabo dams, which are installed in rivers across the width of the river, are known as dams constructed in mountain rivers and valleys to protect against debris flows or driftwood that occur during floods. Permeable sabo dams generally extend from both banks of the river toward the center of the river and are composed of non-overflow sections made of concrete or the like, and a trapping body placed between the non-overflow sections extending from both banks. Hereinafter, in this specification, the trapping body used in permeable sabo dams will be referred to as the trapping body of the dam or simply as a dam.

[0003] The dam allows water from upstream to pass through while preventing objects such as driftwood and rocks contained in the debris flow from reaching the downstream area.

[0004] Conventionally, as a configuration of such a dam, a configuration in which a plurality of pillars and beams are combined three-dimensionally, as described in Patent Document 1, has been known. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-328721 Summary of the Invention [Problem to be solved by the invention]

[0006] Generally, as shown in Figure 1, a dam 100 has multiple pillar structures 110 arranged at intervals in the width direction of the river. The pillar structures 110 are composed of a pair of upstream pillar sections 120 and downstream pillar sections 130, and a beam section 140. The upstream pillar section 120 and the downstream pillar section 130 are joined so as to intersect near their tops, and are connected via the beam section 140 at their vertically intermediate sections. Each pillar section 120, 130 is configured to have a predetermined length by connecting multiple first pillar members 1 and second pillar members 2 in the longitudinal direction. Furthermore, the pillar structures 110 arranged at a distance are each connected by multiple girder sections 150.

[0007] In this way, the columns 120, 130, beams 140 and girders 150 used in the dam 100 are connected to each other via a large number of connecting parts.

[0008] In addition, the column sections 120, 130, the beam section 140 and the girder section 150 are composed of pipe sections made of steel pipes and flange sections made of steel plates, and each connecting section has a structure in which the respective flange sections are connected to each other using fastening members such as bolts and nuts.

[0009] The pillars 120, 130, beams 140 and girders 150 used in the dam 100, as well as each connecting section, are required to have a structure with excellent strength so as not to be destroyed when capturing driftwood and rocks contained in a mudslide.

[0010] Conventionally, the columns 120, 130, beams 140, and girders 150 are joined by firmly welding the pipes and flanges together, and these welding operations are performed at each joint between the pipes and flanges.

[0011] For this reason, in the production of the huge dam 100, many pipe sections and flange sections had to be welded together to complete the numerous columns 120, 130, beams 140, and girders 150, which took a lot of time. In addition, because the welds required strength, the pipe sections and flange sections had to be firmly welded together using weaving welding or the like, and it took a lot of time to weld one joint.

[0012] Furthermore, because each pipe section and flange section is welded separately, misalignment of the axis or angle around the axis may occur when the first pillar member 1 and the second pillar member 2 are combined longitudinally. In such cases, each member needs to be corrected, but because the installation site for the dam 100 is in a mountainous region, correction work is limited. For this reason, each member needs to be manufactured with high precision. However, manufacturing while taking into account the dimensional tolerances of the combined members requires a lot of effort, and there was a demand for improved workability.

[0013] Therefore, the present invention has been made in consideration of the above matters, and its objective is to provide a method for manufacturing a dam that can accurately weld the components that make up the dam so that no misalignment occurs when assembling the components during the welding process, and that can shorten the working time and reduce manufacturing costs. [Means for solving the problem]

[0014] The present invention has been made to achieve the above object and has the following features.

[0015] The method for manufacturing a dam according to the present invention is a method for manufacturing a dam having a plurality of pillar portions, wherein the pillar portions are manufactured by the following steps: a flange fastening process for fastening a first flange and a second flange together with fastening members; a temporary attaching process for temporarily attaching a portion of the joint between the first flange and the first pipe and a portion of the joint between the second flange and the second pipe; and a main welding process for welding the joint between the first flange and the first pipe around the entire circumference of the first pipe, and simultaneously welding the joint between the second flange and the second pipe around the entire circumference of the second pipe.

[0016] In the dam manufacturing method of the present invention, it is preferable that in the main welding process, while the first flange and the second flange are fastened, the joint between the first flange and the first pipe and the joint between the second flange and the second pipe are welded.

