KR101896403B1 - Integral bridge structure and construction method thereof - Google Patents

Abstract

The present invention relates to a monolithic bridge structure including a girder which is an upper structure and a pair of alternations which are lower structures integrally joined to the lower ends of the girders at both side ends thereof, A pair of brackets; And a pair of highly rigid approach blocks provided on the alternate rear surface of the bracket at a lower side thereof and having a trapezoidal shape that gradually decreases in height in the throttle direction at an end portion of the bracket, And a self-weight of the bracket and a load acting on the bracket are transmitted to the foundation ground through the bracket and the high-rigidity approach block, thereby eliminating the need for an enlarged foundation or foundation pile.
By means of the present invention, by including a pair of brackets and a high-rigidity approach block in an integral bridge structure in which the girder and the alternation are integrally combined, it is possible to sufficiently support the self weight of the girder, The load is dispersedly transferred to the foundation foundation, and accordingly, an expansion base or foundation pile is not required, and the stability is excellent, and the economic efficiency and the workability are improved.

Description

[0001] The present invention relates to an integral bridge structure and a construction method thereof,

The present embodiment relates to an integral bridge structure and its construction method, that is, a monolithic bridge structure in which an alternation and a bridge are integrally combined, and a construction method thereof.

In general, bridges are installed by first installing a bridge foundation, and after constructing a bridge structure, by backfilling the alternate back surface (see FIG. 1A).

In this case, loosening and collapse of the backfill material under the connecting slab, generation of pores under the connecting slab due to insufficient compaction and erosion of the backfill material, settlement of the foundation ground or bedrock, drainage due to clogging or damage of the drainage material due to soil particles And the like.

In addition, lateral displacement occurs due to excessive load, horizontal earth pressure of backfill material, unbalanced load of backfill material, lateral flow, etc. In this case, it is considered that active breakage of alternating back ground, crack and settlement of pavement structure, , Deterioration of fracture and function of the extension joint, dropout and breakage of the bridge, deformation and cracks of bridge piers, alternation of conduction and cracks, deformation and cutting of bridge foundation, and deterioration of ride quality due to poor flatness.

Particularly, the shift is caused not only by the weight of the upper structure and the load due to the vehicle, but also by the horizontal earth pressure caused by the backfill material of the alternate back surface. Therefore, it is necessary to increase the number of alternating stiffness, and the number of the bridge bases must be set to several columns in order to prevent the increase of the load of the bridges or the alternation of the loads and sliding of the bridges. The problem of deformation in shifts has been constantly occurring.

In order to solve the problems of the conventional art, a method of providing an approach block on an alternate back surface so that a horizontal earth pressure does not act alternately is used.

For example, Japanese Laid-Open Patent Application No. 2014-20168 discloses a "continuous reinforced-soil integral bridge" (Figs. 2A to 2E). This prior art discloses a bridge structure in which a plurality of alternating portions and girders disposed on a support ground are integrated with each other, a soil base as a reinforcing material disposed on the back surface of the integral bridge, soil or cement improved And a reinforcing filler formed on the back surface of the integral bridge at both ends through the soil base.

That is, in the prior art, the approach block is first applied to settle the ground, and after the settlement of the ground is completed, the bridge structure is constructed so that the horizontal earth pressure on the alternate back surface is prevented by the approach block. In the alternative, only the weight of the upper structure and the vertical load .

However, according to the above-mentioned prior art, when the alternate bridge supports the self weight and the external load of the bridge, when the foundation ground is weak, the foundation file has to be installed.

Also, even if the foundation ground is not fragile, there is a problem that the foundation pile should be installed or divided into a plurality of bridges when the ground is longer than 20 m.

Further, the difference in settlement between the bridge structure and the alternate back surface can not be completely solved, and problems such as poor flatness still exist.

Patent 1: Japanese Patent Laid-Open Publication No. 2014-20168

In order to solve the above problems, the present invention provides a single-piece bridge structure in which a girder and an alternation are integrally combined and includes a bracket and a high-rigidity approach block. By combining the high- And the load acting on them are supported by the ground through the bracket and the high-rigidity approach block, so that the expansion base and the foundation pile are not required, and no coordinate device or expansion joint is required, and the differential settlement of the alternate back surface is prevented The present invention provides a monolithic bridge structure having excellent durability and maintenance property, and a construction method thereof, which are excellent in workability and economic efficiency, excellent in vibration resistance and stability.

