How to replace the girder

Abstract

To provide a girder replacement method with which construction period can be shortened, cost can be reduced and working space can be reduced.SOLUTION: A girder replacement method according to an embodiment is a girder replacement method of a cross-river bridge 1 that includes multiple existing bridge abutments 2 lined up along the width direction of a river R and an existing girder 3 across the existing abutments 2. The girder replacement method includes a step of installing a construction girder 10 on the areas of ground G on both sides of a first direction D1 when viewed from the river R, a step of constructing new abutments 20 at the bottom of each construction girder 10, a step of installing a new girder 30 above the existing abutments 2 and the new abutments 20, a step of removing the construction girder 10 installed on the ground G and installing a sleeper support girder 40 on the newly installed girder 30 above the ground G and a step of removing the existing girder 3 and installing the sleeper support girder 40 on the new girder 30 above the river R.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present disclosure relates to a method for replacing a girder of a river crossing bridge. [Background technology]

[0002] Japanese Patent Application Laid-Open Publication No. 59-195908 describes a bridge girder horizontal installation method in which a bridge girder manufactured in a factory or at the construction site is sent to the installation position on the bridge pier perpendicular to the bridge axis by a sending-out device such as a horizontal jack. In the horizontal installation method, the bridge girder is placed on the bridge pier at the installation position via a rail bed.

[0003] The rail bed is arranged to extend from the pier in a direction perpendicular to the bridge axis. The bridge girder is placed on the rail bed. The bridge girder is then sent to the installation position by the above-mentioned sending device. At the installation position, the bridge girder is lifted, and then the rail bed is removed. Permanent bearings are installed between the bridge girder and the pier, and the bridge girder is supported by these bearings. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 59-195908 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the conventional girder replacement method, it is sometimes necessary to construct new abutments on both sides of the existing abutment, convert them into construction girders, remove the existing abutment, and construct a lateral transfer facility before carrying out the above-mentioned lateral transfer erection method. Thus, when carrying out the lateral transfer erection method, the current situation is that the preliminary work is complicated, the construction period is prolonged, and costs are increasing.

[0006] In addition, with the side-loading erection method, because the bridge girder is moved perpendicular to the bridge axis for erection work, it is necessary to secure work space on both sides of the existing abutment in the direction perpendicular to the bridge axis. Furthermore, the above-mentioned side-loading equipment requires the arrangement of piping for hydraulic horizontal jacks, which also requires a large work space.

[0007] The present disclosure aims to provide a girder replacement method that can shorten construction time, reduce costs, and reduce work space. [Means for solving the problem]

[0008] The girder replacement method according to the present disclosure is a method for replacing girders of a river crossing bridge that includes multiple existing abutments aligned along the width direction of the river and existing girders that span the multiple existing abutments. The girder replacement method includes the steps of installing construction girders on the ground located on both sides of the width direction as viewed from the river, constructing new abutments under each construction girder, installing new girders above the multiple existing abutments and the multiple new abutments, removing the construction girders installed on the ground and installing sleeper support girders on the new girders located above the ground, and removing the existing girders and installing sleeper support girders on the new girders located above the river.

[0009] In this girder replacement method, construction girders are installed on the ground located on both sides of the river in the width direction, and new abutments are constructed under each construction girder. Since the new abutments are constructed on both sides of the river in the width direction from the multiple existing abutments, the width of the river can be widened. Therefore, the river flow rate can be increased to suppress flooding of the river. After the new abutments are constructed, new girders are installed on the multiple existing abutments and the multiple new abutments. Then, the construction girders installed on the ground are removed and sleeper support girders are installed on the new girders located above the ground, and the existing girders are removed and sleeper support girders are installed on the new girders located above the river. By installing sleeper support girders on the new girders through the above process, it is possible to eliminate the need for lateral installation that moves the bridge girder in the direction perpendicular to the bridge axis. Therefore, the preliminary work can be simplified, and the construction period can be shortened and costs can be reduced. Furthermore, since lateral installation equipment such as horizontal jacks can be eliminated, the work space on both sides of the river in the width direction can be reduced.

