JP7386824B2 - Girder replacement method and pier removal method - Google Patents

Description

The present disclosure relates to a girder replacement method and a bridge pier removal method for a river crossing bridge.

Patent Document 1 describes a construction method for expanding the space under the girder of a river bridge. This river bridge includes a plurality of piers installed on the riverbed surface, a bridge girder provided so as to straddle the plurality of piers, and an embankment provided below the bridge girder. This method of expanding the space under the girder involves excavating the embankment and river bed, as well as implementing seismic reinforcement of the bridge piers. Next, we will erect a vent, which is a rectangular steel column, and install a scaffolding near the piers, and install a steel sandal and a hydraulic jack on top of the vent.

The steel sandals are temporary supports constructed in the shape of a parallel grid. After installing the steel sandals and hydraulic jacks, the overhead line bridge will be closed to traffic. After blocking traffic, hydraulic jacks are activated and the bridge girders are gradually jacked up while being replaced with steel sandals. That is, when the bridge girder is jacked up with a hydraulic jack and the bridge girder rises to a predetermined height, it is replaced with a steel sandal.

After cutting and removing the existing supports installed on the piers and fixing the steel frame to the top of the pier, new supports will be installed on top of the steel frame. Next, the hydraulic jacks will be activated to jack up the bridge girder again, and the load on the bridge girder will be transferred from the temporary steel sandals to the new bearings. After paving the roads at both ends of the overhead wire bridge, the traffic blockade is lifted and the series of processes is completed.

JP2009-228300A

As mentioned above, when raising the bridge girder by jacking up and replacing the steel sandals and replacing it with a newly installed support, the amount of jacking depends on the lifting capacity, so the work of replacing the girder is difficult. There is room for improvement in terms of gender. Furthermore, since the steel sandals are temporarily installed, there are concerns about earthquake resistance when the bridge girder is temporarily supported with the steel sandals.

An object of the present disclosure is to provide a girder replacement method and a pier removal method that can improve the workability of rebuilding work and improve seismic resistance.

The girder replacement method according to the present disclosure is a girder replacement method for an existing river crossing bridge, and includes the steps of installing a new main girder pedestal for raising the foundation on the existing piers, and installing the new main girder pedestal. The method includes a process of erecting a new girder on top of the bridge, a process of installing a new sleeper support girder on the new girder, and a process of removing the existing girder attached to the existing bridge pier.

In this girder replacement method, an existing river crossing bridge is replaced, and a new main girder pedestal is installed on the existing piers that make up the existing river crossing bridge. The new main girder pedestal is used to raise the foundation on top of the pier. A new girder will be erected on top of the new main girder pedestal, and a new sleeper support girder will be installed on the new girder. The existing girders attached to the existing piers will then be removed. This girder replacement method can eliminate the need for jacking up, so it is possible to improve workability by avoiding that the workability is affected by the lifting ability. The new main girder pedestal used to raise the foundation is not temporary, and with this girder replacement method, work can proceed without the use of temporary structures, making it possible to ensure high seismic resistance even during work. can.

The girder replacement method described above may include a step of removing an existing rail and an existing sleeper from an existing pier before the step of installing a sleeper support girder. In this case, before installing a new girder and installing a sleeper support girder on the new girder, the existing rail and the existing sleeper can be removed.

The girder replacement method described above may include a step of installing an existing sleeper and an existing rail on the sleeper support girder after the step of installing the sleeper support girder. In this case, the existing sleepers and the existing rails that were removed after installing the sleeper support beams can be reused. Therefore, existing sleepers and existing rails can be effectively utilized.

The existing girder may be an upper girder, and the newly installed girder may be a lower girder or a middle girder. In this case, it becomes possible to make the height of the lower surface of the newly installed girder higher than the height of the lower surface of the existing girder. Therefore, since the height of the newly installed girder relative to the river water surface can be increased, even in the event of a heavy rain disaster, it is possible to more reliably prevent the river crossing bridge from being washed away. In this way, the resistance of river crossing bridges to disasters can be increased.

The pier removal method according to the present disclosure is a pier removal method in which one of a plurality of existing piers is removed from an existing river crossing bridge, and a new main girder pedestal is installed on top of the existing pier to raise the foundation level. The process of erecting the new girder so as to straddle the pier on the new main girder pedestal, the process of installing the new sleeper support girder on the new girder, and the process of removing the existing girder that was attached to the pier. and the process of removing the bridge pier that spans the newly constructed girder.

