JP2017203284A - Bridge widening method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bridge widening method which can shorten the construction period.SOLUTION: A bridge widening method for bridges which have concrete floor slabs arranged to span abutments or piers, comprises: a preloading process which holds at least one side of an existing floor slab 11, the side facing a new floor slab 12 and being applied with upward load; a forming process of the new floor slab 12, in which concrete is cast while the new floor slab 12 for the widening is placed adjacently to the existing floor slab 11 with the level held practically the same as the holding level of the existing floor slab 11 set during the preloading process; and a hold-release process which releases the holding of the existing floor slab 11 and the new floor slab 12 after casting concrete.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a bridge widening method for widening an RC floor slab bridge.

  There are road bridges as well as railway bridges. The latter road bridge may require widening. In that case, there is a high demand for adopting a method of widening the existing floor slab while permitting the traveling of a general vehicle without blocking traffic or restricting traveling.

  Conventionally, in consideration of a live load caused by traveling of a vehicle on an existing floor slab and vibration associated therewith, a method of installing a new floor slab apart from an existing floor slab is generally employed.

An example of widening the conventional road and road bridge will be described with reference to FIGS.
First, as shown in FIG. 1, (1) the roads 1 and 2 before and after the bridge are widened. The existing floor slab 11 of the road bridge 3 is subjected to its own weight and a live load due to vehicle travel, and the central portion bends downward, causing vibration every time the vehicle travels.

  Next, as shown in FIG. 2, (2) the new primary floor slab 12 and the rebar are installed separately from the existing floor slab 11. In this case, the formwork and reinforcing bars of the primary floor slab 12 are supported by the formwork support 4 (illustrated schematically by arrows) to maintain the plane of the formwork of the primary floor slab 12.

  Thereafter, (3) In this state, concrete is placed in the mold of the primary floor slab 12, and curing is performed until a predetermined strength is developed.

  Next, the support by the mold support 4 is released. Thereby, as shown in FIG. 3, the primary floor slab 12 is bent downward by its own weight.

  Finally, as shown in FIG. 4, (4) the formwork of the secondary floor slab 13 is installed between the existing floor slab 11 and the primary floor slab 12 that are bent downward, and concrete is placed in the form. , Plan the curing.

  Finally, (5) waiting for the expression of a predetermined strength, the wide bridge part is used.

  In this conventional example, after casting concrete into the primary floor slab 12, after waiting for the strength to be developed, the formwork supporter 4 is removed to release its own weight, and the subsequent creep and drying shrinkage can be accommodated to some extent. Since it is necessary to wait, it usually takes about three months until the start of placing concrete into the secondary floor slab 13.

Japanese Patent No. 3806951

However, there are many requests to use it as soon as possible.
Then, the main subject of this invention is providing the widening method which can aim at shortening of a construction period, preventing the influence from the existing floor slab side.

The present invention for solving the above-mentioned problems is in the case of widening a bridge in which a concrete floor slab is arranged across between abutments or piers,
A preloading process in which at least the new floor slab side of the existing floor slab is held with an upward load;
A holding step of holding the formwork of the new floor slab for widening adjacent to the existing floor slab and holding the level thereof substantially the same as the holding level of the existing floor slab in the preloading step;
A new floor slab forming process in which concrete is placed in the formwork of the new floor slab for widening together with or after the holding process;
A holding release step for releasing the holding of the existing floor slab and the holding of the new floor slab after the new floor slab forming step;
It is a construction method to widen the bridge with

As described above, the existing floor slab 11 of the road bridge 3 is bent downward by its own weight. In addition, for example, when vehicle traffic is permitted during the widening work, a live load is applied due to vehicle travel, and vibration occurs every time the vehicle travels. As a result, if a new floor slab is installed adjacent to the existing floor slab 11 and concrete placement is performed, the generated vibration propagates to the new floor slab each time the vehicle travels, and during the concrete placement and curing process. May adversely affect the quality of the concrete plate.
However, the present invention includes a preloading step in which at least the new floor slab side of the existing floor slab is held with an upward load. Therefore, even when, for example, vehicle traffic is permitted during the widening work, it is possible to prevent the live load caused by the vehicle running from causing vibration and causing the influence to propagate to the new floor slab side.

On the other hand, according to the present invention, the formwork of the new floor slab for widening is placed adjacent to the existing floor slab, and the level thereof is held substantially the same as the holding level of the existing floor slab in the preloading process. It has the process of forming a new floor slab by performing concrete placement in the formwork of the new floor slab for widening after a process.
Therefore, after the new floor slab forming step, even when the holding of the existing floor slab and the holding of the new floor slab are released, it can be similarly bent downward to maintain the road surface uniformity.

