JP2018024982A - Reinforcement method and reinforcement structure of existing pile foundation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reinforcement method and a reinforcement structure of existing pile foundation that can reinforce an existing foundation footing without widening and that can reduce the range of earth retaining work and temporary cofferdam construction work as much as possible without the need for a large-sized heavy machine.SOLUTION: A reinforcement method of an existing pile foundation for supporting a lower structure of a bridge such as a bridge pier P1 comprises: a footing drilling step of drilling until a pile head 20 of an existing pile 2 is exposed from the top face of a footing 3 of a pile foundation; a pile upper part drilling step of drilling the upper part of the existing pile 2 with the exposed pile head 20; a reinforcement material inserting step of inserting a reinforcement material 4 for reinforcing the existing pile 2 in holes h1 and h2 drilled in the previous step; and a concrete placing step of placing concrete in the holes h1 and h2 for back-filling with the reinforcement material 4 to the top face of the footing.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a reinforcing method and a reinforcing structure of an existing pile foundation, and more particularly to a reinforcing method and a reinforcing structure of an existing pile foundation that supports a lower structure of a bridge such as a bridge pier.

  Conventionally, as the reinforcement method and structure of the existing pile foundation that supports such a substructure of the bridge, a method of widening the existing footing by adding an additional pile to the side of the existing pile, and the foundation footing of the bridge pier are washed. A construction method is known in which an underground wall is constructed on the ground around the existing footing when it is dug and exposed, and the ground is improved by mixing solidified material with the ground inside.

  For example, Patent Document 1 discloses a pile vent pier installed on the riverbed for the purpose of improving the bearing capacity and the horizontal strength during earthquakes without significantly increasing the rate of hindrance to the existing pile vent pier. By installing at least one pair of small-diameter steel pipe piles 14 in the vicinity of the upstream side and the downstream side of 12, the provisional deadline is unnecessary, and the small-diameter steel pipe piles 14 are installed both during and after construction. A method of reinforcing an existing pile vent pier in which the increase in the river volume inhibition rate due to the above is suppressed as little as possible is disclosed (claim 1 of patent document 1, paragraphs [0006] to [0023] of the specification, drawings) 1 and 6).

  In addition, Patent Document 2 describes the restoration of a floating structure in which the ground 8 around the existing footing has been scoured by the influence of water flow for the purpose of ensuring sufficient support strength without hindering the channel. In the reinforced structure, a new footing 21 is constructed in the ground 8 that has been scoured, located below the existing footing and supported by the existing pile 12, and newly installed between the new footing and the lower end of the existing pier. When the pier 22 is constructed and the new footing and the new pier are constructed, the upper ends of the existing piles and the overhanging portion of the existing footing are removed, and the cross section of the existing pier is increased in length. A repair reinforcement structure and construction method for a water structure reinforced (reinforcing portion 23) accordingly is disclosed (claim 1 of patent document 2, paragraphs [0017] to [0030] of the specification, FIG. 1 of the drawings). See Fig. 8, etc.).

  However, the existing pile vent pier reinforcement method described in Patent Document 1 and the repair structure and construction method for floating structures described in Patent Document 2 are not suitable for large-scale soils. It was necessary to perform fastening work and temporary closing work. For this reason, in a narrow girder space under a bridge where large heavy machinery cannot be used, earth retaining work and temporary cut-off work have the problem that workability is poor, the work period becomes long, and the work cost increases as a result. .

  In addition, it is necessary to perform temporary closing work to ensure a dry working space in rivers and underwater foundations. However, if the necessary depth of temporary closing cannot be secured, ground improvement must be made. There was also a problem of not becoming. In addition, water stoppage treatment in the case of temporary closing work was also a problem.

  In addition, the hard ground has not only poor workability for additional piles, but also poor workability for earth retaining work and temporary cut-off work, resulting in a longer construction period and higher construction costs.