In this pier removal method, a new main girder pedestal is installed on top of the existing pier that makes up the existing river crossing bridge, and a new girder is erected on top of the new main girder pedestal. Sleeper support girders will be installed on the new girders, and then the existing girders attached to the existing piers will be removed. Therefore, like the girder replacement method described above, jacking up is not required, so work efficiency can be improved and high earthquake resistance can be ensured even during the work. Furthermore, in this pier removal method, one of the plurality of pier piers, which is straddled by a newly installed girder, is removed. Therefore, since the number of piers in the river crossing bridge can be reduced, 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. Therefore, the resistance of the river crossing bridge to disasters can be increased.

According to the present disclosure, it is possible to improve the workability of rebuilding the bridge, and it is also possible to improve earthquake resistance.

It is a side view showing a river crossing bridge to which the girder replacement method according to the first embodiment is applied. FIG. 2 is a longitudinal cross-sectional view of the river crossing bridge in FIG. 1; FIG. 2 is a side view showing a state in which the rails of the river crossing bridge in FIG. 1 are shortened. FIG. 4 is a longitudinal cross-sectional view of the river crossing bridge in FIG. 3; FIG. 4 is a side view showing a newly installed main girder pedestal placed on the piers of the river crossing bridge shown in FIG. 3; 6 is a longitudinal sectional view of the river crossing bridge in FIG. 5. FIG. FIG. 6 is a side view showing a newly installed girder placed on the newly installed main girder pedestal of the river crossing bridge shown in FIG. 5; 8 is a longitudinal sectional view of the river crossing bridge in FIG. 7. FIG. FIG. 8 is a side view showing a state in which sleeper support girders are placed on the river crossing bridge in FIG. 7; 10 is a longitudinal sectional view of the river crossing bridge in FIG. 9. FIG. 10 is a longitudinal cross-sectional view showing a state in which sleepers are installed on the sleeper support girder of FIG. 9. FIG. 12 is a cross-sectional view taken along the line AA in FIG. 11. 10 is a side view showing a state in which the existing girder has been removed from the river crossing bridge in FIG. 9. FIG. FIG. 14 is a longitudinal sectional view of the river crossing bridge in FIG. 13; It is a side view which shows the state in which the new girder is installed in the river crossing bridge to which the girder replacement method based on 2nd Embodiment is applied. 16 is a longitudinal sectional view of the river crossing bridge in FIG. 15. FIG. FIG. 16 is a side view showing a state in which sleeper support girders are installed on the newly installed girders of the river crossing bridge shown in FIG. 15; FIG. 18 is a longitudinal cross-sectional view of the river crossing bridge in FIG. 17; FIG. 18 is a side view showing a state in which the existing girder has been removed from the river crossing bridge in FIG. 17. FIG. 20 is a longitudinal cross-sectional view of the river crossing bridge in FIG. 19; It is a longitudinal cross-sectional view showing a state in which newly installed girders are installed in a river crossing bridge according to a third embodiment. FIG. 22 is a longitudinal sectional view showing a state in which a sleeper support girder is installed on the newly installed girder shown in FIG. 21; FIG. 23 is a longitudinal cross-sectional view showing a state in which the existing girder has been removed from the river crossing bridge in FIG. 22. It is a side view which shows the river crossing bridge to which the girder replacement method and bridge pier removal method which concern on 4th Embodiment are applied. 25 is a longitudinal sectional view of the river crossing bridge in FIG. 24. FIG. FIG. 25 is a side view showing a state in which sleeper support girders are installed on the newly installed girders of the river crossing bridge shown in FIG. 24; 27 is a longitudinal sectional view of the river crossing bridge of FIG. 26. FIG. FIG. 27 is a side view showing a state in which the existing girder has been removed from the river crossing bridge in FIG. 26. FIG. 29 is a longitudinal cross-sectional view of the river crossing bridge in FIG. 28;

Below, various embodiments 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 denoted by the same reference numerals, and redundant description will be omitted as appropriate. In addition, some parts of the drawings may be simplified or exaggerated for ease of understanding, and the dimensional ratios and the like are not limited to those shown in the drawings.

