JP2002235328A - Cofferdam method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cofferdam method capable of shortening a construction period and reducing a construction cost in a state hardly bringing 4 water pollution. SOLUTION: A supporting device 24 is set in the neighborhood of a connecting section between the upper end of a pier 12 and a bridge girder 13. A precast panel 20 is connected in the circumferential direction to form a circular built-up body 18a for one portion of layer, and when the formation of one portion of the layer is completed, two or more layers are built up by the same procedure, and a plurality of circular built-up bodies 18a are successively connected to each other in the vertical direction to construct a cofferdam structural body 18. A plurality of jet nozzles 32 jetting the high-pressure water are arranged to the lower end of the cofferdam structural body 18 at a predetermined interval in the circumferential direction. When the cofferdam structural body 18 supported by the supporting device 24 is constructed, it is bottomed on a footing 14, and a bridge 10 is repaired. The cofferdam structural body 18 is bottomed by jetting the high-pressure water to the bottom ground 16 through the jet nozzles 32, and a circular groove 34 capable of inserting the cofferdam structural body 18 therein is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temporary closing method, and more particularly to a temporary closing method suitable for repairing underwater structures such as repair and reinforcement.

[0002]

2. Description of the Related Art Damage such as damage and collapse of structures due to earthquakes is not limited to land-based structures, but also to underwater structures constructed on rivers and seas, such as bridge foundations and seawalls. Has been reached.

[0003] Even when such underwater structures are damaged, it is necessary to take seismic reinforcement measures in the same manner as onshore structures. When implementing seismic retrofitting for underwater structures on rivers and seas, it is necessary to remove water from the surroundings of the structure and work in a dry environment. The temporary closing method used is generally adopted.

[0004] By the way, when such a temporary closing method is carried out, the foundation of the structure to be repaired is usually buried in the underwater ground, so when installing the temporary closing structure, After excavating and discharging the bottom sediment on the upper side of the foundation,
A temporary deadline structure was installed.

[0005] However, such a conventional temporary closing method has the following technical problems.

[0006]

That is, according to the conventional temporary closing method, since the excavation and excavation of the underwater ground are performed in advance, a dredger is required, and as a result, the construction period becomes longer and the construction cost increases. Was a factor.

Further, in the conventional temporary closing method, since the entire amount of underwater soil on the foundation portion is excavated and discharged, the amount of excavated soil is increased, and the influence of water pollution accompanying excavation is also widespread.

Further, when applied to a river with a fast flow, etc., the sediment is deposited immediately after the dredging of the bottom sediment.
It was difficult to completely remove the earth and sand, which further reduced the construction period and construction cost.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems. It is an object of the present invention to reduce the construction period and the construction cost by reducing the occurrence of water pollution. An object of the present invention is to provide a temporary closing method that can be performed in a state.

[0010]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention is to provide a temporary closing structure which surrounds an outer periphery of an underwater structure such as a bridge foundation, and drains the inside of the temporary closing structure. In the temporary closing method for repairing or repairing the underwater structure, the temporary closing structure includes a plurality of precast panels that are divided along a vertical direction and a circumferential direction and that can be connected to each other. With the support device installed above the underwater structure, while supporting the plurality of precast panels, they are interconnected in the circumferential direction to form an annular assembly that surrounds the outer periphery of the underwater structure, This annular assembly is sequentially connected in the vertical direction, assembled in a multilayer shape to construct the temporary closing structure, and the lower end side of the temporary closing structure is
When landing on the base portion of the underwater structure, high-pressure water is sprayed into the underwater ground to form an annular groove into which the temporary closing structure can be inserted, and the temporary landed on the base portion is formed. One end of the cutoff structure is fixedly fixed to the base portion, and a prestressing force is introduced to a vertically extending fixing anchor to integrate the base portion and the temporary cutoff structure. .

According to the temporary closing method constructed as described above,
An annular assembly formed by connecting a plurality of precast panels in the circumferential direction, the temporary closing structure assembled by vertically stacking and connecting, when the bottom side is landed on the base part of the underwater structure, High-pressure water is sprayed into the underwater ground to form an annular groove into which the temporary closing structure can be inserted, so that the entire amount of sediment on the foundation is excavated in advance as in the conventional temporary closing method. There is no need to remove the soil, the amount of excavated soil is very small, and water pollution due to excavation hardly occurs.