In addition, by forming the outer end portion in the throttle direction of the main reinforcement in a round shape and filling the inside with gravel, it is possible to maintain the shape of the high-strength approach block, prevent the main reinforcement from coming off or coming off, And a method of constructing the bridge structure.

Further, a plurality of auxiliary stiffeners are respectively provided between the main stiffeners, and the auxiliary stiffener is coupled to the girder to further reinforce the high-strength approach block at the alternate rear position where a large load acts, And a method of constructing the bridge structure.

In addition, a gravel layer is formed between the alternating and high-rigidity approach blocks, and a drain pipe is provided on the alternate inner surface at the lower part of the gravel layer, whereby the integral bridging structure that drains the inflow water flowing into the alternate back surface well, Method.

An integral bridge structure according to an example of the present invention is an integral bridge structure including a girder which is an upper structure and a pair of alternations which are lower structures integrally joined to lower surfaces of both side ends of the girder, A pair of brackets horizontally coupled to both ends thereof; And a pair of highly rigid approach blocks provided on the alternate rear surface of the bracket at a lower side thereof and having a trapezoidal shape that gradually decreases in height in the throttle direction at an end portion of the bracket, And the weight of the bracket and the load acting on the bracket are transmitted to the foundation ground through the bracket and the high-rigidity approach block, so that an enlarged foundation and foundation pile may not be required.

The high-strength approach block may be a mixture of cement and gravel.

And a plurality of main stiffeners disposed horizontally in the high-rigidity approach block over the entire area and spaced vertically from each other, wherein the plurality of main stiffeners are alternately coupled to each other, And the high-rigidity approach block is alternately engaged, whereby the entire lower surface of the high-rigidity approach block is uniformly supported on the foundation foundation.

In addition, the end portion of the main reinforcement in the throttling direction is rounded, and the rounded portion is filled with gravel to maintain the shape of the highly rigid approach block, prevent the main reinforcement from coming off, And it can be characterized by good drainage.

The wing and the high rigidity approach block may further comprise a pair of wing walls coupled to the alternate back surface and surrounding both sides of the high stiffness approach block, wherein the main stiffener is coupled to the pair of wing walls, And behave together.

The stiffener further includes a plurality of auxiliary stiffeners vertically spaced apart from each other between the main stiffeners. The auxiliary stiffeners are disposed in a belt-like shape in an alternating manner with the pair of wings, And the high rigidity approach block, the alternation and the wing wall behave together by being coupled to the girder and the pair of wing walls.

The main reinforcement may be a tough geogrid, and the auxiliary reinforcement may be geogrid.

In addition, a gravel layer is formed between the alternation and the high-rigidity approach block, and a drainpipe is provided from the lower part of the gravel layer to the alternate inner surface, whereby the infiltration water flowing into the alternate back surface can be drained well .

A method of constructing an integral bridge structure according to an example of the present invention includes: a first step of constructing the pair of highly rigid approach blocks; A second step of forming a filler layer on the back surface of the high-rigidity approach block; A third step of constructing the alternation, the girder and the bracket between the high-rigidity approach blocks; And forming a packaging layer on the upper surface of the embankment layer.

By means of the present invention, it is possible to provide an integrated bridge structure in which the girder and the alternation are integrally combined and includes a bracket and a high-rigidity approach block. By combining the high rigidity approach block and the alternation with the reinforcement, The load is supported by the bracket and the high rigidity approach block, and the ground base and the foundation pile are not needed, and no coordinate system or expansion joint is required, and the uneven settlement of the alternate back surface is prevented, and workability and economical efficiency are increased , It is possible to provide an excellent effect of excellent durability, maintenance and the like, excellent in vibration resistance and stability.

In addition, by forming the outer end portion in the throttle direction of the main reinforcement in a round shape and filling the inside with gravel, it is possible to maintain the shape of the high-strength approach block, prevent the main reinforcement from coming off or coming off, Can be provided.