[0010] The girder replacement method may include a step of removing multiple existing abutments after a step of installing a sleeper support girder on a new girder located above the ground and a step of installing a sleeper support girder on a new girder located above the river. In this case, since multiple existing abutments are removed, the river cross-section obstruction rate can be reduced and the water flow rate in the river can be further increased, so that floods in the river can be more reliably suppressed.

[0011] The girder replacement method may include a step of installing a temporary girder support for temporarily supporting the new girder on the existing abutment before the step of installing the new girder. In this case, the new girder installed above the existing abutment can be temporarily supported by the temporary girder support.

[0012] The previously mentioned existing girder may be an upper deck girder, and the previously mentioned new girder may be a lower deck girder. In this case, it is possible to make the height of the underside of the new girder higher than the height of the underside of the existing girder. Therefore, since the height of the new girder relative to the water level of the river can be made higher, it is possible to more reliably prevent the river crossing bridge from being washed away even in the event of a heavy rain disaster or the like. In this way, the resistance of the river crossing bridge to disasters can be improved. Effect of the Invention

[0013] According to the present disclosure, construction time can be shortened, costs can be reduced, and work space can be reduced. [Brief description of the drawings]

[0014] [Figure 1] 1(a) is a side view showing a river crossing bridge to which a girder replacement method according to an embodiment is applied, and FIG. 1(b) is a plan view showing the river crossing bridge of FIG. [Diagram 2] FIG. 1(a) is a longitudinal cross-sectional view of the river crossing bridge. [Diagram 3] 1(a) is a side view showing the state in which a construction girder is installed on the river crossing bridge in Fig. 1(a), and (b) is a plan view showing the river crossing bridge in Fig. 3(a). [Figure 4] 4(a) is a side view showing the state in which a new abutment has been installed on the river crossing bridge in Fig. 3(a), and (b) is a plan view showing the river crossing bridge in Fig. 4(a). [Diagram 5] (a) is a vertical cross-sectional view showing the existing girder, temporary girder support, and rail placed on the existing abutment, and (b) is a vertical cross-sectional view showing the ballast and rail placed on the ground located on both sides of the river width. [Figure 6] 5(a) is a side view showing the state in which a new girder has been installed on the river crossing bridge in Fig. 5(a), and Fig. 6(b) is a plan view showing the river crossing bridge in Fig. 6(a). [Figure 7] 5(a) is a vertical cross-sectional view showing a state where a new girder is placed on the temporary girder support in FIG. 5(a), and FIG. 5(b) is a vertical cross-sectional view showing a state where a new girder is placed on the ground in FIG. 5(b). [Figure 8] 8(a) is a plan view showing the state in which a sleeper support girder is installed on a new girder located above the ground in the river crossing bridge in FIG. 6(b), and FIG. 8(b) is a plan view of the state in FIG. 8(a). [Figure 9]7(a) is a longitudinal cross-sectional view showing the state where the ballast has been removed from the river crossing bridge in Fig. 7(b) and a sleeper support girder has been installed. 8(b) is a longitudinal cross-sectional view showing the state where a sleeper support girder has been installed on a new girder located above the river in the river crossing bridge in Fig. 8. [Figure 10] FIG. 8(b) is a plan view showing a state in which a sleeper support girder has been installed on the newly installed girder in FIG. [Figure 11] This is a plan view showing the state in which a sleeper support girder is installed on a newly constructed girder located above the river and above the ground. [Figure 12] 12(a) is a side view showing the state where the construction girder of the river crossing bridge has been further removed, and (b) is a side view showing the state where the existing abutment has been removed from the river crossing bridge in FIG. 12(a). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, an embodiment of the girder replacement method according to the present disclosure will be described with reference to the drawings. In the description of the drawings, the same or corresponding elements are given the same reference numerals, and duplicated descriptions are omitted as appropriate. In addition, the drawings may be partially simplified or exaggerated for ease of understanding, and the dimensional ratios and the like are not limited to those shown in the drawings.

[0016] Fig. 1(a) is a side view showing the river crossing bridge 1 before the girder replacement method according to the embodiment is performed. Fig. 1(b) is a plan view showing the river crossing bridge 1. Fig. 2 is a longitudinal sectional view of the river crossing bridge 1 cut by a plane perpendicular to a first direction D1 in which the river crossing bridge 1 extends. The first direction D1 is the longitudinal direction of the river crossing bridge 1 or the width direction of the river R.

