JP7319887B2 - Bridge pier construction method - Google Patents

Description

The present invention relates to a bridge pier construction method.

BACKGROUND ART Conventionally, a method of constructing a bridge pier by closing off a water area of a river is known (see, for example, Patent Document 1). In addition, in the construction of this type of bridge, the bridge piers are mainly constructed in the sky in order to reduce the amount of dredging and reduce the impact on the environment while enabling construction throughout the year including the dry season and shortening the construction period. A method of constructing from the ground is conventionally known (see, for example, Non-Patent Documents 1 and 2). This construction method is executed as follows. First, the river is dredged during the dry season, and a steel pipe sheet pile well 201 as shown in FIGS. 9 and 10(a) is constructed using a pile-driving barge. The steel pipe sheet pile well 201 protrudes above the water surface 73 so as to close off the water area and forms an annular shape in plan view.

Of the steel pipe sheet pile well 201, a pair of portions 207, 207 facing in the direction perpendicular to the bridge axis (perpendicular to the paper surface of FIG. 10(a)) are provided so as to protrude further upward than the other portions. For example, the structure described above is realized by the plurality of steel pipes 203a forming the portion 207 (hereinafter referred to as "protruding portion 207") extending upward higher than the other steel pipes 203b. The other steel pipe 203b protrudes from the water surface at a height similar to that of a steel pipe in a general steel pipe sheet pile well. A reinforcing structure (not shown) that reinforces such a projecting portion 207 may be appropriately constructed.

A support beam 211 extending in the direction perpendicular to the bridge axis is bridged over the upper ends of the two projecting portions 207 , 207 . Then, on the receiving beam 211, the tip part of the erection girder 205 extending in the bridge axis direction is placed. For example, the erection girder 205 is sent out from another steel pipe sheet pile well (not shown) adjacent to the steel pipe sheet pile well 201 , and its tip reaches the steel pipe sheet pile well 201 . A raising device 212 including sandals, jacks, drive synchronous jacks, endless rollers, etc. is sandwiched between the receiving beams 211 and the construction girder 205, and the construction girder 205 is appropriately raised. Thereby, the load of the receiving beam 211 and the erection girder 205 is supported by the steel pipe sheet pile well 201 .

On the upper surface of the erection girder 205, a lifting equipment 221 and a carriage 223 that can move in the direction of the bridge axis are installed. This lifting equipment 221 is arranged at a position above the steel pipe sheet pile well 201 (for example, a position directly above the receiving beam 211).

After installation of the erection girder 205, as shown in FIG. 10(b), inside the steel pipe sheet pile well 201, underwater excavation of the riverbed is performed while internal reinforcement is carried out as necessary, and the paving stone layer 227 and the bottom concrete are formed. 229 is constructed, the inside of the steel pipe sheet pile well 201 is dried up, and the top slab concrete 231 is constructed on the bottom concrete 229 . Furthermore, a pier 233 is constructed above the top concrete 231 .

Furthermore, as shown in FIG. 11(a), a column head 241 made of cast-in-place concrete is constructed above the bridge pier 233 between the pair of projecting portions 207. As shown in FIG. After that, as shown in FIG. 11(b), a vent 243 is installed on the completed column head 241, and the load of the support beam 211 and the erection girder 205 is transferred to the vent 243. After that, both ends of the support beam 211 released from the load are removed. Thereby, the load of the receiving beam 211 and the erection girder 205 is transferred to the column head 241 and the bridge pier 233 and supported.

After that, as shown in FIG. 12( a ), the upper part of the steel pipe sheet pile well 201 is cut off at the position of the upper end of the top slab concrete 231 . Then, as shown in FIG. 12(b), the column head 241 is extended in both directions of the bridge axis. After that, wagons 245 are installed on both sides of the extended column head 241, and bridge girders are sequentially constructed by the overhang erection method. On the other hand, the erection girder 205 is sent out toward the adjacent steel pipe sheet pile well, and the above-described process is executed in the adjacent steel pipe sheet pile well. A bridge is constructed by executing the above for each steel pipe sheet pile well.