Further, a plurality of auxiliary stiffeners are respectively provided between the main stiffeners, and the auxiliary stiffener is coupled to the girder to further reinforce the high-strength approach block at the alternate rear position where a large load acts, Can be provided.

Further, the gravel layer is formed between the alternation and high rigidity approach blocks, and the drain pipe is provided in the lower portion of the gravel layer toward the alternate inner surface, thereby providing the effect of well draining the inflow water flowing into the alternate back surface.

1A is a cross-sectional view showing a non-integral bridge structure constructed according to the prior art.
Fig. 1B is a view showing the load action of the bridge structure of Fig. 1A. Fig.
Figs. 2A to 2E are views of another conventional art disclosed in Japanese Laid-Open Patent Application No. 2014-20168.
3 is a cross-sectional view showing an integral bridge structure according to an example of the present invention.
Fig. 4 is a side view showing the integral bridge structure of Fig. 3; Fig.
Fig. 5 is a plan view showing the integral bridge structure of Fig. 3; Fig.
Fig. 6 is a detail view showing the integral bridge structure of Fig. 3; Fig.
Fig. 7 is a view showing a load action of the monolithic bridge structure of Fig. 3; Fig.
8A to 8E are views showing a method of constructing an integral bridge structure according to an example of the present invention.

Hereinafter, some embodiments of the present invention will be described in detail with reference to exemplary drawings. In the drawings, like reference numerals are used to refer to like elements throughout the drawings, even if they are shown in different drawings. In the following description of the embodiments of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the difference that the embodiments of the present invention are not conclusive.

In describing the components of the embodiment of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are intended to distinguish the constituent elements from other constituent elements, and the terms do not limit the nature, order or order of the constituent elements. When a component is described as being "connected", "coupled", or "connected" to another component, the component may be directly connected or connected to the other component, May be "connected "," coupled "or" connected ".

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the structure of a monolithic bridge structure according to an exemplary embodiment of the present invention will be described in detail with reference to the drawings.

3 to 6, an integral bridge structure according to an exemplary embodiment of the present invention includes a girder 10 as an upper structure, and a pair of lower structures integrally joined to lower surfaces of both side ends of the girder 10 A pair of brackets 30 and a pair of high rigidity approach blocks 40 in an integral bridge structure including an alternation 20 of the bridge 20.

The brackets 30 are integrally coupled to the girders 10 in the horizontal direction at both side ends of the girder 10 and transmit the self weight of the integral bridge structure and the external load acting thereon to the high rigidity approach block 40 do. Therefore, the structure is similar to that of a normal connecting slab but has a completely different function.

Further, the length of the bracket 30 is affected by the self weight and external load of the integral bridge structure, the span and width of the bridge, the strength and size of the high rigidity approach block 40, and the like. In general, when the span of the bridge is 45 m and the width is 24 m, the length of the bracket 30 is preferably about 3 m.

In addition, since the bracket 30 serves as a cantilever beam for transmitting the self weight and the upper load of the integral bridge structure to the high-strength approach block 40, it is desirable to sufficiently strengthen the bracket 30 in consideration of stress concentration. For example, the thickness of the bracket 30 may be increased and the reinforcing bars may be sufficiently disposed, or a hook portion may be provided between the bracket 30 and the shift 20, or a steel wire may be provided between the bracket 30 and the shift 20 .

The shift 20 of this embodiment is different in function from the normal shift. That is, since the integral bridge structure according to the present embodiment has a structure in which its own weight and external load are transmitted to the ground through the bracket 30 and the high-rigidity approach block 40, the shift 20 can control the weight of the bridge and the external load, The high rigidity approach block 40 on the rear surface of the alternate 20 is supported and protected, and the high rigidity approach block 40 is combined with the reinforcing material described later.

The reinforcing member prevents rotation of the high rigidity approach block 40 by engaging the alternation 20 and the high rigidity approach block 40. That is, the upper side of the high-strength approach block 40 is inclined toward the alternate 20 and the lower side is away from the alternate 20 due to the load acting on the upper surface of the high-strength approach block 40 from the bracket 30 , And the stiffener, particularly the stiffener disposed on the lower side, prevents this. Therefore, the high-strength approach block 40 is kept horizontal, so that a uniform reaction force acts on the high-strength approach block 40 from the ground. This serves to transmit the self weight and external load of the integral bridge structure to the foundation ground through the wide bottom surface of the high rigidity approach block 40.