In the present invention, it is desirable to take a form in which a plurality of support portions are provided in the longitudinal direction of the bridge while being supported by a joist straddling the existing floor slab and the newly installed floor slab.
When supported by the joist straddling the existing floor slab and the new floor slab, the new floor slab follows the vibration from the existing floor slab to the new floor slab, preloading the existing floor slab, and the existing floor slab. The combined effect of maintaining the same level of the plate and the newly installed floor slab will be prominent.

While supporting by the joist straddling the existing floor slab and the newly installed floor slab, there are a plurality of support portions in the longitudinal direction of the bridge,
In a preloading step in which at least a new floor slab side of an existing floor slab is held by applying an upward load, a form in which jacking up from below the holding material for supporting the plurality of joists is performed for preloading.
It is possible to preload and support with joist timber straddling the existing slab and new slab separately, but jack up from the lower part of the retainer that supports the joist timber and preload By doing so, it is possible to improve the integrity of the existing floor slab and the new floor slab in the preloading process, installation of the new floor slab, concrete placement, and curing process, and to prevent the influence on the other side as much as possible. Later, in the stage of releasing the holding of the existing floor slab and the holding of the new floor slab, a highly integrated road can be formed.

  After the new floor slab forming step, the ground cover and the railing can be formed.

  As described above, according to the present invention, since the secondary floor slab is not installed, after the concrete is placed in the formwork of the primary floor slab 12 as in the conventional example, the secondary floor slab is awaited for its strength development. There is no need for the time required for placing concrete into the formwork of the floor slab, the construction period can be shortened, and the ratio of the shortened period to the total construction period is large. As a result, full service of the bridge can be started early.

It is a perspective view of the 1st step of a prior art example. It is a perspective view of the 2nd step of a prior art example. It is a perspective view of the 3rd step of a prior art example. It is a perspective view of the 4th step of a prior art example. It is a perspective view of the 1st step of the example of the present invention. It is a perspective view of the 2nd step of the example of the present invention. It is a perspective view of the 3rd step of the example of the present invention. It is a perspective view of the 4th step of the example of the present invention. It is a top view of the example of construction of the present invention. It is the XX arrow directional view of FIG. It is a YY arrow line view of FIG. It is comparative explanatory drawing of the construction period (a) of a prior art example, and the construction period (b) of the construction example of this invention.

Next, modes for carrying out the invention will be described.
An example of the present invention will be described with reference to FIGS. However, this is only an overview.

An example is a bridge in an interchange on a highway.
The present invention relates to the widening of a bridge in which a concrete slab is arranged across abutments 6, 6 or between piers, regardless of whether they are newly installed or existing. In the illustrated example, no pier is provided, and a concrete slab is provided between the abutments 6 and 6. When there is a pier, a concrete floor slab is arranged straddling between the pier and the abutment, straddling the pier, or straddling the abutment and the pier continuously.

  In the present invention example, at least the new floor slab side of the existing floor slab 11 bent downward is sandwiched between, for example, a formwork plywood or a joist, and a load is applied upward by a jack. It has a preload process to hold. FIG. 5 shows the pre-loading step, and the existing floor slab 11 is bent downward as shown by the displacement with respect to the broken line. FIG. 6 shows a preload process state by the jack-up 5.

  Next, as shown in FIG. 7, the formwork of the new floor slab 12 for widening is made adjacent to the existing floor slab 11, and the level is held substantially the same as the holding level of the existing floor slab preloaded. To do. In this holding step, for example, an appropriate support member is used. Reference numeral 4 denotes a formwork support, which prevents the new floor slab 12 from being bent downward, and is indicated by an upward arrow.

  Preferably, there is a new floor slab forming step in which concrete is placed after reinforcing bars are placed in the formwork of the new floor slab 12 for widening after the holding step.

  Furthermore, after the said new floor slab formation process, it has the holding | maintenance release process of releasing the holding | maintenance of the existing floor slab 11 and the holding | maintenance of the new floor slab 12.

  If necessary, the ground cover and railing are formed before or during the new floor slab forming process, or preferably after the new floor slab forming process. When this is a concrete wall, it has steps of rebar, formwork assembly, concrete placement and curing.

  The construction period of the ground cover and handrail may be selected as appropriate, but in the case of a concrete wall, a new floor slab is formed, and after the ground cover and handrail is cured, the existing floor slab 11 is held and the new floor slab is placed. It is desirable to release 12 holds.

  Subsequently, a preload example of the existing floor slab 11 and a holding example of the existing floor slab 11 and the new floor slab 12 are illustrated in FIG.