Materials and equipment used for underwater excavation, construction of the pavement layer 227, construction of the base concrete 229, dry-up, construction of the top concrete 231, and construction of the piers 233 as described above are used to construct the steel pipe sheet pile well 201 through the erection girder 205. transported inside. That is, the steel pipe sheet pile well 201 is connected to the river bank via the existing completed bridge girder and the erection girder 205 . Then, the materials and equipment are transported from the river bank into the steel pipe sheet pile well 201 through the existing bridge girders and the erected girders 205 . For example, ready-mixed concrete used for pouring concrete is supplied from the river bank to the pouring site through pipes (not shown) provided on the existing bridge girders and erected girders 205 . At this time, the carriage 223 transports the materials and equipment to the vicinity of the jig crane 221 , and the lifting equipment 221 suspends the materials and equipment inside the steel pipe sheet pile well 201 . Materials and equipment used for constructing the column head 241 as described above and constructing bridge girders by the cantilever erection method are also transported from the river bank to the required locations through the existing bridge girders and erection girders 205 .

Japanese Patent Application Laid-Open No. 2017-210840

"Materials Carrying in with Girder on Hamayu Bridge", Bridge & City Project, Bridge Compilation Committee, December 10, 2003, VOL.39 No.12, December 2003, pp.4-7

"Structure and Construction Considering Environmental Conservation at Crossing the Yoshino River", Pages 6 to 8 (Document (1)-4-2, Document (1)-5, Document (1)-6), [online] , The 5th Study Group on Environmental Conservation of the Yoshino River Crossing on the Shikoku Odan Expressway (held on April 27, 2015), [Searched on September 20, 2019], Internet (URL: https://corp. w-nexco.co.jp/newly/h27/0427/pdfs/1-02.pdf)

However, there has been a need for a method of constructing piers that is more efficient than the methods described above. An object of the present invention is to provide an efficient bridge pier construction method.

A bridge pier construction method of the present invention is a bridge pier construction method for constructing a bridge pier in a water area, comprising: a front structure construction step of constructing a front structure for constructing a foundation of the bridge pier in a water area; A girder erection process in which the erection girders are laid over the preceding structure so that they are supported by the preceding structure via temporary pillars. and a construction step, wherein the temporary pillars are installed on the front structure prior to the girder erection step using materials and equipment that are transported through an erection girder that is cantilevered to the vicinity of the front structure.

A bridge pier construction method of the present invention is a bridge pier construction method for constructing a bridge pier in a water area, comprising: a front structure construction step of constructing a front structure for constructing a foundation of the bridge pier in a water area; A temporary pillar building process for building temporary pillars in a water area, a girder erecting process for spanning the temporary pillars with erection girders, and a pier building process for building piers on the front stage structure using materials and equipment transported through the erection girders, Prepare.

The front-stage structure may have a cofferdam that closes off the water area, and the piers may be constructed inside the cofferdam in the pier construction process.

The pier construction process may include a stage installation process of providing an overhang stage that is supported by the cofferdam and projects outward from the cofferdam for temporarily placing the materials and equipment used in constructing the pier.

The pier construction process may include a unit suspension process of suspending a material/equipment unit configured by assembling materials/equipment together inside the cofferdam.

The bridge pier construction method of the present invention is a bridge pier construction method for constructing a bridge pier in a water area. a stage installation step of providing an overhang stage supported by the cofferdam and overhanging to the outside.

The bridge pier construction method of the present invention is a bridge pier construction method for constructing a bridge pier in a water area. As shown in the figure, a girder erection process for connecting the erection girder to the cofferdam, and a pier construction process for constructing the pier inside the cofferdam using materials and equipment transported through the erection girder. It may be installed in the cofferdam prior to the erection process using materials and equipment that are transported through an erection girder that is cantilevered to the vicinity of the cofferdam.