(First embodiment)
FIG. 1 is a side view showing a river crossing bridge 1 in a state before the girder replacement method according to the first embodiment is executed. The river crossing bridge 1 is a railway bridge installed over the river R. FIG. 2 is a longitudinal sectional view of the river crossing bridge 1 cut along a plane orthogonal to the first direction D1 of the river crossing bridge 1. The first direction D1 is, for example, the longitudinal direction of the river crossing bridge 1 or the width direction of the river R.

As shown in FIGS. 1 and 2, the river crossing bridge 1 includes a plurality of piers 2 lined up along a first direction D1, an existing girder 3 fixed to the upper surface 2b of the plurality of piers 2, and an existing girder 3. It includes a sleeper 4 placed on the sleeper 4 and a rail 5 placed on the sleeper 4. In this embodiment, the existing girder 3 is an upper girder. The plurality of piers 2 are lined up at regular intervals along the first direction D1, and the regular intervals are, for example, about 10 m. The length of the existing girder 3 is, for example, about 10 m, and the positions of one end 3f and the other end 3g of the existing girder 3 correspond to the vertically upper part of the pier 2.

The rails 5 are installed so as to straddle the piers 2, and for example, one rail 5 is provided on top of three piers 2. For example, the positions of one end 5b and the other end 5c of the rail 5 correspond to vertically above the pier 2. The length of the existing rail 5 is, for example, about 20 m. A railway vehicle runs in a first direction D1 on a pair of rails 5 lined up along the first direction.

For example, the river R is provided with river water W and embankments E1 and E2 provided on both sides of the river water W in the first direction D1, respectively. The height of the lower end of the existing girder 3 with respect to the bottom of the river water W is, for example, about 4 m. In the river crossing bridge 1 before the girder replacement is performed, the height of the existing girder 3 with respect to the river R is low, so the height of the embankment E1 in the part where the river crossing bridge 1 is installed is suppressed.

The river crossing bridge 1 includes a pair of existing girders 3 arranged along a second direction D2 orthogonal 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 made of H-beam steel. Note that in the present disclosure, "H-shaped steel" also includes shaped steel that is slightly different from the H-shaped steel, and includes, for example, I-shaped steel. The existing girder 3 extends in the vertical direction D3 between a lower flange 3b fixed to the upper surface 2b of the pier 2, an upper flange 3c connected to the sleeper 4 and the rail 5, and the lower flange 3b and the upper flange 3c. Web 3d.

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

The connecting member 6 includes a hook bolt 6b that is inserted into the sleeper 4. 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 lined up along the second direction D2. The rail 5 is fixed onto the sleeper 4 via a tie plate 7, for example, and the tie plate 7 is fixed to the upper surface of the sleeper 4 with dog nails 8.

A method for replacing the girder of the river crossing bridge 1 configured as described above will be explained. First, as shown in FIGS. 3 and 4, the rail is shortened (step of shortening the rail). In shortening the rail, for example, the existing rail 5 having a length of about 20 m is replaced with a rail 15 long enough to work on the existing girders 3 and sleepers 4 in one day. Replacement with the rail 15 and subsequent work are performed, for example, by installing scaffolding around the pier 2.

The shortening of the rails described above is performed at night when no railway vehicles are passing, and for example, one rail 5 is removed and two rails 15 are installed in one day. The rail 15 is installed on the two piers 2, and the positions of one end 15b and the other end 15c of the rail 15 are aligned vertically above the piers 2. For example, the length of the rail 15 is about 10 m. However, the length of the rail 15 may be, for example, about 5 m, and is not particularly limited.

After the rails are shortened by installing the rails 15, as shown in FIGS. 5 and 6, a new main girder pedestal 10 is installed on the pier 2 (step of installing a new main girder pedestal). The new main girder pedestal 10 is provided to raise the foundation of the existing pier 2. The newly installed main girder pedestal 10 is, for example, a concrete structure, and is also referred to as a candle foundation.

At this time, new main girder pedestals 10 are constructed on both sides of the existing girder 3 on the upper surface 2b of the pier 2. That is, new main girder pedestals 10 are constructed on both sides of the existing girder 3 in the second direction D2. The height of the newly installed main girder pedestal 10 is, for example, about 1 m. In constructing the new main girder pedestal 10, for example, a formwork is installed on the upper surface 2b of the pier 2, and concrete is poured into the installed formwork, thereby constructing the new main girder pedestal 10. For example, construction of the newly installed main girder pedestal 10 is work that can be done even during the day when railroad cars are passing by. As an example, the period for completing construction of the new main girder pedestals 10 for all the piers 2 is about one and a half months.