In the present invention, since high-pressure water is only injected into the underwater ground to form an annular groove into which an annular assembly can be inserted. Therefore, it is possible to eliminate the cause of pressure on the construction period and the construction cost.

[0013] The support device may be constituted by a reaction girder fixed to the underwater structure and a jack installed on the reaction girder to suspend and support the precast panel.

[0014]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Figure 1
FIG. 11 to FIG. 11 show an embodiment of the temporary closing method according to the present invention. The temporary closing method shown in the figure illustrates an example in which the method is applied when performing repair work such as repair and reinforcement of the bridge 10 which is an underwater structure.

The bridge 10 includes a pier 12 and a footing 14 which is a base part integrally formed at a lower end thereof. The pier 12 has a substantially circular horizontal section, and the footing 14 has a circular planar shape, and a part of the lower end is buried in the underwater ground 16.

The temporary closing structure 18 of this embodiment is installed so as to bend around the outer periphery of the pier 12, as shown in FIG. 1
2 used to create dry environmental conditions around the perimeter.

The temporary cutoff structure 18 is a concentric structure having the same shape as the pier 12, and includes a plurality of precast panels 20 having substantially the same configuration and divided along the vertical direction and the circumferential direction of the pier 12. Are the main constituent members.

As shown in detail in FIG. 3, each precast panel 20 has a shape in which a circle is divided into four at equal angular intervals in the case of the present embodiment.
0a, a plurality of vertical beams 20b, a pair of horizontal beams 20c, and a plurality of vertical ribs 20d.

The skin plate 20a is bent in an arc shape and becomes cylindrical when the pre-cas panel 20 is connected in the circumferential direction and the vertical direction, and separates the outer peripheral surface of the temporary closing structure 18.

The vertical beams 20b are arranged at both ends in the circumferential direction of the skin plate 20a and at the center thereof, and are fixed in the vertical direction on the inner surface of the skin plate 20a. The pair of horizontal beams 20c are formed of arc-shaped flat plates, and are fixed to the vertical end surfaces of the skin plate 20a and the vertical beams 20b.

The cross beam 20c is used for the precast panel 2
When the 0s are connected in the circumferential vertical direction, they become annular and reinforce the strength of the temporary closing structure 18. In addition, this cross beam 20c is
It is not limited to a pair, and may be provided in the middle of the skin plate 20a.

Each of the cross beams 20c is formed with a through hole 20g for a fixing anchor 22, which will be described later. The vertical rib 20d is located on the inner peripheral surface side of the skin plate 20a and is extended and fixed in the vertical direction.
The strength of a is reinforced.

The vertical rib 20d is not always necessary when, for example, the thickness of the skin plate 20a is increased.

Next, the precast panel 20 having the above structure
The procedure for assembling the temporary closing structure 18 will be described with reference to FIG. When assembling the temporary closing structure 18, the precast panel 20 is manufactured in a production yard near the repair site of the bridge 10 and transported to the vicinity of the bridge 10.

On the other hand, the support device 24 is located above the bridge 10, ie, near the connection between the upper end of the pier 12 and the bridge girder 13.
Is installed. The support device 24 of the present embodiment is a reaction force girder 24
And a plurality of jacks 24b installed on the lower surface side of the reaction force girder 24a.

The jack 24b suspends and supports the precast panel 20 below the jack 24b. In addition, the jack 24b
A spacer 24c is provided at the lower end of the as required.

The four precast panels 20 transported to the vicinity of the bridge 10 are first connected in the circumferential direction so as to surround the outer periphery of the pier 12, thereby forming an annular assembly 18a for one layer. .

In forming the annular assembly 18a, FIG.
As shown in (1), a water blocking plate 26 is interposed between the vertical beams 20b of the precast panels 20 adjacent in the circumferential direction, and is tightly connected with bolts and nuts, thereby securing horizontal water blocking.

After the assembly is completed or during assembly, the annular assembly 18a is suspended and supported by the jack 24a. When the formation of one layer is completed, the second and subsequent layers are assembled according to the same procedure. Are sequentially connected in the direction.