[0017] 1(a), 1(b) and 2, the river crossing bridge 1 comprises a plurality of existing abutments 2 lined up along a first direction D1, existing girders 3 fixed to the plurality of existing abutments 2, sleepers 4 placed on the existing girders 3, and rails 5 placed on the sleepers 4. In this embodiment, the existing girders 3 are deck girders. The plurality of existing abutments 2 are lined up along the first direction D1.

[0018] For example, the existing abutment 2 has a recess 2b on which the existing girder 3 is placed, and a protrusion 2c located at both ends of the recess 2b in the first direction D1 of the existing abutment 2. As an example, the length of the existing girder 3 is about 10 m. One end 3f and the other end 3g of the existing girder 3 are positioned vertically above the existing abutment 2. The river crossing bridge 1 is equipped with a plurality of rails 5, which extend vertically above the existing abutment 2 in the first direction D1. A railway vehicle V runs on the multiple rails 5 in the first direction D1.

[0019] River water W flows in the river R. The river crossing bridge 1 has a pair of existing girders 3 aligned along a second direction D2 perpendicular to the first direction D1. The second direction D2 is, for example, the width direction of the river crossing bridge 1 or the direction in which the river R flows. For example, the existing girder 3 is an H-shaped steel. The existing girder 3 has a lower flange 3b fixed to the upper surface 2d of the recess 2b of the existing abutment 2, an upper flange 3c connected to the sleepers 4 and the rail 5, and a web 3d extending in the vertical direction D3 between the lower flange 3b and the upper flange 3c.

[0020] The sleepers 4 are arranged at regular intervals along the first direction D1. Each sleeper 4 extends along the second direction D2. The regular interval is, for example, about 0.6 m. The river crossing bridge 1 is provided with a connecting member 6 that connects the sleepers 4 to the upper flange 3c of the existing girder 3. For example, a pair of connecting members 6 are provided that are arranged along the second direction D2.

[0021] The connecting member 6 includes a hook bolt 6b that connects the sleeper 4 to the upper flange 3c of the existing girder 3. A hook portion 6c that is hooked onto the upper flange 3c of the existing girder 3 is provided at the lower end of the hook bolt 6b. The river crossing bridge 1 includes a pair of rails 5 aligned along the second direction D2. The rails 5 are fixed onto the sleepers 4, for example, via tie plates 7, and the tie plates 7 are fixed to the upper surfaces of the sleepers 4 with dog spikes 8.

[0022] Next, a method for replacing girders of the river crossing bridge 1 will be described. In the girder replacement method according to this embodiment, the river R is widened. That is, in the girder replacement method according to this embodiment, construction work is carried out to widen the river R. As a specific example, the frequency of heavy rain or short-term heavy rain has been increasing, particularly in recent years, and there is a demand for improving the flow capacity of the river water W in the river R. In the girder replacement method according to this embodiment, the river R is widened, thereby making it possible to improve the flow capacity of the river water W.

[0023] First, as shown in Figures 3(a) and 3(b), construction girders 10 are installed on each of the ground G located in the earthwork section P1, which is the portion on both sides in the first direction D1 as seen from the river R (step of installing construction girders). At this time, for example, the ground G is excavated to build a retaining wall 11, and the construction girders 10 are installed inside the retaining wall 11 in a plan view.

[0024] For example, the construction girder 10 has a pair of first girder members 12 extending along a first direction D1 and aligned along a second direction D2, a pair of second girder members 13 extending along the second direction D2 at the lower part of the first girder members 12 and aligned along the first direction D1, and a plurality of piles 14 extending downward from each of the second girder members 13.

[0025] Furthermore, the construction girder 10 has a plurality of sleepers 15 arranged along the first direction D1 on the upper part of the first girder material 12. In a plan view, an earth retaining wall 11 is constructed to surround the first girder material 12, the second girder material 13, and the plurality of sleepers 15. The earth retaining wall 11 is, for example, a pile or a sheet pile. Also, the pile 14 may function as an earth retaining wall.

[0026] Next, as shown in Figures 4(a) and 4(b), a new abutment 20 is constructed under each construction girder 10 (step of constructing a new abutment). At this time, the new abutment 20 is constructed under the first girder 12 in each civil engineering section P1. The height (depth) of the new abutment 20 is higher than the height of the existing abutment 2.