After the construction of the new main girder pedestal 10 on the pier 2 is completed, the new girder 13 is erected as shown in FIGS. 7 and 8 (step of erecting a new girder). At this time, the newly installed girder 13 is installed on the upper surface of the newly constructed main girder pedestal 10. In this embodiment, the newly installed girder 13 is a lower girder. Like the existing girder 3, the new girder 13 is made of, for example, H-beam steel, and has a lower flange 13b, an upper flange 13c, and a web 13d.

The length of the newly installed girder 13 is, for example, about 10 m. The construction of the new girders 13 is performed, for example, at night when no railroad cars are passing, and as an example, two new girders 13 with one span (10 m in this embodiment) are constructed per day. One end 13f and the other end 13g of the newly installed girder 13 correspond to vertically above the pier 2 (newly installed main girder pedestal 10).

After the installation of the newly installed girder 13 is completed, as shown in FIGS. 9 and 10, a newly installed sleeper support girder 11 is installed on the newly installed girder 13 (step of installing a sleeper support girder). Specifically, the connecting member 6, sleeper 4, and rail 15 are removed from the existing girder 3 (step of removing the existing rail and the existing sleeper), and then the sleeper support girder 11 is installed on the newly installed girder 13.

The sleeper support beams 11 are installed gradually along the first direction D1, for example, at night when no railroad cars are passing. For example, depending on the situation of the river R, hanging scaffolding is installed and the sleeper support beams 11 are installed. Moreover, when installing the sleeper support girder 11 above the river water W, a hanging scaffold may be installed. The sleeper support girder 11 is installed, for example, in one span per day (in the portion between the pair of newly installed main girder pedestals 20 lined up along the first direction D1). After installing the sleeper support girder 11, the existing sleeper 4 and the existing rail 15 are installed on the sleeper support girder 11 (step of installing the existing sleeper and the existing rail).

The sleeper support girder 11 is a steel material extending in the second direction D2, and for example, each of one end and the other end of the sleeper support girder 11 is placed on the upper surface of the lower flange 13b of the newly installed girder 13. (for example, bolted). As shown in FIGS. 11 and 12, the sleeper support girder 11 is a steel material into which the sleeper 4 is inserted from vertically above and holds the inserted sleeper 4. The upper part of the installed sleeper 4 is exposed from the sleeper support girder 11.

A cross section of the sleeper support girder 11 cut along a plane extending in the first direction D1 and the vertical direction D3 has a U-shape with an opening 11g facing upward. A sleeper 4 is fitted into the opening 11g from above, and the sleeper support girder 11 holds the fitted sleeper 4. The sleeper support girder 11 has a lower plate part 11d where the lower surfaces of the fitted sleepers 4 face each other, and a pair of side plate parts 11f where the side faces of the fitted sleepers 4 face each other and are lined up along the first direction D1.

After installing the sleepers 4 on the sleeper support girders 11 as described above, the existing girders 3 are removed as shown in FIGS. 13 and 14 (step of removing the existing girders). At this time, the existing girder 3 is removed from the pier 2 by cutting the existing girder 3 and pulling out the cut existing girder 3 from below. Through the above steps, a series of steps of the girder replacement method for the river crossing bridge 1 is completed.

Next, the effects obtained from the girder replacement method according to this embodiment will be explained in detail. In the girder replacement method according to the present embodiment, an existing river crossing bridge 1 is replaced, and a new main girder pedestal 10 is installed on the existing piers 2 that constitute the existing river crossing bridge 1. The newly installed main girder pedestal 10 is for raising the foundation on the pier 2. A newly installed girder 13 is constructed on the newly installed main girder pedestal 10, and a newly installed sleeper support girder 11 is installed on the newly installed girder 13. After that, the existing girder 3 attached to the existing pier 2 is removed.

This girder replacement method can eliminate the need for jacking up, so it is possible to improve workability by avoiding that the workability is affected by the lifting ability. The new main girder pedestal 10 used to raise the foundation is not a temporary one, and with this girder replacement method, the work can proceed without using temporary structures, so high seismic resistance can be ensured even during the work. Can be done.