When connecting the annular assembly 18a in the vertical direction, as shown in FIG. 5, a water blocking plate 28 is interposed between the horizontal beams 20c of the precast panel 20 which are vertically adjacent to each other, and a bolt nut To secure water-tightness in the vertical direction.

In the case of the present embodiment, the above-described steps are sequentially repeated, and the annular assemblies 18a are vertically laminated in six layers and connected to each other, whereby the temporary closing structure 18 shown in FIG. Is constructed.

At the lower end of the temporary closing structure 18 thus constructed,
As shown in FIG. 6, a water-stop rubber 30 formed in an annular shape is attached, and a plurality of jet nozzles 32 for injecting high-pressure water are arranged at predetermined intervals in a circumferential direction.

The tip of the jet nozzle 32 penetrates through the cross beam 20c of the lowermost precast panel 20 and extends below it, and the other end extends upward through the temporary closing structure 18 in the vertical direction. Have been.

For the installation of the jet nozzle 32, an insertion hole 20g provided in the cross beam 20c of each precast panel 20 can be used. As shown in FIG. 6, the lowermost horizontal beam 20c is bent so that the inside faces upward. When the temporary closing structure 18 having the above configuration whose upper end side is supported by the support device 24 is constructed, the temporary closing structure 18 is settled on the footing 14 and the bridge 10 is repaired.

The details of this step are shown in FIGS. When the temporary closing structure 18 is settled on the footing 14, as shown in FIG. 7, from the lower end of the temporary closing structure 18 suspended and supported by the support device 24 via the jet nozzle 32, Injection of high-pressure water is performed toward the underwater ground 16.

When the high-pressure water is injected, the earth and sand on the underwater floor 16 is removed, and the annular groove 3 into which the temporary closing structure 18 can be inserted.
4 are formed. In this case, the width of the annular groove 34 is slightly larger than the thickness of the temporary closing structure 18.

When the jack 24b of the supporting device 24 is extended and the temporary closing structure 18 is urged downward while forming the annular groove 34 by injection of high-pressure water, the temporary closing structure 18
Is gradually pressed into the underwater ground 16, and when the lower end thereof has landed on the upper end of the footing 14, the operation is stopped and the jet nozzle 32 is removed.

Next, as shown in FIG.
2 is installed. In this case, the fixing anchor 22 is installed so as to penetrate the temporary closing structure 18 in the vertical direction by using the insertion hole 20g of the precast panel 20.

A plurality of fixing anchors 22 are provided at predetermined intervals along the circumferential direction of the temporary closing structure 18. As shown in FIG. 11, the lower end of each anchor 22 is
It is fixed and fixed to the footing 14.

In the fixed fixing structure shown in FIG. 11, a mounting hole 36 into which the fixing anchor 22 can be inserted is formed in the footing 14, and the fixing resin 38 is filled in the hole 36, and the fixing anchor 38 is fixed. The fixing anchor 22 is fixedly fixed to the footing 14 by inserting the lower end into the mounting hole 36 and curing the resin 38.

When the fixing and fixing of the fixing anchors 22 to the footing 14 are completed, as shown in FIG. 12, a hole-in jack 40 is attached to the upper end of each fixing anchor 22 and
Prestress is introduced into the anchor 22.

When mounting the hole-in jack 40, a horizontal stiffener 42 is provided on the inner periphery of the skin plate 20a of the uppermost precast panel 20, and a support plate 44 is set on the horizontal stiffener 42 to support the hole. The hole-in jack 40 is set on the pressure plate 44.

When a prestress is introduced into each anchor 22, the waterproof rubber 30 abuts on the upper end of the footing 14 and is elastically deformed as shown in FIG. Since the water stopping property of the lower end is ensured and its shape is stabilized, the support device 24 may be removed.

In this embodiment, the supporting device 24
However, when the repair work on the bridge 10 is completed, the temporary closing structure 18 is dismantled and removed, so that even if the support device 24 is left as it is, there is no problem in the construction. If not, it can be left without being removed, and can be used when the temporary closing structure 18 is dismantled or removed.

Next, as shown in FIG.
Draining of the inside surrounded by 8 and excavation and removal of earth and sand are performed to create a dry space separated by a temporary closing structure 18 on the outer periphery of the pier 12, and thereafter, as shown in FIG. The reinforcement 46 of the pier 12 is formed and repaired.