The bridge pier construction method of the present invention is a bridge pier construction method for constructing bridge piers in a water area, comprising a cofferdam construction process for constructing a cofferdam for coffering a water area, and a temporary support construction process for constructing a temporary support in a water area near the cofferdam. and a girder erection step of bridging the temporary struts with the girder, and a pier construction step of constructing the pier inside the cofferdam using materials and equipment transported through the erection girder.

According to the present invention, it is possible to provide an efficient bridge pier construction method.

It is a side view (view seen in the line of sight in the direction perpendicular to the bridge axis) sequentially showing the bridge pier construction method according to the first embodiment. It is a side view which shows sequentially the bridge pier construction method which concerns on 1st Embodiment. It is a side view which shows sequentially the bridge pier construction method which concerns on 1st Embodiment. It is a perspective view which shows sequentially the bridge pier construction method which concerns on 1st Embodiment. It is a side view which shows sequentially the bridge pier construction method which concerns on 1st Embodiment. It is a side view which shows sequentially the pier construction method which concerns on 2nd Embodiment. It is a side view which shows sequentially the pier construction method which concerns on 2nd Embodiment. It is a side view which shows sequentially the pier construction method which concerns on 2nd Embodiment. It is a perspective view which shows the conventional bridge pier construction method one by one. (a) and (b) are side views (viewed in the direction perpendicular to the bridge axis) sequentially showing a conventional bridge pier construction method. (a) and (b) are side views sequentially showing a conventional bridge pier construction method. (a) and (b) are side views sequentially showing a conventional bridge pier construction method.

An embodiment of a bridge pier construction method according to the present invention will be described in detail below with reference to the drawings.

(First embodiment)
The bridge pier construction method of this embodiment is a method of constructing bridge piers of a bridge constructed over a river mainly from the air, and includes a cofferdam process, a girder construction process, and a pier construction process, which will be described below. Hereinafter, the left side of each side view is the left bank side, and the right side is the right bank side. In the following, the construction method will be described by focusing on one of the piers, taking as an example the case where the piers are constructed sequentially from the left bank side. In addition, since each drawing may exaggerate characteristic parts, the dimensional ratio of each element on the drawing is not necessarily accurate.

[Deadline process]
The closing process is executed, for example, after the river is dredged during the dry season. As shown in Fig. 1, in the cofferdam process (pre-stage structure construction process), cofferdams are constructed to coffer off the water area of the river as the pre-stage structures for forming the foundations of the piers at the positions where the piers are planned to be constructed. be done. The cofferdam in this embodiment is a steel pipe sheet pile well 1 that closes off a water area by arranging a plurality of steel pipes 3 in a well shape. The steel pipe sheet pile well 1 includes a plurality of steel pipes 3 driven into a river bed 71 using a pile driving barge or the like and protruding upward from a water surface 73 . The steel pipes 3 are connected to each other by a predetermined joint structure, and are arranged in an annular shape (for example, an annular shape) in plan view.

[Girder erection process]
In the girder erection process, the erection girder 5 is bridged over the steel pipe sheet pile well 1 from the existing steel pipe sheet pile well 91 adjacent to the left bank side. At the stage before this girder erection process, as shown in FIG. It is supported by a steel pipe sheet pile well 91 . Alternatively, the erection girder 5 may be supported by a plurality of existing steel pipe sheet pile wells, including the steel pipe sheet pile well 91 and an existing steel pipe sheet pile well (not shown) located further on the left bank side. A lifting equipment 21 and a carrier 23 (see FIG. 4) that can travel in the direction of the bridge axis are installed on the upper surface of the erection girder 5 .