In the illustrated example, an abutment 7 is provided between the abutments 6 and 6. Referring to FIGS. 9 and 10, the existing floor slab 11 is provided with a steel pipe 11b inside thereof, and the inside thereof is hollow, and a reinforcing bar (not shown) is arranged outside the steel pipe 11b. Concrete (not shown) is placed.
A new floor slab 12 is provided adjacent to the existing floor slab 11. The new floor slab 12 is also provided with a steel pipe 12b therein, a reinforcing bar (not shown) is arranged, and concrete (not shown) is placed.

Furthermore, referring also to FIG. 11, in the illustrated example, the existing floor slab 11 and the new floor slab 12 are supported by the joist members 14, 14... It is desirable to adopt a form in which a plurality is provided in the longitudinal direction of the bridge.
When supported by the joists 14, 14... Straddling the existing floor slab 11 and the new floor slab 12, the new floor slab 12 follows the vibration from the existing floor slab 11 to the new floor slab 12.

  In this case, the existing floor slab 11 can be preloaded separately, but preferably the existing floor slab 11 is preloaded together. That is, when the preloading of the existing floor slab 11 and the holding of the existing floor slab 11 and the new floor slab 12 at substantially the same level are performed together, the vibration of the existing floor slab 11 to the new floor slab 12 is caused by vibration. The plate 12 follows and vibrates. For example, the influence on the concrete placement of the new floor slab 12 especially at the young age can be suppressed as much as possible, and the occurrence of problems such as cracks can be prevented.

  In the specific example, for this purpose, on the side of the new floor slab 12, a support assembly 16 is provided on the support base 15, and the direction passes through the joists 14, 14. The newly installed floor slab 12 is supported by supporting a large drawing 17 made of a square tube or the like disposed on the support assembly 16. This support corresponds to the support work 4 described with reference to FIG.

  As shown in FIG. 10, on the existing floor slab 11 side, a threading member 19 made of a shape steel or the like disposed in the passing direction is disposed on a support base 18, and an appropriate number of jacks 20 are installed thereon, An end portion of the joist members 14, 14... Is extended below the side edge portion of the floor slab 11 on the side of the newly installed slab 12, and a large tube made of a square tube or the like disposed in the direction passing through the end portion. The existing floor slab 11 is supported by being supported by 21.

The large pull 21 is lifted by the jack 20 group, and a preload is given to the existing floor slab 11 through the joist material 14. This preloading by the jack 20 corresponds to the jack-up 5 described with reference to FIG.
The preload for the existing floor slab 11 can be, for example, to cancel the downward deflection due to the dead load when there is no support.

  As described above, the ground cover and the rail 22 can be formed before or during the new floor slab forming process, or preferably after the new floor slab 12 is formed by concrete placement and curing. The end portion of the new floor slab 12 can be supported by another supporting work 16A. Reference numeral 23 denotes a temporary wall.

  The present inventors know that according to the present invention, as shown in FIG. 12 (b), the construction period can be shortened and the road can be used quickly compared to the conventional example of FIG. 12 (a). .

  In the preloading process of the above example, only the new floor slab side of the existing floor slab is held by applying a load upward. The reason for selecting this is based on the knowledge that it is sufficient to hold only the new floor slab side of the existing floor slab with an upward load in the simulation at the planning stage. However, in the preloading process according to the present invention, not only the new floor slab side of the existing floor slab but also the opposite side can be held with an upward load.

  1, 2 ... road, 3 ... bridge, 4 ... formwork support, 5 ... jack up, 6 ... abutment, 7 ... pier, 11 ... existing floor slab, 12 ... new floor slab, 14 ... joist, 17 ... large Pull, 20 ... Jack, 21 ... Large draw, 22 ... High rail.

Claims (4)

When widening a bridge with concrete slabs straddling between abutments or piers,
A preloading process in which at least the new floor slab side of the existing floor slab is held with an upward load;
A holding step of holding the formwork of the new floor slab for widening adjacent to the existing floor slab and holding the level thereof substantially the same as the holding level of the existing floor slab in the preloading step;
A new floor slab forming process in which concrete is placed in the formwork of the new floor slab for widening together with or after the holding process;
A holding release step for releasing the holding of the existing floor slab and the holding of the new floor slab after the new floor slab forming step;
A bridge widening method characterized by comprising:   The bridge widening method according to claim 1, wherein the bridge is widened by a joist straddling the existing floor slab and the new floor slab, and there are a plurality of support portions in the longitudinal direction of the bridge. While supporting by the joist straddling the existing floor slab and the newly installed floor slab, there are a plurality of support portions in the longitudinal direction of the bridge,
The bridge widening according to claim 1, wherein in a preloading step of holding at least a new floor slab side of an existing floor slab with an upward load, jacking up is performed from below a retaining material for supporting a plurality of joists. Construction method.   The bridge widening method according to claim 1, wherein a ground cover and a rail are formed after the new floor slab forming step.

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