Furthermore, in the girder replacement method according to the present embodiment, the length of the rail 15 is changed to a length that can be completed in one day (overnight) by shortening the length of the rail 15, so that the work can be performed more efficiently. be able to. In addition, because it is possible to shorten the rail 15, erect the new girder 13, and install the sleeper girder 11 at night, the construction work can be completed in a short period of time without affecting the existing operation of the railway vehicle. This contributes to shortening the construction period. For example, construction work can be completed in a shorter period of time than when rebuilding a bridge where traffic restrictions are not possible.

The girder replacement method according to the present embodiment may include a step of removing the existing rail 15 and the existing sleeper 4 from the existing pier 2 before the step of installing the sleeper support girder 11. In this case, before installing the sleeper support girder 11 on the newly installed girder 13, the existing rail 15 and the existing sleeper 4 can be removed.

The girder replacement method according to the present embodiment may include, after the step of installing the sleeper support girder 11, a step of installing the existing sleeper 4 and the existing rail 15 on the sleeper support girder 11. In this case, the existing sleepers 4 and the existing rails 15, which were removed after installing the sleeper support girders 11, can be reused. Therefore, the existing sleepers 4 and the existing rails 15 can be effectively utilized. In the girder replacement method according to the present embodiment, newly constructed main girder pedestals 10, sleeper support girders 11, and newly installed girders 13 are used, while existing ones are used for the piers 2, sleepers 4, and rails 15. Can be done. Therefore, existing members can be effectively utilized.

In this embodiment, the existing girder 3 is an upper girder, and the newly installed girder 13 is a lower girder. In this case, the height of the lower surface of the newly installed girder 13 can be made higher than the height of the lower surface of the existing girder 3. Therefore, the height of the newly installed girder 13 relative to the water surface of the river R can be increased, so even if a heavy rain disaster or the like occurs, it is possible to more reliably prevent the river crossing bridge 1 from being washed away. In this way, the resistance of the river crossing bridge 1 to disasters can be increased.

In this embodiment, since the existing girder 3 placed on the top surface of the pier 2 is replaced with a new girder 13 placed on the top surface of the new main girder pedestal 10 on the top surface of the pier 2, the height of the new main girder pedestal 10 is The height of the lower end of the girder can be increased by the same amount. In this embodiment, the height of the new main girder pedestal 10 is about 1 m, and the height of the lower end of the existing girder 3 with respect to the bottom of the river water W is about 4 m. By increasing the height by about 1 m, the height of the lower end of the newly installed girder 13 relative to the bottom of the river water W can be set to about 5 m. As a result, for example, the lower end of the newly installed girder 13 can be made higher than the highest part of the embankment E1, thereby eliminating the need to suppress the height of the embankment E1.

(Second embodiment)
Next, a girder replacement method according to the second embodiment will be explained. Since a part of the girder replacement method according to the second embodiment overlaps with a part of the girder replacement method of the first embodiment, descriptions that overlap with the content of the first embodiment will be appropriately omitted hereinafter. As shown in FIGS. 15 and 16, in the second embodiment, the girders in the pier 22 having a narrower width (length in the second direction D2) than the pier 2 of the first embodiment are replaced.

First, as in the case of the first embodiment, after completing the installation of the shortened rail 15, the newly installed main girder pedestal 20 is installed (step of installing the newly installed main girder pedestal). The new main girder pedestals 20 are constructed on both sides of the pair of existing girders 3 on the upper surface 22b of the pier 22. The length of the newly installed main spar pedestal 20 in the second direction D2 is shorter than the length of the newly installed main spar pedestal 10 in the second direction D2 described above.

After the construction of the new main girder pedestal 20 for the pier 22 is completed, the new girder 23 is erected (step of erecting a new girder). At this time, the newly installed girder 23 is installed on the upper surface of the newly installed main girder pedestal 20. The shape of the newly installed girder 23 is different from the shape of the newly installed girder 13 described above. The newly installed girder 23 is, for example, subject to height restrictions and is lower than the height of the newly installed girder 13. In this embodiment, the newly installed girder 23 is a middle girder. The newly installed girder 23 has a lower flange 23b, an upper flange 23c, and a web 23d.

At the same time as installing the newly installed girder 23, or after installing the newly installed girder 23, the pedestal 24 is installed on the newly installed girder 23 (step of installing the pedestal). The pedestal 24 is fixed to the upper surface of the lower flange 23b of the newly installed girder 23. Specifically, it is fixed inside the lower flanges 23b of the pair of newly installed girders 23 in the second direction D2.