[0017] In the dam manufacturing method of the present invention, in the main welding process, the connection portion between the first flange and the first pipe and the connection portion between the second flange and the second pipe are welded by a welding device that is movable in the axial direction of the first pipe and the second pipe, and it is preferable that the welding device be placed on a welding machine rail that is laid to extend in the axial direction of the first pipe and the second pipe.

[0018] In the dam manufacturing method of the present invention, it is preferable that the first pipe is supported by a drive roller that is driven to rotate by a drive means, the second pipe is rotatably supported by a driven roller, and the driven roller is movably placed on a rail for a turning roll that is laid to extend in the axial direction of the first pipe and the second pipe.

[0019] In the dam manufacturing method of the present invention, it is preferable that in the main welding process, the joint between the first flange and the first pipe and the joint between the second flange and the second pipe are welded using a welding device equipped with a copying device.

[0020] The above summary of the invention does not list all of the features necessary for the present invention, and subcombinations of these features may also constitute inventions. [Effects of the Invention]

[0021] According to the present invention, the first and second pillar members, which are to be combined in the completed state of the dam, can be welded in a pre-connected state, allowing for accurate welding without misalignment during assembly of the members. Furthermore, the pipe portions and flange portions of the first and second pillar members can be welded simultaneously, shortening the manufacturing time and reducing manufacturing costs. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 1 is a perspective view showing an example of a dam according to an embodiment of the present invention. [Figure 2] FIG. 2 is a perspective view showing a first pillar member and a second pillar member according to the embodiment of the present invention. [Figure 3] 4 is a flowchart showing an example of a manufacturing process for a dam according to an embodiment of the present invention. [Figure 4] FIG. 4 is a perspective view illustrating a flange fastening step according to an embodiment of the present invention. [Figure 5] FIG. 4 is a perspective view illustrating a temporary welding step and a main welding step according to an embodiment of the present invention. [Figure 6] 1 is a schematic diagram of a welding device according to an embodiment of the present invention, viewed from above; DETAILED DESCRIPTION OF THE INVENTION

[0023] Preferred embodiments for carrying out the present invention will be described below with reference to the drawings. Note that the following embodiments do not limit the inventions according to the claims, and not all of the combinations of features described in the embodiments are necessarily essential to the solution of the invention.

[0024] Fig. 1 is a perspective view showing an example of a dam according to an embodiment of the present invention, and Fig. 2 is a perspective view showing a first pillar member and a second pillar member according to an embodiment of the present invention. In this specification, the width direction, upstream direction, and downstream direction of a river are defined as the directions and orientations of the arrows shown in Fig. 1.

[0025] First, the dam 100 manufactured by the dam manufacturing method of the present invention and each member used in the dam 100 will be described.

[0026] The dam 100 manufactured by the dam manufacturing method of the present invention is composed of a plurality of pillar structures 110 arranged at intervals in the width direction of the river, and a plurality of girder sections 150 connecting adjacent pillar structures 110, as shown in Figure 1.

[0027] The pillar structure 110 is composed of a pair of pillars 120 on the upstream side and a pillar 130 on the downstream side, and a beam 140. The pillars 120 on the upstream side and the pillar 130 on the downstream side are joined so as to intersect near their tops, and are connected via the beam 140 near the middle in the vertical direction.

[0028] Each of the pillars 120, 130 is configured to have a predetermined installation height by connecting multiple first pillar members 1 and second pillar members 2 in the longitudinal direction. In addition, the upstream pillar 120 has a connecting part that extends in the width direction of the river and connects to the girder part 150.

[0029] Similar to the pillars 120 and 130, the beam 140 is configured to have a predetermined length by connecting a plurality of first beam members 141 and second beam members 142 in the longitudinal direction.

[0030] The first pillar member 1, the second pillar member 2, the first beam member 141 and the second beam member 142 are each composed of a pipe portion made of a steel pipe and a flange portion made of a steel plate.

[0031] The girder portion 150, like each of the column members 1 and 2 and each of the beam members 141 and 142, is composed of a pipe portion made of a steel pipe and a flange portion made of a steel plate.

[0032] The connection portion A between the first column member 1 and the second column member 2, the connection portion B between the first beam member 141 and the second beam member 142, and the connection portion C between the upstream column portion 120 and the girder portion 150 are connected by fastening members such as bolts and nuts at their respective flange portions.