From this state, as shown in FIG. 2 , the erection girder 5 is sent out from the steel pipe sheet pile well 91 toward the right bank side and extended to the vicinity of the steel pipe sheet pile well 1 in a cantilever manner. Thereafter, a temporary support 7 having the same structure as the temporary support 97 described above is provided on the upper portion of the steel pipe sheet pile well 1 . Construction of this temporary support 7 is carried out using materials and equipment 9 transported from the left bank through the erection girder 5 . In addition, the "materials and equipment" in this specification includes, for example, construction materials such as reinforcing bars, steel frames, PC steel materials, ready-mixed concrete, and construction materials such as formwork and temporary scaffolding. For example, if there is a completed existing bridge girder (not shown) extending from the left bank, the materials and equipment 9 as described above are transported through the existing bridge girder and the construction girder 5 . For example, ready-mixed concrete is supplied from the left bank to the casting site through a pipe (not shown) provided on the existing bridge girder and the erected girder 5 .

As also shown in FIG. 4 , the temporary supports 7 are formed one by one at the upper ends of the steel pipe sheet pile wells 1 facing each other in the direction perpendicular to the bridge axis. A support beam 11 extending in the direction perpendicular to the bridge axis is bridged over the upper ends of the pair of temporary supports 7 . The pair of temporary pillars 7 are provided at positions and sizes that do not interfere with the stigmas 41 to be described later. Further, the temporary support 7 is provided at a height such that the support beam 11 does not interfere with the column head 41 . The temporary support 7 is joined to the upper ends of the plurality of steel pipes 3 that constitute the steel pipe sheet pile well 1 . For this joining method, various joining methods such as welding and bolting can be adopted.

After that, as shown in FIGS. 3 and 4, the tip of the erection girder 5 is supported by the receiving beam 11 and the temporary support 7, and the erection girder 5 is further sent out from the steel pipe sheet pile well 91 toward the right bank side. be Finally, the tip of the erection girder 5 that has been sent out is sent out to a position that crosses the vertical upper part of the steel pipe sheet pile well 1 . A lifting device 12 including a sander, a jack, a drive synchronous jack, an endless roller, etc. is inserted between the erection girder 5 and the support beam 11 to adjust the vertical position of the construction girder 5 . The erection girder 5 is supported by the steel pipe sheet pile well 1 via the temporary support 7 and supported by the steel pipe sheet pile well 91 via the temporary support 97 . That is, the erection girder 5 is bridged from the steel pipe sheet pile well 91 to the steel pipe sheet pile well 1 , and the construction girder 5 is supported by at least the steel pipe sheet pile well 1 and the steel pipe sheet pile well 91 . At this time, for example, the length of the erection girder 5 is at least two spans, and the erection girder 5 is formed by three steel pipe sheet pile wells including a steel pipe sheet pile well (not shown) adjacent to the steel pipe sheet pile well 91 on the left bank side. may be supported.

[Bridge construction process]
In the pier construction process, as shown in FIG. 4, an overhang stage 13 horizontally overhanging from the outer edge of the steel pipe sheet pile well 1 above the water surface 73 is provided (stage installation process). The overhang stage 13 has, for example, an annular plate shape centered on the steel pipe sheet pile well 1 , is supported by the steel pipe sheet pile well 1 , and exists over the entire circumference of the steel pipe sheet pile well 1 . Further, on the projecting stage 13, a carriage 15 capable of running on the projecting stage 13 and a lifting equipment 17 for loading and unloading the materials and equipment 9 on the carriage 15 are installed. An overhead crane 19 is installed on the lower surface of the support beam 11 for vertically transporting the materials and equipment 9 between the inside of the steel pipe sheet pile well 1 and the carriage 15 . Further, here, the lifting equipment 21 on the construction girder 5 is arranged at a position above the steel pipe sheet pile well 1 (for example, a position directly above the receiving beam 11).