After the installation of the cradle 24 is completed, as shown in FIGS. 17 and 18, the sleeper holder 11 is installed on the cradle 24 (step of installing a sleeper holder). Specifically, the sleeper 4 and rail 15 are removed from the existing girder 3 (step of removing the existing rail and the existing sleeper). Thereafter, the sleeper support girder 11 is installed on the pair of support stands 24 so as to straddle the pair of support stands 24. Then, the existing sleepers 4 and the existing rails 15 are installed on the sleeper support girder 11 (step of installing the existing sleepers and the existing rails).

After installing the sleepers 4 on the sleeper support girders 11, as shown in FIGS. 19 and 20, the existing girders 3 are removed (step of removing the existing girders). Specifically, the existing girder 3 is removed from the pier 22 by cutting the existing girder 3 and pulling out the cut existing girder 3 from below. Through the above steps, a series of steps of the girder replacement method are completed.

As described above, in the girder replacement method according to the second embodiment, the newly installed girder 23 is installed on the newly installed main girder pedestal 20, the newly installed sleeper support girder 11 is installed on the newly installed girder 23, and then the existing girder 3 is removed. be done. In this series of steps, since jacking up is not required, work efficiency can be improved and high earthquake resistance can be ensured even during the work.

In this embodiment, the newly installed girder 23 is a middle girder. Therefore, the height of the lower surface of the newly installed girder 23 can be made higher than the height of the lower surface of the existing girder 3, and the height of the newly installed girder 23 relative to the water surface of the river R can be increased. Therefore, even if a heavy rain disaster or the like occurs, it is possible to more reliably prevent the river crossing bridge from being washed away, and the resistance of the river crossing bridge to disasters can be increased. Therefore, the same effects as in the first embodiment can be obtained.

(Third embodiment)
Next, a girder replacement method according to the third embodiment will be explained. As shown in FIG. 21, in the girder replacement method according to the third embodiment, the new girder 33 is installed higher than the existing girder 3, and the existing girder 3 is not completely removed. This differs from each of the above-described embodiments in that a portion is left. In the third embodiment, after completing the installation of the shortened rail 15, a new main girder pedestal 30 is constructed on the upper surface 32b of the pier 32 (step of constructing a new main girder pedestal).

Subsequently, the newly installed girder 33 is installed on the newly installed main girder pedestal 30 (a process of erecting a newly installed girder). The height of the newly installed girder 33 is higher than the height of the newly installed girder 13 described above. The newly installed girder 33 is a middle girder and has a lower flange 33b, an upper flange 33c, and a web 33d. As shown in FIG. 22, steel materials 34b, 34c, and 34d are installed on the newly installed girder 33 (step of installing steel materials). The steel members 34b, 34c, and 34d are pedestals that are sandwiched between the new girder 33 (lower flange 33b) and the existing girder 3 (upper flange of the existing girder).

Specifically, the steel material 34c is fixed to the lower surface of the lower flange 33b of one of the pair of new girders 33 and the upper flange of one of the existing girders 3 by bolts and nuts or welding, and the lower flange of the other of the pair of newly installed girders 33 is fixed. 33b, and the steel material 34d is fixed to the lower surface of the upper flange of the other existing girder 3 by bolts and nuts or welding. Then, the steel materials 34b are fixed to the lower surfaces of the upper flanges of the pair of existing girders 3, and the steel materials 34b, 34c, and 34d (three steel materials) are installed on the existing girders 3 and the new girders 33.

After installing the steel members 34b, 34c, and 34d, install the sleeper support girder 11 on the existing girder 3 and the steel members 34b, 34c, and 34d (step of installing the sleeper support girder), and install the existing sleeper 4 and the sleeper support girder 11 on the sleeper support girder 11. Install the rails 15 (process of installing existing sleepers and existing rails). Then, as shown in FIG. 23, the existing girder 3 is removed (step of removing the existing girder).

At this time, a part of the existing girder 3 will be removed. Specifically, the portions protruding downward from the steel materials 34b, 34c, and 34d of the existing girder 3 are cut, and the cut portions are removed. The portion of the existing girder 3 located between the steel members 34b, 34c, and 34d will remain. After removing a part of the existing girder 3 as described above, a series of steps of the girder replacement method are completed.