In the present embodiment, the self weight and the external load of the integral bridge structure are supported by the ground on the lower side of the high rigidity approach block 40, so that the alternation 20 does not require an enlarged foundation or pile foundation, The construction period and the construction cost for the construction of the building are not required, and all structural problems due to the expansion base and the file foundation are solved.

The high rigidity approach block 40 is provided on the rear side of the alternate 20 at the lower side of the bracket 30 and acts as one integral structure and transmits the load applied from the bracket 30 to the foundation foundation.

The high rigidity approach block 40 is the first construction to be built in the integral bridge structure of the present embodiment, and its scale is very large. Therefore, when the construction of the high-strength approach block 40 and the embankment of the back surface thereof are completed, the settlement of the foundation foundation is almost completed. Therefore, even if an integral bridge structure is constructed and an external load such as a vehicle acts on the foundation bridge structure, There is almost no further settlement of < / RTI >

Further, the high-rigidity approach block 40 acts as one large-sized integral structure, so that the action of an external force such as earth pressure alternately acting from the alternate back surface in the prior art does not occur. Therefore, the scale of the shift is significantly reduced compared to the conventional shift where the earth pressure is assumed. In addition, seismic loads that may occur due to back earth pressure are also significantly reduced. Therefore, the present embodiment is economical because the back earth pressure does not act and the seismic performance is excellent, and the stability and durability are remarkably increased.

Further, since the integral bridge structure is placed on the upper side of the high-strength approach block 40 through the bracket 30, no uneven settlement of the integral bridge structure and the high-strength approach block 40 occurs at all. Therefore, in the prior art, problems such as cracks in packaging due to uneven settlement of the alternate back surface and reduction in ride comfort due to uneven elasticity do not occur at all in the present embodiment.

The high rigidity approach block 40 is formed in a trapezoidal shape in which the height gradually decreases as the distance from the end of the bracket 30 increases. The wide bottom surface of the high rigidity approach block 40 is supported on the foundation foundation. The length of the lower surface of the high-strength approach block 40 varies depending on the weight, length, height, etc. of the integral bridge structure, and is preferably 20 m or more.

The high rigidity approach block 40 may be composed of a mixture of cement and gravel, wherein the modulus of elasticity of the high rigidity approach block 40 is at least 120 MPa, and the gravel has a maximum particle size D _max = 63 mm of at least 3% .

Also, a pair of wing walls 50 may be provided on both sides of the high-rigidity approach block 40 to cover both sides. This wing wall 50 can be coupled to the back surface of the shift 20.

The high rigidity approach block 40 may be provided with a reinforcing member including a main stiffener 42 and an auxiliary stiffener 44 therein. The main reinforcement 42 is installed horizontally in the high-rigidity approach block 40 over the entire area, and a plurality of the main reinforcement 42 are vertically spaced from each other. As a result, the highly rigid approach block 40 acts as a more solid body. Thus, the unitary high rigidity approach block 40 allows the load transmitted from the bracket 30 to be evenly dispersed in the foundation foundation.

Also, a plurality of main stiffeners 42 provided inside the high-rigidity approach block 40 may be inserted into the shift 20. Thus, when the load acts on the high-rigidity approach block 40 from the bracket 30, the rotation of the high-rigidity approach block 40 is prevented, that is, the lower portion of the high rigidity approach block 40 is separated from the shift 20 The entire lower surface of the high-strength approach block 40 is uniformly supported evenly on the foundation foundation (see Fig. 7).

The primary stiffener 42 comprises a tough geogrid that integrates the high stiffness approach block 40 itself and is capable of withstanding large stresses so that the high stiffness approach block 40 can be securely coupled to the stowage 20, And a carbon fiber grid of about 3 GPa or more (grid spacing of grid is about 40 mm). The upper reinforcing material 42 may be disposed at a lower portion and an uppermost portion of the high rigidity approach block 40 so that the shape of the high rigidity approach block 40 So that the highly rigid approach block 40 is protected.