[0033] In this way, the dam 100 is constructed by connecting parts of a predetermined length and assembling them three-dimensionally, so each part can be manufactured in a factory and then transported by truck to the installation site. Also, because the parts have a connecting structure and can be disassembled, even if part of the dam 100 is damaged, only the damaged part can be replaced, making it an easy structure to repair.

[0034] As described above, the dam 100 comprises pillars 120, 130, beams 140, and girder 150, which have common characteristics. Hereinafter, in this specification, the pillars 120, 130, beams 140, and girder 150 will be collectively referred to as pillars 120. Furthermore, one of the pillars 120 connected in the longitudinal direction at each connecting portion will be referred to as a first pillar member 1, and the other will be referred to as a second pillar member 2.

[0035] As shown in Fig. 2, the first pillar member 1 includes a first pipe 1a and a first flange 1b, and the second pillar member 2 includes a second pipe 2a and a second flange 2b.

[0036] The first pipe 1a and the second pipe 2a are, for example, cylindrical members made of general structural carbon steel pipes with an outer diameter of approximately 400 mm to 600 mm. The first pipe 1a and the second pipe 2a are cut to a predetermined length according to the specifications of the completed dam 100. The end faces of the first pipe 1a and the second pipe 2a, which are to be joined with the first flange 1b or the second flange 2b, are grooved to ensure appropriate penetration in the main welding step S4, which will be described later.

[0037] The first flange 1b and the second flange 2b are, for example, disk-shaped members made of general structural rolled steel with a thickness of approximately 25 mm to 50 mm. The first flange 1b and the second flange 2b are cut to a diameter larger than the outer diameter of the first pipe 1a and the second pipe 2a. The edges of the first flange 1b and the second flange 2b are provided with a plurality of bolt holes at positions outside the outer diameter of the first pipe 1a and the second pipe 2a. The bolt holes are spaced apart from one another along the outer diameter of the first flange 1b and the second flange 2b.

[0038] Next, a method for manufacturing such a first pillar member 1 and a second pillar member 2 in this embodiment will be described.

[0039] FIG. 3 is a flowchart showing an example of a manufacturing process for a dam according to an embodiment of the present invention, FIG. 4 is an oblique view for explaining a flange fastening process according to an embodiment of the present invention, and FIG. 5 is an oblique view for explaining a temporary attaching process and a main welding process according to an embodiment of the present invention.

[0040] First, prepare a first pipe 1a and a first flange 1b that are required to form the first pillar member 1. At the same time, prepare a second pipe 2a and a second flange 2b that are required to form the second pillar member 2 that will be connected to the first pillar member 1 when the dam 100 is completed. In this embodiment, this process is referred to as a material preparation process S1.

[0041] Next, as shown in Fig. 4, the first flange 1b and the second flange 2b are fastened together with a plurality of fastening members 3. As an example, the fastening members 3 may be bolts and nuts used in assembling the dam 100, but are not limited to these. Any known fastening members may be used as long as they can fasten the first flange 1b and the second flange 2b together without misalignment and can be removed after the first pillar member 1 and the second pillar member 2 are completed. In this embodiment, this step is referred to as the flange fastening step S2.

[0042] Next, as shown in FIG. 5 , the end face of the first pipe 1a is tack-attached to the outward-facing surface of the first flange 1b, which was connected in the flange fastening step S2, by aligning the end face of the first pipe 1a with an appropriate position. For example, tack welding may be performed at multiple locations along the outer periphery of the first pipe 1a at the joint D between the first pipe 1a and the first flange 1b. Similarly, the end face of the second pipe 2a is tack-attached to the outward-facing surface of the second flange 2b, which was connected in the flange fastening step S2, by aligning the end face of the second pipe 2a with an appropriate position, and the joint E between the second pipe 2a and the second flange 2b is tack-attached. In this embodiment, this step is referred to as the tack-attaching step S3. The tack-attaching step S3 allows subsequent work to be performed while maintaining the relative positions of the first pipe 1a and the first flange 1b, and the second pipe 2a and the second flange 2b.