As described above, in the girder replacement method according to the third embodiment, the newly installed girder 33 is installed on the newly installed main girder pedestal 30, the sleeper support girder 11 is installed on the newly installed girder 33, and then the lower part of the existing girder 3 is removed. be done. Therefore, since jacking up is not necessary, work efficiency can be improved and high earthquake resistance can be ensured even during the work. In this embodiment, the existing girder 3 is not completely removed, and the upper part of the existing girder 3 is left in place. Therefore, a part of the existing girder 3 can be utilized for installing the sleeper support girder 11 and the sleeper 4 using the steel materials 34b, 34c, and 34d.

(Fourth embodiment)
Next, a girder replacement method and pier removal method according to the fourth embodiment will be described. As shown in FIGS. 24 and 25, in the girder replacement method according to the fourth embodiment, a new girder 43 that is higher and longer than the newly installed girder 33 of the third embodiment is installed, and a plurality of piers 42 are installed. This embodiment differs from each of the embodiments described above in that a portion is reinforced and a plurality of piers 42 are removed.

First, as in each of the embodiments described above, the rail 15 is shortened and a new main girder pedestal 40 is constructed on the upper surface 42b of the pier 42 (step of constructing a new main girder pedestal). Then, a newly installed girder 43 is installed on the upper surface of the newly installed main girder pedestal 40 (step of installing a newly installed girder). The height and strength of the newly installed girder 43 are greater than the height and strength of the newly installed girder 33 described above.

The newly installed girder 43 is a lower girder and has a lower flange 43b, an upper flange 43c, and a web 43d. The newly installed girder 43 is installed so as to straddle the piers 42 in the first direction D1, and one newly installed girder 43 is provided above the three piers 42. The positions of one end 43f and the other end 43g of the newly installed girder 43 correspond to the vertically upper part of the pier 42. The length of the newly installed girder 43 is, for example, about 20 m.

The pier 42 is reinforced at the same time as the installation of the new girder 43 or before the installation of the new girder 43 (step of reinforcing the pier). This reinforcement is not performed for all piers 42, but for example, for piers 42 that are not targeted for removal. In this embodiment, among the plurality of piers 42 lined up along the first direction D1, one end 43f and the other end 43g of the newly installed girder 43 reinforce the piers 42 located above.

The reinforcement of the pier 42 is performed, for example, by rolling reinforcement in which a reinforcing member 50 is constructed on the outer peripheral surface of the pier 42. The rolling reinforcement may be steel plate rolling reinforcement or RC (Reinforced Concrete) rolling reinforcement. Moreover, the reinforcement of the pier 42 may be performed by a method other than rolling reinforcement.

As an example, the pier 42 may be reinforced by inserting a steel rod by forming an excavation hole in the pier 42 from vertically above and inserting a steel rod into the excavation hole. In this case, enlargement of the outer peripheral surface of the pier 42 can be suppressed. However, from the viewpoint of quickly and more reliably reinforcing the pier 42 while suppressing an increase in cost, it is preferable to reinforce the pier 42 by rolling reinforcement.

After constructing the new girder 43 and reinforcing the bridge pier 42, as shown in FIGS. 26 and 27, the sleeper support girder 11 is installed on the new girder 43 (step of installing a sleeper support girder). At this time, as described above, the connecting member 6, sleeper 4, and rail 15 are removed from the existing girder 3 (step of removing the existing rail and the existing sleeper), and then the lower flanges 43b of each of the pair of new girders 43 are removed. A sleeper support girder 11 is installed on top (step of installing a sleeper support girder). After installing the sleeper support girder 11 on the newly installed girder 43, the existing sleeper 4 and the existing rail 15 are installed on the sleeper support girder 11 (step of installing the existing sleeper and existing rail).

Thereafter, as shown in FIGS. 28 and 29, the existing girder 3 is removed (step of removing the existing girder). The pier 42 is removed along with or after the removal of the existing girder 3 (a step of removing the pier). At this time, the unreinforced pier 42 is removed from the newly installed girder 43. Specifically, the unreinforced piers 42 located between the pair of reinforced piers 42 (provided with the reinforcing members 50) arranged along the first direction D1 are removed. Through the above steps, a series of steps for girder replacement and bridge pier removal are completed.