One end of the main reinforcement 42 is coupled to the bridge pier and the other end is embedded in the outer end of the high-strength approach block 40. That is, in the case of the other end, it is preferable to bend the main stiffener 42 by a predetermined length, and to bury about 0.5 m. The high stiffness approach block 40 may be prepared in advance so as not to expose the main stiffener 42 to the outside end or the high stiffness approach block 40 may be exposed to the high stiffness approach block 40 The cover layer of the highly rigid approach block 40 may be further constructed so as to cover the exposed main stiffener 42 after the step 40 is completed.

In addition, by forming the outer end of the main reinforcement 42 to be rounded, it is possible to maintain the shape of the high-strength approach block 40 and prevent the main reinforcement 42 from coming off or coming off. In addition, the inside of the rounded portion can be filled with gravel and a drain pipe can be installed to quickly and easily drain the infiltrating water. At this time, it is preferable that the drain pipe is formed of a pipe having a diameter of 200 mm or more.

When the wing wall 50 is provided on both sides of the high rigidity approach block 40, the main stiffener 42 is coupled to the wing wall 50 so that the wing wall 50 protects the high rigidity approach block 40 Rigidity approach block 40 and can be made to behave together with the high rigidity approach block 40. [

A plurality of auxiliary stiffeners 42 may be vertically spaced from each other between the main stiffeners 42. The auxiliary stiffener 42 further reinforces the high rigidity approach block 40 at the alternate (20) back position where a large load is applied.

The auxiliary stiffener 42 may be a geogrid such as HDPE (High-Density-Polyethylene) or the like, and is disposed in a belt-like shape along with the pair of wings 50 and the alternation 20. The auxiliary stiffeners 42 are preferably formed to have a width of about 3 m (the grid spacing of the grid is about 40 mm), and the vertical spacing is preferably about 0.3 m.

The auxiliary stiffener 42 may be coupled to the pair of wing walls 50 to further increase the coupling force so that the wing 50 and the high-strength approach block 40 act together.

On the other hand, a gravel layer can be formed between the alternation 20 and the high-rigidity approach block 40 so as to drain the infiltration water flowing into the backside of the alternation 20, 20 may be further provided with a drain pipe line.

It is preferable that the integral bridge structure of the present invention is applied to a case where the span is long rather than long. In addition, since the girder 10 and the alternate 20 are integrally combined with each other in addition to the above-mentioned effects, there is no need for a coordinate system, a joint, etc., so that the design and construction are simple and the stability is enhanced.

Hereinafter, a method of constructing an integral bridge structure according to an example of the present invention will be described in detail with reference to the drawings.

8A to 8E, a method for constructing an integral bridge structure according to an exemplary embodiment of the present invention includes a first step of constructing a high-strength approach block 40, a second step of forming a filler layer 60, Three steps of constructing the package 20, the girder 10 and the bracket 30, and the fourth step of forming the packaging layer. On the other hand, the construction of the integral bridge structure refers to the above description.

Referring to FIGS. 8A and 8B, step 1 of constructing the high-strength approach block 40 is a step of constructing a pair of high-rigidity approach blocks 40 on the ground to which the integrated bridge structure is to be applied. The high rigidity approach block 40 is divided into several stages from the lower side to the upper side. For example, the main stiffener 42, the cemented gravel spraying and the auxiliary stiffener 42 are alternately arranged a plurality of times, the main stiffener 42 is arranged, the cemented pebble sparging and the auxiliary stiffener 42 are arranged alternately a plurality of times Construction, and so on. In this case, the main stiffener 42 and the auxiliary stiffener 42 are partially exposed to be engaged with the shift 20 and the wing 50. Also, a cover layer is formed at the outer end of the high-strength approach block 40 so that the main reinforcement 42 covers a certain portion.

Referring to FIG. 8C, the second step of forming the embankment layer 60 is the step of forming the embankment layer 60 on the back surface of the high-strength approach block 40. That is, after the high-strength approach block 40 is constructed, the embankment layer 60 is formed on the back surface thereof. When the construction of the high-strength approach block 40 and the embankment layer 60 is completed, the settlement of the foundation foundation is almost completed.