[0027] Fig. 5(a) shows a longitudinal section of bridge section P2, which is the portion located above river R. Fig. 5(b) is a longitudinal section of a portion of earthwork section P1 where construction girder 10 has not been constructed. As shown in Fig. 5(b), earthwork section P1 is equipped with ballast B provided on ground G, and rails 5 are laid on ballast B. Also, as shown in Figs. 4(a), 4(b) and 5(a), temporary girder supports 35 are installed on existing abutment 2 to temporarily support new girder 30, which will be described later (step of installing temporary girder supports).

[0028] The temporary girder supports 35 are installed on both sides in the second direction D2 as viewed from the pair of existing girders 3. For example, the temporary girder supports 35 are installed on an upper surface 2d of the recess 2b of the existing abutment 2. As an example, the temporary girder supports 35 include a first member 36 extending in the second direction D2 on the upper surface 2d of the recess 2b, a second member 37 fixed to the upper surface of the first member 36, and a third member 38 fixed to the upper surface of the second member 37.

[0029] For example, the first member 36, the second member 37, and the third member 38 are steel materials. However, the temporary girder support 35 is not limited to including the first member 36, the second member 37, and the third member 38, and the configuration, shape, and the like of the temporary girder support 35 are not particularly limited. The temporary girder support 35 may be a newly constructed main girder base provided to raise the height of the existing abutment 2, or may be a concrete structure. The temporary girder support 35, which is a concrete structure, is also called a candle foundation.

[0030] Next, as shown in Figures 6(a), 6(b), 7(a) and 7(b), a new girder 30 is installed above the multiple existing abutments 2 and the multiple new abutments 20 (step of installing new girders). At this time, the new girder 30 is installed on the upper surface of the constructed temporary girder support 35 (e.g., third member 38). In this embodiment, the new girder 30 is a through girder.

[0031] The new girder 30, like the existing girder 3, is, for example, an H-shaped steel, and has a lower flange 31, an upper flange 32, and a web 33. As an example, the new girder 30 includes a first new girder 30A provided in the bridge section P2 and a second new girder 30B provided in the civil work section P1. For example, the length of the first new girder 30A is longer than the distance between a pair of existing abutments 2 aligned along the first direction D1.

[0032] For example, the first new girder 30A is provided so as to protrude on both sides in the second direction D2 beyond the river R before widening. The second new girder 30B is provided on each side of the first new girder 30A in the second direction D2. For example, the length of the second new girder 30B is shorter than the length of the first new girder 30A. The second new girder 30B is installed so as to extend from the end of the first new girder 30A in the first direction D1 to the new abutment 20. In the earthwork section P1, new girders 30 are installed on both sides of the ballast B in the second direction D2.

[0033] After the installation of the new girder 30 is completed, as shown in Fig. 8(a), Fig. 8(b) and Fig. 9(a), in one of the pair of earthwork sections P1 (the left side in Fig. 8(b)), the construction girder 10 is removed (a step of removing the construction girder), and the sleeper support girder 40 is installed (a step of installing the sleeper support girder). For example, the ballast B located between the pair of new girders 30 is removed, and the sleeper support girder 40 is installed on the pair of new girders 30. In the earthwork section P1, the sleeper support girder 40 is placed on the upper surface of the pair of lower flanges 31 and is installed so as to extend along the second direction D2 between the pair of new girders 30. After the installation of the sleeper support girder 40, the sleepers 4 are installed on the sleeper support girder 40, and the rails 5 are installed on the sleepers 4 (a step of installing the sleepers and rails).

[0034] The sleeper support girder 40 is a steel material extending in the second direction D2. For example, one end and the other end of the sleeper support girder 40 are placed on the upper surface of the lower flange 31 of the newly-installed girder 30 and fixed (for example, bolted) to the newly-installed girder 30. For example, the sleeper support girder 40 is a steel material with a U-shaped cross section into which the sleeper 4 is inserted vertically from above and holds the inserted sleeper 4. The upper part of the installed sleeper 4 is exposed from the sleeper support girder 40. For example, the cross section of the sleeper support girder 40 cut on a plane extending in the first direction D1 and the vertical direction D3 is U-shaped with an opening facing upward. The sleeper 4 is fitted into this opening from above, and the sleeper support girder 40 holds the fitted sleeper 4.