[0043] Next, the entire circumferences of the first pipe 1a and the second pipe 2a are simultaneously welded at joint D between the first pipe 1a and the first flange 1b and joint E between the second pipe 2a and the second flange 2b. In this embodiment, welding is performed by arc welding, for example. It is preferable to deposit many weld beads to increase the strength of the joint. For example, it is preferable to perform welding using a so-called weaving method, in which weld beads are laid while the electrode is moved alternately in directions intersecting the welding direction. In this embodiment, this step is referred to as main welding step S4.

[0044] In this way, the first pillar member 1 and the second pillar member 2, which will be connected when the dam 100 is completed, are manufactured by fastening the first flange 1b and the second flange 2b in advance and welding joints D and E simultaneously, thereby preventing axial misalignment and axial angular misalignment between the first pipe 1a and the second pipe 2a after completion.

[0045] In addition, the time required for welding can be reduced by welding joints D and E at the same time. The effect of reducing the work time is that, including the time required for welding setup, the work can be completed in less than half the time compared to welding each joint one at a time.

[0046] After the main welding process S4, unnecessary spatter is removed, and the fastening members fastening the first flange 1b and the second flange 2b together are removed to separate the first pillar member 1 and the second pillar member 2. The separated first pillar member 1 and second pillar member 2 are subjected to appropriate rust prevention treatment, painting, etc. In this embodiment, this process is referred to as the finishing process S5.

[0047] In this way, the first pillar member 1 and the second pillar member 2 can be separated after the main welding process S4, and can be made to a length suitable for storage in the factory or transportation by truck to the installation site.

[0048] After the finishing step S5, each component is transported to the installation site of the dam 100, where it is properly assembled and completed.

[0049] Next, a suitable welding device for performing the main welding step S4 in this embodiment will be described.

[0050] FIG. 6 is a schematic diagram of the welding device according to this embodiment seen from above, showing a state in which a first pillar member 1 and a second pillar member 2 are placed on the welding device.

[0051] The welding apparatus comprises a fixed turning roll 10, a movable turning roll 20, and a movable torch stand 30 (referred to as the "welding apparatus" in the claims).

[0052] The fixed turning roll 10 supports either the first pillar member 1 or the second pillar member 2, and rotates the first pillar member 1 and the second pillar member 2 around its axis. Note that, although Fig. 6 shows a state in which the first pillar member 1 is supported by the fixed turning roll 10, this is not limiting, and the second pillar member 2 may also be supported by the fixed turning roll 10. Below, a case in which the first pillar member 1 is supported by the fixed turning roll 10 will be described.

[0053] The fixed turning roll 10 includes a driving roller 11 that supports the outer peripheral surface of the first pipe 1a from below at least two points.

[0054] At least one of the drive rollers 11 that support the first pipe 1a at two points receives power from a drive means 12 and rotates around an axis parallel to the axial direction of the first pipe 1a. The drive roller 11 rotates while supporting the outer circumferential surface of the first pipe 1a, causing the first pipe 1a to rotate around its axis.

[0055] The movable turning roll 20 rotatably supports the other of the first pillar member 1 or the second pillar member 2. Although Fig. 6 shows the second pillar member 2 supported by the movable turning roll 20, this is not limiting, and the first pillar member 1 may be supported by the movable turning roll 20. Below, a case where the second pillar member 2 is supported by the movable turning roll 20 will be described.

[0056] The movable turning roll 20 includes driven rollers 21 that support the outer peripheral surface of the second pipe 2a from below at least two points.

[0057] The driven roller 21 rotates about an axis parallel to the axial direction of the second pipe 2a, and supports the second pipe 2a rotatably about that axis. The driven roller 21 is movably placed on a turning roll rail 25 that is laid so as to extend in the axial direction of the second pipe 2a.

[0058] With such a movable turning roll 20, the position of the driven roller 21 can be freely determined along the turning roll rail 25 to match the overall length of the first pillar member 1 and second pillar member 2 to be manufactured, so that the first pillar member 1 and second pillar member 2 can be efficiently installed on the welding equipment.

[0059] Mobile torch stand 30 includes a first torch 31 that welds one of joint D or joint E, and a second torch 32 that welds the other of joint D or joint E. Note that while Fig. 6 shows a case where first torch 31 is positioned to weld joint D, this is not limiting, and first torch 31 may also be positioned to weld joint E. Below, a case where first torch 31 is positioned to weld joint D will be described.

