JP6028984B2 - How to replace the pier - Google Patents

Description

  The present invention relates to a method of exchanging bridge piers that rebuilds existing piers that support the superstructure of bridges such as road bridges and railway bridges to new ones.

There are piers that constitute the middle part of a bridge such as a road bridge or a railway bridge.
Existing bridge piers need to be reinforced and replaced (rebuilt) in order to improve the seismic performance against aging due to aging and large earthquakes.
In general, the strength of the pier can be easily and inexpensively increased by winding a reinforcing steel plate around the outer periphery of the column portion or spraying mortar.

  On the other hand, when rebuilding piers, work must be carried out while supporting the existing superstructure, and how to secure safety and reduce construction costs is a challenge. Moreover, in the case of a main road, it is required to perform the construction in a short period with as few road closures as possible.

As a conventional replacement method, there is a method using a vent (temporary cradle). In this method, a temporary vent is first installed at a position close to the existing pier. After ensuring that the upper structure is supported by this vent, the existing pier is dismantled and removed. A new pier will be constructed at the same location as the existing pier. After supporting the superstructure with the new pier, the vent is dismantled and removed.
In addition, when the pier is composed of two single-column piers, the pier replacement method employs the following process.

FIG. 4 is an explanatory view of a conventional pier replacement method. The upper figure of each step shows a plan view below the tip of the single-column pier, and the lower figure shows a front view of the pier.
A temporary fulcrum cross beam 222 is installed below the cross beam of the upper structure 220 (step 100). A reinforcing member such as the temporary support fulcrum beam 222 is formed on the cross beam having a lower strength than the main beam supported by the existing bearing 110a to reinforce the contact point with the temporary support point.

A foundation 120 on which an overhanging pier can be installed is constructed between the piers of the pair of single-column piers 110 (step 101).
Next, the column part 140 of the overhanging pier is installed on the upper part of the foundation 120 (step 102).

The beam part 160 is installed on the upper part of the column part 140 (step 103). The beam portion 160 is set to have a length shorter than that between the pair of single-column piers 110 so that the beam unit 160 can be formed without removing the existing single-column piers 110.
The temporary fulcrum 400 that supports the load of the upper structure 220 is installed on the upper surface of the beam portion 160 (step 104). The temporary fulcrum 400 needs to be selected at a location that can support the upper structure 220 in a well-balanced manner at a location narrower than the interval between the pair of existing supports 110a when the existing support 110a is removed.

The single pillar type pier is removed (step 105). Since the distance between the fulcrum points of the pair of temporary fulcrum 400 is shorter than the fulcrum point of the pair of existing bearings, when the existing single column type pier is removed, both end portions of the upper structure 220 are lowered downward, and the upper structure 220 has a slight amount. There is a risk of distortion and load.
The pair of extension beams 200 are lifted up to the beam portion 160 by using a lifting means such as a chain block and connected to both ends of the beam portion 160 (step 106).

  On the upper surface of the extension beam 200, the jack 300 is installed outside the portion where the existing support is installed, and the upper structure 220 is jacked (step 107). The upper structure 220 is lifted until the distortion of the upper structure 220 generated when the upper structure is supported only by the temporary fulcrum 400 is eliminated.

A new support 240 of an overhanging pier is installed at the same location where the existing support was installed on the upper surface of the extension beam 200 (step 108).
When the temporary fulcrum 400 and the jack 300 are removed, the upper structure 220 can be supported by the support 240 of the overhanging pier 100, and the replacement work of the pier is completed (step 109).

  Moreover, the rebuilding method of the bridge pier disclosed in Patent Document 1 is a racket-type bridge pier rebuilding method. Two new piers are built so as to sandwich the existing pier, and the superstructure is supported by the new pier, and then the existing pier is installed. It has been removed.

JP 2008-303698 A

  However, in the replacement method using the vent, it is necessary to secure a space for installing and constructing the vent before and after the existing pier. Depending on the construction site, there is a case where a space cannot be secured and it must be installed in a road under the girder, etc., and it may be necessary to perform long-term lane regulation or traffic closure. Also, since the temporary support by the vent is used as a traffic road, the base of the vent needs to be the same size as the existing pier. Furthermore, in consideration of workability at the time of temporary foundation installation, when using a direct foundation for space saving, a foundation size larger than the foundation of the existing pier is required.

  Further, in the replacement method shown in FIG. 4, there is a risk that the upper structure may be distorted or the like while being temporarily supported at a temporary fulcrum between fulcrums than the existing bearing. Furthermore, since the temporary fulcrum supporting the load of the upper structure is separated from the jack in place of the existing bearing, there is a risk that a load such as strain is applied to the upper structure. For this reason, there is a possibility that the safety of the replacement work cannot be sufficiently ensured.