According to the temporary closing method constructed as described above, the temporary closing structure in which the annular assembly 18a formed by connecting the plurality of precast panels 20 in the circumferential direction is stacked and connected in the vertical direction is assembled. When the bottom of the body 18 is landed on the footing 14 (base portion) of the underwater structure,
High-pressure water is sprayed into the underwater ground 16, and the temporary closing structure 1
8 is formed by forming the annular groove 34 into which the insertion can be made. Therefore, unlike the conventional temporary cutoff method, it is not necessary to excavate and discharge the entire amount of underwater soil on the foundation in advance, and the excavated soil amount is extremely small. Water pollution due to excavation hardly occurs.

Further, in this embodiment, since the high-pressure water is sprayed into the underwater ground 16 to form the annular groove 34 into which the temporary closing structure 18 can be inserted, the present invention is applied to a river where the flow is fast. In addition, there is no influence of quicksand, and it is possible to eliminate the cause of pressure on the construction period and construction cost.

In the above embodiment, the temporary closing structure 18 having a circular cross section is exemplified. However, the embodiment of the present invention is not limited to this shape.
It can also be applied to an oval shape.

The number of divisions of the precast panel 20 in the circumferential direction is not limited to four, and can be appropriately selected according to the size of the temporary closing structure 18 to be constructed.

[0050]

As described above in detail in the embodiments,
ADVANTAGE OF THE INVENTION According to the temporary closing method and the temporary closing structure according to the present invention, it is possible to shorten the construction period and reduce the construction cost in a state where the occurrence of water pollution is extremely small.

[Brief description of the drawings]

FIG. 1 is a half sectional view of an assembled state of a temporary closing structure used in a temporary closing method according to the present invention.

FIG. 2 is a top view of FIG.

FIG. 3 is a perspective view of a precast panel used in the temporary closing structure shown in FIG.

FIG. 4 is a detailed view of a circumferential connecting portion of the precast panel of FIG. 3;

FIG. 5 is an enlarged view of a portion A in FIG. 1;

FIG. 6 is an enlarged view of a lower end of the temporary closing structure of FIG. 1;

FIG. 7 is an explanatory view when the temporary closing structure of FIG. 1 is landed.

FIG. 8 is an explanatory diagram of a step performed subsequent to FIG. 7;

FIG. 9 is an explanatory diagram of a step performed subsequent to FIG. 8;

FIG. 10 is an explanatory diagram of a step performed subsequent to FIG. 9;

FIG. 11 is an enlarged view of a portion B in FIG. 1;

FIG. 12 is an enlarged view of a portion C in FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Bridge 12 Bridge pier 14 Footing 18 Temporary closing structure 20 Precast panel 20a Skin plate 20b Vertical beam 20c Horizontal beam 20d Vertical rib 22 Fixing anchor 24 Supporting device 32 Jet nozzle 34 Annular groove 40 Hole in jack

Claims (2)

[Claims] 1. An underwater structure such as a bridge foundation is bent around the outer periphery of the underwater structure with a temporary closing structure, and the inside of the temporary closing structure is drained to repair or reinforce the underwater structure. In the closing method, the temporary closing structure includes a plurality of precast panels that are vertically and circumferentially divided and that can be interconnected with each other, and a plurality of the above-described support devices installed on the water surface of the underwater structure. While supporting the precast panel, they are connected to each other in the circumferential direction to form an annular assembly that surrounds the outer periphery of the underwater structure, and the annular assemblies are sequentially connected in the vertical direction to form a multilayer structure. Assembling to construct the temporary cut-off structure, when the lower end side of the temporary cut-off structure is landed on a base portion of the underwater structure, high-pressure water is jetted into the underwater ground to form the temporary cut-off structure; To form an annular groove for body insertion The pre-stressing structure is fixed to the base portion at one end by applying a prestressing force to a fixing anchor extending vertically and the base portion and the temporary cut-off structure. A temporary closing method characterized by integrating the structure with the structure. 2. The apparatus according to claim 1, wherein the supporting device comprises a reaction girder fixed to the underwater structure, and a jack installed on the reaction girder for suspending and supporting the precast panel. Item 4. The temporary closing method according to Item 1.