8D, the third step of installing the alternate 20, the girder 10 and the bracket 30 is to place the alternating 20, the girder 10 and the bracket 30 between the high-rigidity approach block 40, (30). The main stiffener 42 and the auxiliary stiffener 42 exposed in the high stiffness approach block 40 are embedded in the alternation 20 during the construction of the alternation 20. A gravel layer may be formed on the back surface of the alternate 20 at the time of construction of the alternation 20 and a drain pipe connected to the inside surface of the alternation 20 at the lower end of the gravel layer may be provided. At this stage, the wings 50 can be formed on both sides of the high rigidity approach block 40. The wing wall 50 can also cause the main reinforcement 42 and the auxiliary reinforcement 42 to be embedded

Referring to FIG. 8E, step 4 of forming a packaging layer is a step of forming a packaging layer on the upper surface of the embankment layer 60. It is also clear that further construction is necessary in addition to the integral bridge structure.

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments. That is, within the scope of the present invention, all the constituent elements may be constituted or operated selectively in combination with one or more. Furthermore, the terms "comprises", "comprising", or "having" described above mean that a component can be implanted unless otherwise specifically stated, But should be construed as including other elements. All terms, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs, unless otherwise defined. Commonly used terms, such as predefined terms, should be interpreted to be consistent with the contextual meanings of the related art, and are not to be construed as ideal or overly formal, unless expressly defined to the contrary.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

10: Girder
20: Shift
30: Bracket
40: High Rigidity Approach Block
42: Main stiffener
44: auxiliary stiffener
50: Wings
60: buried layer

Claims (9)

1. An integrated bridge structure comprising a girder as an upper structure and a pair of alternations as a lower structure integrally joined to lower surfaces of both side ends of the girder,
A pair of brackets horizontally coupled to both ends of the girder; And
And a pair of highly rigid approach blocks provided on the alternate backside of the bracket and having a trapezoidal shape that gradually decreases in height in the throttling direction from the end of the bracket,
The weight of the girder, the alternation, and the bracket and loads acting thereon are transmitted to the foundation foundation through the bracket and the high-rigidity approach block,
Further comprising a plurality of main stiffeners disposed horizontally across the entire area in the high-rigidity approach block and spaced vertically from each other,
The plurality of main stiffeners are alternately coupled to each other so that the high rigidity approach block is alternately engaged so that the entire lower surface of the high rigidity approach block is evenly supported on the foundation foundation,
The end portion of the main stiffener in the throttling direction is rounded and the inside of the rounded portion is filled with gravel to maintain the shape of the highly rigid approach block and prevent the main stiffener from coming off, and,
Further comprising a pair of wings coupled to the alternating back and surrounding both sides of the highly rigid approach block,
Wherein the main stiffener is coupled to the pair of wings so that the wing wall and the high rigidity approach block act together.
The method according to claim 1,
Wherein the high rigidity approach block comprises a mixture of cement and gravel.
delete delete delete The method according to claim 1,
Further comprising a plurality of auxiliary stiffeners vertically spaced apart from each other between the main stiffeners,
Wherein the auxiliary stiffener is disposed in a belt-like shape along the pair of wings and alternately,
Wherein the auxiliary stiffener is coupled to the girder and the pair of wings so that the high stiffness approach block, the alternating and the wing walls behave together.
The method of claim 6,
Wherein the primary stiffener is a tough geogrid and the secondary stiffener is a geogrid.
The method according to claim 1,
A gravel layer is formed between the alternation and the high rigidity approach block and a drain pipe is provided from the lower part of the gravel layer to the alternate inner surface so that the infiltration water flowing into the alternate back surface can be drained well Bridge structure.
The method of any one of claims 1, 2, 6, 7 and 8,
A first step of constructing the pair of highly rigid approach blocks;
A second step of forming a filler layer on the back surface of the high-rigidity approach block;
A third step of constructing the alternation, the girder and the bracket between the high-rigidity approach blocks; And
And forming a packing layer on the upper surface of the embankment layer.

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