In plan view, the overhang stage 13 is provided in a size that protrudes from the erection girder 5 in the direction perpendicular to the bridge axis. With this structure, the lifting equipment 21 vertically suspends the materials and equipment 9 on the erection girder 5 and temporarily places them on the overhanging stage 13, or vertically lifts the materials and equipment 9 on the overhanging stage 13 for erection. It can be transported on the girder 5. Here, if the overhang stage 13 does not exist and the materials and equipment 9 are transported from the erection girder 5 to the inside of the steel pipe sheet pile well 1 by the lifting equipment 21, the materials and equipment 9 suspended from the lifting equipment 21 There is a possibility that the lifting equipment 21 will need to be pulled inward toward a vertically downward position, and the safety of the work will be reduced. On the other hand, due to the existence of the projecting stage 13, the equipment 9 can be transported vertically by the lifting equipment 21, and the safety of the work can be enhanced.

The lifting equipment 17 is used to load the materials and equipment 9 temporarily placed on the overhanging stage 13 onto the carriage 15 . The carriage 15 can also move to a position vertically below the overhead crane 19 so as to protrude inward from the inner edge of the overhang stage 13 . With this structure, the overhead crane 19 can vertically lift and lower the materials and equipment 9 on the carriage 15 and transport them to the inside of the steel pipe sheet pile well 1 . In order to enable the movement of the carriage 15 as described above, a guide rail 14 for guiding the carriage 15 may be provided on the overhang stage 13 as shown in FIG. 4, for example. The guide rail 14 is provided along a plane including the upper surface of the overhang stage 13, and includes, for example, a rail 14a extending in the direction perpendicular to the bridge axis and a rail 14b extending in the bridge axis direction below the overhead crane 19. there is Both ends of the rail 14b may be supported by the inner edges of the overhanging stage 13. FIG. The carriage 15 is guided by such a guide rail 14 and can move in the direction perpendicular to the bridge axis. Axial movement is possible.

As shown in FIG. 5, after the overhang stage 13 is installed, underwater excavation of the riverbed is performed inside the steel pipe sheet pile well 1 while reinforcing the inside as necessary, and the paving stone layer 27 and the bottom concrete 29 are formed. After construction, the inside of the steel pipe sheet pile well 1 is dried up, and the top slab concrete 31 is constructed on the bottom concrete 29 . Furthermore, a pier 33 made of reinforced concrete is constructed above the top slab concrete 31 .

After that, a column head 41 made of cast-in-place concrete is constructed above the bridge pier 33 at a position between the pair of temporary pillars 7 . After the column head 41 is completed, the load of the supporting beam 11 and the erection girder 5 is transferred to the column head 41, and the upper part of the steel pipe sheet pile well 1 is cut off at the position of the upper end of the top concrete 31. Since the method of changing the load of the receiving beam 11 and the erection girder 5 is the same as the method described in FIG. 11(b), detailed description thereof will be omitted.

The bridge pier 33 is completed as described above. The foundation of the bridge pier 33 is composed of the steel pipe sheet pile well 1 remaining after the upper part is excised, and the paving stone layer 27, the bottom concrete 29, and the top concrete 31 constructed inside the steel pipe sheet pile well 1.

After the bridge pier 33 is completed in this way, the column head 41 is extended so as to protrude in both directions of the bridge axis. After that, wagons (not shown) are installed on both sides of the extended column head 41, and bridge girders are sequentially constructed by the overhang erection method. After that, the erection girder 5 is sent out toward the adjacent steel pipe sheet pile well, and the above-described steps are performed in the adjacent steel pipe sheet pile well. A bridge is constructed by executing the above for each steel pipe sheet pile well.

Underwater excavation as described above, construction of paving stone layer 27, construction of base concrete 29, dry-up, construction of top slab concrete 31, construction of bridge piers 33, construction of column heads 41, and construction of bridge girders by the overhang erection method. As a method, a known method may be adopted, and further detailed description is omitted.