[0035] Next, as shown in FIG. 9(b) and FIG. 10, in the bridge section P2, the existing girder 3 is removed (step of removing the existing girder), and the sleeper support girder 40 is installed (step of installing the sleeper support girder). Specifically, the connecting member 6, sleeper 4, and rail 5 are once removed from the existing girder 3 (step of removing the existing rail and the existing sleeper), and then the sleeper support girder 40 is installed on the new girder 30. The installation of the sleeper support girder 40 in the bridge section P2 is performed, for example, overnight during the night when the railcar V is not running. For example, the installation of the sleeper support girder 40 is performed gradually along the first direction D1. After the sleeper support girder 40 is installed, the existing sleeper 4 and the existing rail 5 are installed on the sleeper support girder 40 in the same manner as described above (step of installing the existing sleeper and the existing rail).

[0036] 11 and 12(a), in the other of the pair of earthwork sections P1 (the right side in FIG. 11), the construction girder 10 is removed (a process of removing the construction girder) and a sleeper support girder 40 is installed (a process of installing the sleeper support girder). Then, as described above, the sleepers 4 are installed on the sleeper support girder 40, and the rails 5 are installed on the sleepers 4 (a process of installing the sleepers and rails).

[0037] As described above, after the rails 5 are installed on the sleeper support girders 40 located above the ground G (earthwork section P1) and the rails 5 are installed on the sleeper support girders 40 located above the river R (bridge section P2), the existing abutments 2 are removed (step of removing the existing abutments), for example, as shown in Fig. 12(b). At this time, the multiple existing abutments 2 located between the pair of new abutments 20 are removed.

[0038] More specifically, the temporary girder supports 35 installed on the existing abutment 2 are removed (step of removing the temporary girder supports), and then the existing abutment 2 is removed. By removing multiple existing abutments 2 as described above, the river R can be widened and deepened to the height of the bottom of the new abutment 20, thereby increasing the flow rate of the river water W in the river R. Through the above steps, a series of steps in the girder replacement method according to this embodiment is completed.

[0039] Next, the effects obtained from the girder replacement method according to this embodiment will be described in detail. In the girder replacement method according to this embodiment, construction girders 10 are installed on the ground G located on both sides in the first direction D1 (width direction) as viewed from the river R, and new abutments 20 are constructed below each construction girder 10. Since the new abutments 20 are constructed on both sides of the river R in the first direction D1 as viewed from the multiple existing abutments 2, the width of the river R can be expanded.

[0040] Therefore, the flow rate of the river water W of the river R can be increased to suppress floods of the river R. After constructing the new abutments 20, the new girders 30 are installed on the multiple existing abutments 2 and the multiple new abutments 20. After that, the construction girder 10 (the construction girder 10 in the civil work section P1) installed on the ground G is removed, and the sleeper support girder 40 is installed on the new girder 30 located above the ground G, and the existing girder 3 is removed and the sleeper support girder 40 is installed on the new girder 30 located above the river R. By installing the sleeper support girder 40 on the new girder 30 through the above process, the conventional lateral installation can be eliminated. Therefore, the advance work can be simplified, and the construction period can be shortened and the cost can be reduced. Furthermore, since lateral installation equipment such as horizontal jacks can be eliminated, the work space on both sides of the width of the river can be reduced.

[0041] The girder replacement method according to this embodiment includes a step of installing a sleeper support girder 40 on a new girder 30 located above the ground G (earthwork section P1), and a step of installing the sleeper support girder 40 on a new girder 30 located above the river R (bridge section P2), followed by a step of removing multiple existing abutments 2. Since multiple existing abutments 2 are removed, the river cross-section obstruction rate can be reduced and the flow rate of river water W in the river R can be further increased, so that floods in the river R can be more reliably suppressed.

[0042] The girder replacement method according to this embodiment includes a step of installing a temporary girder support 35 for temporarily supporting the new girder 30 on the existing abutment 2 before the step of installing the new girder 30. Therefore, the new girder 30 installed on the top of the existing abutment 2 can be temporarily supported by the temporary girder support 35.