[0060] The first torch 31 welds the joint D of the first pillar member 1 rotated by the fixed turning roll 10 around the entire circumference of the first pipe 1a. The second torch 32 welds the joint E of the second pillar member 2 rotated by the fixed turning roll 10 around the entire circumference of the second pipe 2a.

[0061] The first torch 31 and the second torch 32 can be well-known welding torches, and preferably have a weaving function. Furthermore, the distance between the first torch 31 and the joint D and the distance between the second torch 32 and the joint E are affected by dimensional tolerances such as cylindricity of the first pipe 1a and the second pipe 2a, and may change with rotation around the axis. Therefore, it is preferable to equip the first torch 31 and the second torch 32 with a copying device to keep the distance between the first torch 31 and the joint D and the joint E constant. The copying device used in this embodiment can be a well-known automatic copying device.

[0062] The mobile torch stand 30 is movably placed on a welding machine rail 35 that is laid so as to extend in the axial direction of the first pipe 1a and the second pipe 2a.

[0063] With such a mobile torch stand 30, the positions of the first torch 31 and the second torch 32 can be freely determined along the welding machine rail 35 to match the positions of the joints D and E of the first pillar member 1 and the second pillar member 2 installed on the fixed turning roll 10 and the mobile turning roll 20, thereby allowing efficient preparation for welding work.

[0064] Furthermore, since either the first pillar member 1 or the second pillar member 2 is installed on the fixed turning roll 10, the movable turning roll 20 and the movable torch stand 30 can be smoothly moved to the predetermined position using the fixed turning roll 10 as a reference.

[0065] The dam manufacturing method of this embodiment has been described with reference to the case where the second pillar member 2 is installed on the movable turning roll 20 that is movably mounted on the turning roll rail 25, but if the overall length of the first pipe 1a and the second pipe 2a is short, the second pillar member 2 may be installed on a turning roll that is fixed at a predetermined distance in the axial direction of the fixed turning roll 10 and the second pillar member 2 and is equipped with a driven roller. It is clear from the claims that such modified or improved embodiments are also included within the technical scope of the present invention. [Explanation of symbols]

[0066] 1 First pillar member 1a First Pipe 1b First flange 2 Second pillar member 2a Second Pipe 2b Second flange 3 Fastening members 10 Fixed turning roll 11 Drive roller 12 Driving means 20 Mobile Turning Roll 21 driven roller 25 Turning roll rail 30 Mobile Torch Stand 31 The First Torch 32 The Second Torch 35 Welding machine rail 100 Dam 110 Column structure 120, 130 Column section 140 Beam section 150 digits

Claims

1. A method for manufacturing a dam having a plurality of pillars, comprising the steps of: a flange fastening step of fastening a first flange and a second flange of the column portion by a fastening member; a temporary joining step of temporarily joining a portion of a joint between the first flange and the first pipe and a portion of a joint between the second flange and the second pipe; a main welding process in which the joint between the first flange and the first pipe is welded around the entire circumference of the first pipe, and the joint between the second flange and the second pipe is simultaneously welded around the entire circumference of the second pipe.

2. The method for manufacturing a dam according to claim 1, A method for manufacturing a dam, characterized in that in the main welding process, while the first flange and the second flange are fastened together, the joint between the first flange and the first pipe and the joint between the second flange and the second pipe are welded.

3. The method for manufacturing a dam according to claim 1, In the main welding step, a connection portion between the first flange and the first pipe and a connection portion between the second flange and the second pipe are welded by a welding device that is movable in the axial direction of the first pipe and the second pipe, A method for manufacturing a dam, characterized in that the welding device is placed on a welding machine rail that is laid so as to extend in the axial direction of the first pipe and the second pipe.

4. The method for manufacturing a dam according to claim 1, the first pipe is supported by a drive roller that is driven to rotate by a drive means; the second pipe is rotatably supported by a driven roller; A method for manufacturing a dam, characterized in that the driven roller is movably mounted on a rail for a turning roll that is laid so as to extend in the axial direction of the first pipe and the second pipe.

5. The method for manufacturing a dam according to claim 1, A dam manufacturing method characterized in that, in the main welding process, the joint between the first flange and the first pipe and the joint between the second flange and the second pipe are welded using a welding device equipped with a copying device.

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