  In addition, the use of temporary fulcrum and temporary fulcrum crossbeams increases the work cost and prolongs the number of days for replacement work.

  In the rebuilding method shown in Patent Document 1, since two new piers are formed, the cost is high and the installation space must be secured.

  In addition, when a new bearing is formed at a location different from the existing bearing, it is necessary to provide a separate reinforcing part in the main girder, and the number of bearings increases from the existing one, so that the initial cost and future maintenance management Costs also increase.

  In order to solve the above-described problems of the prior art, an object of the present invention is to provide a bridge pier replacement method capable of enhancing the safety of replacement work. Another object of the present invention is to provide a pier replacement method that can reduce the construction cost.

As a first means for solving the above-mentioned problem, between the pair of single-column piers supporting the superstructure, between the foundation of the overhang-type pier and the piers of the pair of single-column piers above the foundation Forming a shorter beam portion and a pair of extended beams provided with through-holes through which the single-column pier is inserted are connected to both ends of the beam portion by lifting along the longitudinal direction of the single-column pier A step of installing an overhanging pier column in a space between the foundation and the beam portion , and a jack around the upper surface of the beam portion and the extension beam and around the existing support of the single column pier. Placing the upper structure and receiving the upper structure, cutting the single-column pier, removing from the lower portion of the single-column pier, removing the tip from the through-hole, and removing the through-hole. The overhanging pier is closed on the upper surface of the extension beam. And to provide a method of replacing piers characterized by having a step of forming a Tadashi bearing.

  As a second means for solving the above-mentioned problem, the extension beam is formed by combining a pair of halved structures divided into two in the radial direction of the through hole along the longitudinal direction of the beam portion. It is in providing the exchange method of the bridge pier characterized by this.

  As a third means for solving the above-mentioned problem, in the first or second means, the column part is made of reinforced concrete, and the beam part and the extension beam are made of steel. It is to provide a method for replacing the pier.

  According to the present invention as described above, there is no need for temporary support using a vent as in the conventional construction method, traffic regulations such as under-sparing roads can be minimized, and construction costs can be reduced. Can be planned.

  In addition, since the existing pier is removed after the new pier is installed, the temporary support period at the time of replacement can be greatly shortened, and the safety of construction under traffic service can be improved.

  In addition, by cutting and removing existing piers from below, the so-called daruma drop method can be used to reduce work at high places and improve safety, while minimizing construction space. .

  Moreover, there is no provisional receiving period by the pair of temporary fulcrums that must be structurally supported between the fulcrums narrower than the fulcrums of the pair of existing bearings, and there is no possibility of applying a load such as distortion to the upper structure. In addition, since the replacement work can be performed while supporting the load of the upper structure with the existing pier until the process of forming the extension beam of the pier, the safety of the work can be ensured without applying a load to the upper structure.

  In addition, construction costs can be reduced by omitting the temporary fulcrum, cross girder reinforcement and temporary materials as before, and the existing pier can be quickly transferred to the new pier, reducing the number of days required for pier replacement work. Can be

  According to the present invention as described above, the extension beam can be formed without removing the existing single-column pier. In addition, it is possible to safely and easily lift the extension beam to the beam portion and use the existing single-column pier.

  According to the present invention as described above, since the reinforced concrete is used for the column portion, it is strong in compressive force, can be increased in strength, and is inexpensive, so that the construction cost can be suppressed. Moreover, since steel is used for the beam portion and the extension beam, the degree of freedom of shape processing is high and the workability is good, and the number of days required for the replacement work can be shortened.

It is explanatory drawing of the exchange method of the pier of this invention. It is explanatory drawing of the overhang type pier of this embodiment. It is explanatory drawing of the extension beam of this embodiment. It is explanatory drawing of the replacement | exchange method of the conventional pier.

  Embodiments of the pier replacement method of the present invention will be described below in detail with reference to the accompanying drawings. Here, the pier replacement method according to the present invention is a method of replacing a pair of single-column piers (also referred to as cylindrical piers) that support the upper structure in the width direction into an overhang type pier (also referred to as a T-type pier). It is targeted. A pair of single-column piers are constructed at a predetermined interval, and there is a space between these piers where a new overhanging pier can be constructed.

[Overhang type pier 10]
FIG. 2 is an explanatory view of the overhang type pier of this embodiment. (1) of the figure is a plan view of the pier facing downward from the support, and (2) is a front view of the pier. As shown in the figure, the overhang type pier 10 of the present embodiment includes a column portion 14 installed on the upper portion of the foundation 12, a beam portion 16 connected to the tip of the column portion 14, and a single end connected to both ends of the beam portion 16. An extension beam 20 provided with a through-hole 18 through which a column pier (not shown) can be inserted and a support 24 that contacts the upper structure 22 on the upper surface of the extension beam 20 are mainly configured.