[0043] In this embodiment, the existing girder 3 is an upper deck girder, and the new girder 30 is a lower deck girder. Therefore, it is possible to make the height of the underside of the new girder 30 higher than the height of the underside of the existing girder 3. Therefore, since the height of the new girder 30 relative to the water level of the river R can be increased, it is possible to more reliably prevent the river crossing bridge 1 from being washed away even in the event of a heavy rain disaster or the like. In this way, the resistance of the river crossing bridge 1 to disasters can be increased.

[0044] The embodiment of the girder replacement method according to the present disclosure has been described above. However, the present disclosure is not limited to the above-mentioned embodiment, and may be modified or applied to other things within the scope of the gist described in each claim. In other words, the content and order of the steps of the girder replacement method can be appropriately changed within the scope of the gist described above.

[0045] For example, in the above embodiment, an example in which the existing abutment 2 is removed has been described. However, the existing abutment 2 may be left in place without being removed. In the above embodiment, an example in which the new girder 30 includes the first new girder 30A and a pair of second new girders 30B shorter than the first new girder 30A has been described. However, the length of the first new girder 30A and the length of the second new girder 30B may be the same as each other. In addition, instead of the first new girder 30A and the second new girder 30B, a single new girder extending from one new abutment 20 to the other new abutment 20 along the first direction D1 may be provided. In this case, it is also possible to eliminate the need for the temporary girder support 35. As described above, the form of the new girder can be changed as appropriate.

[0046] In the above embodiment, an example has been described in which the installation of the sleeper support girder 40 on one of the pair of earthwork sections P1, the installation of the sleeper support girder 40 on the bridge section P2, and the installation of the sleeper support girder 40 on the other of the pair of earthwork sections P1 are performed in this order. However, for example, the installation of the sleeper support girder 40 on one of the pair of earthwork sections P1 and the installation of the sleeper support girder 40 on the other of the pair of earthwork sections P1 may be performed simultaneously, and the timing of installation of the sleeper support girder 40 on each section can be changed as appropriate. [Explanation of symbols]

[0047] 1...River crossing bridge, 2...Existing abutment, 2b...Concave portion, 2c...Convex portion, 2d...Top surface, 3...Existing girder, 3b...Lower flange, 3c...Upper flange, 3d...Web, 3f...One end, 3g...Other end, 4...Sleeper, 5...Rail, 6...Connecting member, 6b...Hook bolt, 6c...Hook portion, 7...Tie plate, 8...Peg, 10...Construction girder, 11...Earth retaining, 12...First girder material, 13...Second girder material, 14...Pile, 15...Sleeper, 20 ...New abutment, 30...New girder, 30A...First new girder, 30B...Second new girder, 31...Lower flange, 32...Upper flange, 33...Web, 35...Temporary girder support, 36...First member, 37...Second member, 38...Third member, 40...Sleeper support girder, B...Ballast, D1...First direction (width direction), D2...Second direction, D3...Vertical direction, G...Ground, P1...Earthwork section, P2...Bridge section, R...River, V...Railway vehicle, W...River water.

Claims

1. A method for replacing girders of a river crossing bridge having a plurality of existing abutments arranged along the width direction of the river and existing girders spanning the plurality of existing abutments, comprising the steps of: A step of installing construction girders on each of the grounds located on both sides in the width direction as viewed from the river; A step of constructing a new abutment under each of the construction girders; Installing new girders above the plurality of existing abutments and the plurality of new abutments; A step of removing the construction girder installed on the ground and installing a sleeper support girder on the newly installed girder located above the ground; removing the existing girder and installing a sleeper support girder on the new girder located above the river; A method for replacing a girder comprising the steps of:

2. The method includes a step of installing the sleeper support girder on the newly constructed girder located above the ground, and a step of removing the multiple existing abutments after the step of installing the sleeper support girder on the newly constructed girder located above the river. The method for replacing a girder according to claim 1.

3. Prior to the step of installing the new girder, a step of installing a temporary girder support for temporarily supporting the new girder on the existing abutment is provided. The method for replacing a girder according to claim 1 or 2.

4. The existing girder is an upper deck girder, The newly installed girder is a through girder, The method for replacing a girder according to any one of claims 1 to 3.

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