The materials and equipment 9 used for underwater excavation, construction of the pavement layer 27, construction of the bottom concrete 29, dry-up, construction of the top slab concrete 31, and construction of the bridge piers 33 are carried from the left bank through the installation girder 5 to the steel pipe sheet piles. It is transported inside the well 1 . That is, the steel pipe sheet pile well 1 is connected to the left bank via the completed existing bridge girder and the erection girder 5 . The materials and equipment are transported from the river bank into the steel pipe sheet pile well 1 through the existing bridge girders and the erected girders 5 . For example, ready-mixed concrete used for concrete casting is supplied from the left bank to the casting site through a pipe (not shown) provided on the existing bridge girder and erection girder 5 . The materials and equipment 9 used for constructing the column head 41 as described above and constructing the bridge girder by the overhang erection method are also transported from the left bank through the existing bridge girder and the erection girder 5 to the required location. Further, excavated soil by underwater excavation is transported by installing a conveying device such as a belcon on the construction girder 5 .

In particular, the transportation of the materials and equipment 9 from the erection girder 5 to the inside of the steel pipe sheet pile well 1 is carried out using the above-described transport truck 23, lifting equipment 21, lifting equipment 17, transport truck 15, and overhead crane 19. be. At this time, the materials and equipment 9 transported to the vicinity of the lifting equipment 21 by the carriage 23 on the erection girder 5 are vertically suspended by the lifting equipment 21 and temporarily placed on the overhang stage 13 (temporary placement process). The materials and equipment 9 that have been temporarily placed are then loaded onto the carriage 15 by the lifting equipment 17 , and the carriage 15 moves horizontally to a position vertically below the overhead crane 19 . Then, the materials and equipment 9 on the carriage 15 are lifted by the overhead crane 19, and after the carriage 15 is evacuated onto the overhanging stage 13, the materials and equipment 9 are hung vertically downward by the overhead crane 19, and the steel pipe sheet pile well is 1 inside.

Regarding the transportation of the materials and equipment 9 to the inside of the steel pipe sheet pile well 1, the materials and equipment 9 temporarily placed on the overhanging stage 13 are assembled on the overhanging stage 13 to form a unit, and the material and equipment unit is a steel pipe It may be suspended inside the sheet pile well 1 (unit suspension process). As a specific example, a scaffolding material, which is an example of the materials and equipment 9, is assembled on the overhanging stage 13 to form a scaffolding unit, and this scaffolding unit is lifted using the lifting equipment 17, the carrier 15, and the overhead crane 19. It may be transported inside the steel pipe sheet pile well 1 .

The scaffolding used for constructing the pier 33 needs to be installed in a narrow space between the planned construction position of the pier 33 and the inner wall surface of the steel pipe sheet pile well 1 . Moreover, when assembling the scaffolding, it is necessary to work at a high place corresponding to the height of the bridge pier 33 . On the other hand, as described above, the scaffolding unit unitized in advance on the relatively safe overhanging stage 13 is conveyed inside the steel pipe sheet pile well 1, so that work in a narrow space and high place as described above can be performed. is reduced and construction hazards are reduced. In addition, the number of lifting times of materials and equipment is reduced. Such material and equipment units include scaffolding units that are assembled as described above, reinforcing bar units that are made by assembling reinforcing bars (band reinforcing bars, intermediate band reinforcing bars, etc.), outer formwork, inner formwork, and large format. A formwork unit formed by assembling formwork, and the like are conceivable. Incidentally, the material and equipment unit as described above may already be assembled on the erection girder 5 or on the left bank.

By repeatedly executing the pier construction method as described above, each pier 33 is sequentially completed toward the right bank side. In addition, on each bridge pier 33 after completion, a column head may be constructed and a bridge girder may be constructed from each column head by an overhang erection method. In the bridge pier construction method of this embodiment, the amount of dredging is reduced by constructing the piers 33 mainly from above, which reduces the impact on the environment and enables year-round construction including the dry season. The construction period will be shortened. According to the bridge pier construction method of the present embodiment, the erection girder 5 is cantilevered to the vicinity of the steel pipe sheet pile well 1 and the temporary support 7 is constructed on the steel pipe sheet pile well 1. construction can be done efficiently.