The foundation 12 is a lowermost structure that supports a load at the lower part of the pier and transmits the load to the ground. The column part 14 is a structure that is installed on the upper part of the foundation 12 and supports the load of the upper structure 22.
The foundation 12 and the column part 14 are made of reinforced concrete as a material. By using reinforced concrete as the material, the strength can be enhanced strongly against the compressive force, and the construction cost can be reduced because it is inexpensive.

The beam portion 16 is a structure that is installed on the upper portion of the column portion 14 and supports the load of the upper structure 22 in the width direction of the upper structure 22. The beam portion 16 of this embodiment uses steel as the material. When steel is used as the material, the degree of freedom in shape processing is high and workability is good, and the number of days required for replacement work can be shortened compared to reinforced concrete.
The beam portion 16 of the present embodiment is set to a length shorter than that between the existing pair of single-column piers (not shown). With such a configuration of the beam portion 16, it can be formed on the foundation 12 between the bridges without removing the existing pair of single-column piers.
The extension beam 20 of this embodiment extends from both ends of the beam portion 16 along the longitudinal direction of the beam portion 16 and supports the load of the upper structure 22 over the width direction of the upper structure 22 in the same manner as the beam portion 16. It is a structure. The extension beam 20 is made of steel as the material of the beam portion 16. Thereby, the freedom degree of a shape process is high and workability can be improved.

  FIG. 3 is an explanatory diagram of the extension beam of the present embodiment. (1) of the same figure is a top view, (2) is the figure seen from the front side of the single pillar type pier. When the extension beam 20 is connected to the beam portion 16, the through-hole 18 is provided at a location overlapping the single column type pier 11 in plan view. The through hole 18 is set to have a diameter larger than the diameter of the single-column pier 11 so that the single-column pier 11 can be inserted. The through-hole 18 can be easily closed using the closing member 19 shown in FIG. 2 after being connected to the beam portion 16 and installed at the mounting position. The closing member 19 can use steel in the same manner as the extension beam 20. Further, the closing member 19 can be formed by combining, for example, a plate-like lid having a diameter larger than the diameter of the through hole 18 and a cylindrical body fitted into the through hole 18. The extension beam 20 is formed by combining a first structure body 20a and a second structure body 20b which are a pair of halved structures divided into two in the radial direction of the through hole 18 along the longitudinal direction of the beam portion 16. can do. The extension beam 20 having such a structure is formed by combining the first structure 20a and the second structure 20b at the lower part of the single-column pier 11, and then using the lifting means such as a chain block to the beam portion 16, The single column type pier 11 can be safely and easily lifted along the longitudinal direction of the single column type pier 11 using the single column type pier 11 as a guide.

A new support 24 is installed on the upper surface of the extension beam 20 where the through hole 18 is closed, absorbs expansion and contraction of the upper structure 22 due to the influence of temperature change, and supports the upper structure 22 to load the upper structure 22. It is a structure that transmits to the pier.
The overhanging pier 10 of this embodiment uses steel having a high degree of freedom in the shape for the beam portion 16 and the extension beam 20, and an inexpensive RC (steel reinforced concrete) member that is strong in compressive force for the column portion 14 and the foundation 12. Used as a composite pier that combines steel and RC members.

[How to replace the pier]
FIG. 1 is an explanatory view of a method for replacing a pier according to the present invention.
A foundation 12 on which the overhang-type pier of this embodiment can be installed is constructed between the piers of the pair of single-column piers 11 (step 10).

  The beam portion 16 is temporarily assembled around the foundation 12. The temporarily assembled beam portion 16 is jacked up to a predetermined height by the lower frame 32 (step 11). Next, the extension beam 20 is temporarily assembled around the single column pier 11. The first structure 20a and the second structure 20b that constitute the extended beam 20 are a pair of halved structures that are divided in the radial direction of the through hole 18 along the longitudinal direction of the beam portion 16. The halved through-holes 18 of the first structure 20a and the second structure 20b are sandwiched between the lower portions of the single-column piers 11 and are directed from the radial direction of the single-column piers 11 toward the axis. combine. The first structure 20a and the second structure 20b are connected to each other with the single-column pier 11 inserted through the through hole 18. Then, the extension beam 20 is lifted along the longitudinal (axial) direction of the single-column pier 11 from the upper frame 34 installed on the upper surface of the beam portion 16 by using lifting means such as a chain block. After the extension beam 20 is lifted to the beam portion 16 having a predetermined height, the pair of extension beams 20 are connected to both ends of the beam portion 16. After the connection, the upper frame 34 is removed.