As described above, in the girder replacement method according to the fourth embodiment, the newly installed girder 43 is installed on the newly installed main girder pedestal 40, the sleeper support girder 11 is installed on the newly installed girder 43, and then the existing girder 3 is removed. . Therefore, like each of the embodiments described above, workability can be improved and high earthquake resistance can be ensured even during work. Furthermore, in this embodiment, a new girder 43 that is larger and more rigid than the existing girder 3 is constructed. Therefore, the number of piers 42 can be reduced by reinforcing some of the piers 42 and removing the remaining parts.

That is, in the bridge pier removal method according to the present embodiment, the new main girder pedestal 40 is installed on the existing pier 42 constituting the existing river crossing bridge, and the newly installed girder 43 is installed on the new main girder pedestal 40. Ru. The sleeper support girder 11 is installed on the new girder 43, and then the existing girder 3 attached to the existing pier 42 is removed. Then, one of the plurality of piers 42 and over which the newly installed girder 43 straddles (the pier 42 in which one end and the other end of the newly installed girder 43 are not located vertically above) is removed.

Therefore, since the number of piers 42 in the river crossing bridge can be reduced, it is possible to more reliably prevent the river crossing bridge from being washed away even in the event of a heavy rain disaster. In other words, the span of the piers 42 can be expanded compared to before the girder replacement, and the resistance of the flow of the river R that the river crossing bridge receives can be reduced, so the resistance of the river crossing bridge to heavy rain disasters etc. can be increased. It can be made stronger.

Various embodiments of the girder replacement method and pier removal method according to the present disclosure have been described above. However, the present disclosure is not limited to the embodiments described above, and may be modified or applied to other things without changing the gist of each claim. That is, the content and order of the steps in the girder replacement method and the pier removal method can be changed as appropriate without departing from the above gist.

For example, in the above description, a pier removal method for removing a portion of the plurality of pier piers 42 in the girder replacement method of the fourth embodiment has been described. However, the pier removal method according to the present disclosure may be performed in the girder replacement method of the first embodiment, second embodiment, or third embodiment described above. In this case, even in the first to third embodiments, a river crossing bridge that is resistant to heavy rain disasters can be constructed by widening the span of the piers.

1... River crossing bridge, 2, 22, 32, 42... Pier, 2b, 22b, 32b, 42b... Top surface, 3... Existing girder, 3b... Lower flange, 3c... Upper flange, 3d... Web, 3f... One end, 3g ...Other end, 4...Sleeper, 5...Rail, 5b...One end, 5c...Other end, 6...Connecting member, 6b...Hook bolt, 6c...Hook portion, 7...Tie plate, 8...Dog nail, 10, 20, 30 , 40... Newly installed main girder pedestal, 11... Sleeper support girder, 11d... Lower plate part, 11f... Side plate part, 11g... Opening, 13, 23, 33, 43... Newly installed girder, 13b, 23b, 33b, 43b... Lower flange , 13c, 23c, 33c, 43c...upper flange, 13d, 23d, 33d, 43d...web, 13f, 43f...one end, 13g, 43g...other end, 15...rail, 15b...one end, 15c...other end, 24... cradle, 34b, 34c, 34d... steel material, 50... reinforcing member, D1... first direction, D2... second direction, D3... vertical direction, E1... embankment, E2... embankment, R... river, W... river water.

Claims (5)

A girder replacement method for an existing river crossing bridge, the method comprising:
The process of installing a new main girder pedestal to raise the foundation on top of the existing pier;
a step of erecting a new girder on the new main girder pedestal;
a step of installing a newly installed sleeper support girder on the newly installed girder;
a step of removing an existing girder attached to the existing bridge pier;
How to replace the girder. Before the step of installing the sleeper support girder, a step of removing the existing rail and the existing sleeper from the existing bridge pier,
The girder replacement method according to claim 1. After the step of installing the sleeper support girder, a step of installing the existing sleeper and the existing rail on the sleeper support girder,
The girder replacement method according to claim 2. The existing girder is an upper girder,
The newly installed girder is a lower girder or a middle girder,
The girder replacement method according to any one of claims 1 to 3. A pier removal method for removing one of a plurality of existing piers from an existing river crossing bridge, the method comprising:
The process of installing a new main girder pedestal to raise the foundation on top of the existing pier;
erecting a new girder on the new main girder pedestal so as to straddle the pier;
a step of installing a newly installed sleeper support girder on the newly installed girder;
a step of removing the existing girder attached to the pier;
a step of removing the bridge pier that spans the newly constructed girder;
Bridge pier removal method.

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