(Second embodiment)
Next, a bridge pier construction method according to the second embodiment will be described. In the description of this embodiment, the same reference numerals are given to the same or equivalent components as in the first embodiment, and duplicate descriptions are omitted. In the above-described first embodiment, the erection girder 5 is supported by the steel pipe sheet pile well 1 via the temporary support 7, whereas in this embodiment, the erection girder 5 is supported by the temporary support 37 driven into the riverbed 71. It is different in that it is supported by The bridge pier construction method of this embodiment includes a cofferdam construction process, a temporary support construction process, a girder erection process, and a pier construction process, which will be described below.

[Deadline process]
As shown in FIG. 6, in the closing process of the present embodiment, a steel pipe sheet pile well 1 is constructed in the same manner as in the closing process of the first embodiment.

[Temporary post construction process]
As shown in FIG. 6 , in the temporary support construction step, a temporary support 37 is constructed in a water area near the steel pipe sheet pile well 1 . Specifically, for example, using a pile-driving barge, the temporary supports 37 are driven into the riverbed 71 in the vicinity of the steel pipe sheet pile well 1, one each on the left bank side and the right bank side. The temporary support 37 protrudes upward from the water surface 73 to a position higher than the steel pipe sheet pile well 1 . A steel pipe similar to the steel pipe 3 constituting the steel pipe sheet pile well 1 may be employed as the temporary support 37 . In this case, the device for driving the steel pipes 3 (for example, a pile-driving barge) used in the coffering process can be used as it is as the device for driving the temporary pillars 37 in the temporary pillar construction process.

[Girder erection process]
At the stage before the girder erection process, as shown in FIG. 7, temporary struts 98 are provided on each of the left bank side and the right bank side in the vicinity of the steel pipe sheet pile well 91. The girder 5 is supported by temporary struts 98 . Alternatively, the erection girder 5 may be supported by a plurality of temporary pillars including the temporary pillar 98 and a temporary pillar near an existing steel pipe sheet pile well (not shown) arranged on the left bank side.

In the girder erection process, as shown in FIG. 7, the erection girder 5 is sent out from the temporary support 98 toward the right bank, and finally, the tip of the erection girder 5 reaches the steel pipe sheet pile well 1. It is sent out to a position crossing vertically upward, and the tip of the construction girder 5 is supported by the temporary support 37 . That is, the construction girder 5 is bridged from the temporary support 98 to the temporary support 37 , and the construction girder 5 is supported by at least the temporary support 98 and the temporary support 37 . Further, similarly to the first embodiment, between the erection girder 5 and the temporary struts 37, 98, a lifting device 39 including sandals, jacks, drive synchronous jacks, endless rollers, etc. is interposed as appropriate. The positional relationship between the erection girder 5 bridged in this manner and the steel pipe sheet pile well 1 is the same as in the first embodiment. Therefore, using the lifting equipment 21 on the erection girder 5 , it is possible to transport the materials and equipment 9 between the construction girder 5 and the overhang stage 13 .

[Bridge construction process]
As shown in FIG. 8, in the bridge pier construction process, the projecting stage 13 is constructed as in the first embodiment. Furthermore, as in the first embodiment, underwater excavation, construction of paving stone layer 27, construction of base concrete 29, dry-up, construction of top concrete 31, and construction of pier 33 are executed to complete pier 33. Further, similarly to the first embodiment, the construction of the column head 41 and the construction of the bridge girder by the overhang construction method are executed to construct the bridge girder.

As described above, the first and second embodiments of the present invention have been described, but the present invention is not limited to the above embodiments, and may be modified within the scope of not changing the gist described in each claim. good. You may use it, combining the structure of each embodiment suitably.