  The beam 16 and the extended beam 20 are jacked up using the lower frame 32 and installed at the mounting position (step 12). Since the beam portion 16 and the extension beam 20 are made of steel, and are lighter in weight and have a higher degree of freedom of shape processing and better workability than reinforced concrete, the space between the pair of single-column piers 11 is a space. However, it can be easily installed using lifting means such as a chain block without removing the single-column pier 11.

  Next, the column portion 14 of the overhanging pier is installed in the space between the foundation 12 and the beam portion 16 (step 13). Since the foundation 12 and the column part 14 of this embodiment use reinforced concrete as a material, they have a strong compressive force and increase the strength to improve the earthquake resistance.

The lower mount 32 is removed. A jack 30 is disposed on the upper surface of the beam portion 16 and the extension beam 20 and around the existing support 11a of the single-column pier 11 to jack the upper structure 22 (step 14). Since all the processes so far support the load of the upper structure 22 through the existing bearing 11a of the existing single-column pier 11, the safety of the replacement work is improved compared to the work using the conventional temporary fulcrum. Can be increased.
The lower part of the single-column pier 11 is cut and removed from the lower part of the single-column pier 11, and the existing support 11a at the tip of the single-column pier 11 is pulled out from the through hole 18 and removed (step 15). Since the load of the upper structure 22 is supported by the jack 30, no load is applied to the existing single column type pier 11. Further, since the load is received by the jack 30 arranged around the existing bearing 11a, a load such as a strain is not applied to the upper structure 22 as compared with the work using the conventional temporary fulcrum. Therefore, the existing single column type pier 11 can be easily pulled out from the through hole 18 and removed.

The through hole 18 is closed using the closing member 19 (step 16). Since the extension beam 20 is made of steel, it can be easily closed by the steel closing member 19.
A new support 24 of an overhanging pier is installed on the upper surface of the extension beam 20 (step 17). By aligning the center of the new support 24 with the center of the closed through-hole 18, it can be easily attached to the same location as the existing support 11a.
Finally, when the jack is removed, the upper structure 22 can be supported by the support 24 of the overhang type pier 10, and the pier replacement operation is completed (step 18).

  According to the pier replacement method of the present invention as described above, there is no provisional reception period by a pair of temporary fulcrums that must be structurally supported between fulcrums narrower than the conventional fulcrum of a pair of existing bearings. There is no risk that the upper structure is subjected to a load such as distortion. In addition, since the replacement work can be performed while supporting the load of the superstructure with the existing pier until the process of forming the extension beam of the overhang type pier, the safety of the work can be ensured without applying a load to the superstructure.

  In addition, construction costs can be reduced by omitting the temporary fulcrum, cross girder reinforcement and temporary materials as before, and the existing pier can be quickly transferred to the new pier, reducing the number of days required for pier replacement work. Can be

  The pier replacement method of the present invention can be applied to any pier that constitutes a bridge of any road bridge or railroad bridge that employs the construction of an overhanging pier formed between a pair of single-column piers.

10 ......... Overhang type pier, 11 ......... Single column type pier, 11a ......... Existing bearing, 12 ......... Base, 14 ...... Column, 16 ......... Beam, 18 ......... Through hole , 19 ...... Closing member, 20 ...... Extension beam, 20 a ...... First structure, 20 b ...... Second structure, 22 ...... Superstructure, 24 ...... Bearing, 30 ...... Jack, 32 ......... Lower frame, 34 ......... Upper frame, 100 ...... Overhang type pier, 110 ......... Single-column type pier, 110a ...... Existing bearing, 120 ......... Base, 140 ......... Column, 160 ......... Beam, 200 ... Extension beam, 220 ... Superstructure, 222 ... Temporary fulcrum cross beam, 240 ... Support, 300 ... Jack, 400 ... fulcrum.

Claims (3)

Forming a foundation of an overhanging pier between a pair of single-column piers that support the superstructure, and forming a beam portion shorter than the pier of the pair of single-column piers above the foundation;
A step of lifting a pair of extension beams provided with through-holes through which the single-column pier is inserted, along the longitudinal direction of the single-column pier, and connecting to both ends of the beam portion;
Installing a pillar portion of an overhanging pier in a space between the foundation and the beam portion;
Jacking the upper structure by placing a jack around the upper surface of the beam portion and the extension beam and around the existing bearing of the single-column pier;
Cutting the single-column pier, removing from the lower portion of the single-column pier, pulling the tip out from the through hole and removing it;
Closing the through hole and forming a new support for the overhanging pier on the upper surface of the extension beam;
A method of exchanging piers characterized by comprising:   2. The pier replacement according to claim 1, wherein the extension beam is formed by combining a pair of halved structures divided into two in the radial direction of the through hole along the longitudinal direction of the beam portion. Method.   The pier replacement method according to claim 1 or 2, wherein the pillar portion is made of reinforced concrete, and the beam portion and the extension beam are made of steel.

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