For example, instead of the steel pipe sheet pile well 1 in each embodiment, a steel shell caisson or a pneumatic caisson may be adopted as the front structure for constructing the foundation of the pier. In this case, instead of the closing process in each embodiment, a caisson sinking process of sinking a caisson in a water area is executed as the pre-stage structure construction process. As for the installation method of this kind of steel-shelled caisson or pneumatic caisson, a well-known method can be adopted, and further detailed explanation is omitted.

Further, the steel pipe sheet pile well 1 is not limited to an annular one in plan view, and may be, for example, a so-called oval steel pipe sheet pile well or a steel pipe sheet pile well rectangular in plan view. Further, instead of the steel pipe sheet pile well 1 in each embodiment, a cofferdam that closes off a water area by arranging a plurality of steel sheet piles in a well may be employed. In the second embodiment, two temporary supports 37 are provided for one steel pipe sheet pile well, but the number of temporary supports 37 provided for one steel pipe sheet pile well is not limited to this. , may be appropriately designed as necessary. Further, in the first embodiment, the temporary support 7 and the lifting device 12 may be provided in advance on the lower surface of the tip portion of the erection girder 5 sent out toward the steel pipe sheet pile well 1 .

Furthermore, the overhanging stage 13 is not limited to having the shape of an annular plate centered on the steel pipe sheet pile well 1. For example, it may have a rectangular shape. It may be shaped like a protruding .

DESCRIPTION OF SYMBOLS 1... Steel pipe sheet pile well (former stage structure, cofferdam), 5... Erection girder, 7, 37... Temporary support, 9... Material and equipment, 13... Overhang stage, 33... Bridge pier.

Claims (6)

A pier construction method for constructing a pier in a body of water,
a front-stage structure building step of building a front-stage structure for building a foundation of the bridge pier in the water area;
A girder erecting step of constructing an erection girder over the front-stage structure so as to be supported by the front-stage structure via temporary supports provided on the front-stage structure;
a pier construction step of constructing the pier on the front structure using materials and equipment transported through the erection girder;
The bridge pier construction method, wherein, prior to the girder erection step, the temporary pillars are provided on the front structure using materials and equipment transported through the erection girder that is cantilevered to the vicinity of the front structure. A pier construction method for constructing a pier in a body of water,
a front-stage structure building step of building a front-stage structure for building a foundation of the bridge pier in the water area;
A temporary support building step of constructing a temporary support in a water area near the front stage structure;
A girder erecting step of building an erection girder over the temporary support;
a pier construction step of constructing the pier on the front structure using materials and equipment transported through the erection girder;
The front stage structure has a cofferdam that closes off the water area,
The pier construction method, wherein in the pier construction step, the pier is constructed inside the cofferdam. The front stage structure has a cofferdam that closes off the water area,
2. The bridge pier construction method according to claim 1, wherein, in said bridge pier construction step, said pier is constructed inside said cofferdam. The pier construction step includes:
4. The bridge pier construction according to claim 2 or 3, comprising a stage installation step of providing an overhanging stage supported by said cofferdam and projecting outward from said cofferdam for temporarily placing materials and equipment used for constructing said bridge pier. Method. The pier construction step includes:
The bridge pier construction method according to any one of claims 2 to 4, further comprising a unit suspension step of suspending a material/equipment unit constructed by assembling said materials/equipment together inside said cofferdam. A pier construction method for constructing a pier in a body of water,
a coffering step of constructing cofferdams closing off the water area;
A girder erection step of installing an erection girder passing vertically above the cofferdam;
A stage installation step of providing an overhang stage of a size that is supported by the cofferdam, extends outward from the cofferdam, and protrudes from the erection girder for temporarily placing materials and equipment used for constructing the bridge pier;
A suspension step of transporting the materials and equipment through the erection girder, suspending them on the overhang stage for temporary placement, and suspending them inside the cofferdam;
A bridge pier construction method comprising:

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