  Moreover, in patent document 3, it has a hollow part for the purpose of reusing the existing pile irrespective of soundness, and it is inserted in the said hollow part of the pile embedded in the ground, and the said pile. A reinforcing material, a cement composition filled in the hollow portion into which the reinforcing material is inserted, and a foundation formed by burying a pile head portion of the pile, and the reinforcing material includes the hollow portion A pile foundation structure having a reinforcing part arranged to reinforce the pile and a fixing part that protrudes from the pile head and is fixed to the foundation and a construction method thereof are disclosed (Patent Document 3 claim). Item 1, paragraphs [0016] to [0030] of the specification, FIG. 1 and FIG.

  However, the pile foundation structure and construction method described in Patent Document 3 is an invention that reuses an existing pile when dismantling and removing an existing building. A pile having a hollow portion, that is, a PC pile or PHC There is a problem that it can be applied only to hollow precast concrete piles such as piles. For this reason, it could not be applied to the reinforcement method of the existing pile foundation that supports the substructure of the bridge.

JP 2009-280956 A JP 2009-114721 A JP 2014-227735 A

  Therefore, the present invention has been devised in view of the above-described problems, and the object of the present invention is to reinforce an existing foundation footing without widening, and for earth retaining work or temporary fastening work. An object of the present invention is to provide a reinforcing method and a reinforcing structure for an existing pile foundation that can reduce the range as much as possible and that do not require a large heavy machine.

  The existing pile foundation reinforcing method according to the first invention is a reinforcing method of an existing pile foundation that supports a lower structure of a bridge such as a bridge pier, and the pile head of the existing pile is exposed from the upper surface of the footing of the pile foundation. A footing drilling process that drills up to the top, a pile upper drilling process that drills the upper part of the existing pile where the pile head is exposed, and a reinforcing material that reinforces the existing pile is inserted into the hole drilled in the previous process. A reinforcing material inserting step, and a concrete placing step of placing concrete in the hole and filling the reinforcing material back to the upper surface of the footing.

  The reinforcing method for an existing pile foundation according to the second invention is characterized in that, in the first invention, a footing reinforcing bar cutting step of cutting the upper surface reinforcing bar of the footing is provided.

  The reinforcement method for an existing pile foundation according to the third invention is characterized in that in the first invention or the second invention, there is a formwork installation step of installing a bottom formwork of concrete to be placed in the concrete placement step. .

  The reinforcement structure of the existing pile foundation according to the fourth invention is a reinforcement structure of an existing pile foundation that supports a lower structure of a bridge such as a bridge pier, and includes the footing of the pile foundation and the hole drilled in the existing pile. The reinforcing material which reinforces the existing pile is inserted and reinforced.

  The reinforcing structure of an existing pile foundation according to a fifth invention is characterized in that, in the fourth invention, the existing pile is a steel pipe pile or a reinforced concrete pile.

  According to the 1st invention-the 3rd invention, since a reinforcing material is inserted in the hole drilled from the upper surface of the footing of the pile foundation, the existing foundation footing can be reinforced without widening. For this reason, the range of earth retaining work and temporary closing work can be made as small as possible. In addition, large heavy machinery is not required, and existing pile foundations can be easily reinforced even in a narrow under-girder space under a bridge with pile head restrictions.

  In particular, according to the second invention, since it has a footing rebar cutting process, it becomes easy to drill concrete in the subsequent footing drilling process and pile upper drilling process, shortening the construction period and reducing the construction cost. Can be reduced.

  In particular, according to the third aspect of the present invention, since there is a formwork installation step of installing a concrete bottom formwork, the existing pile is a hollow pile such as a steel pipe pile, and the concrete is cast only on the top of the pile Even so, the present invention can be applied, and the possibility that the soil and concrete are mixed and a newly weakly placed concrete has a weak point can be reduced.

  According to the 4th invention and the 5th invention, since the reinforcing material is inserted and reinforced by the footing of the existing pile foundation and the hole drilled in the existing pile, the existing foundation footing is reinforced without widening. be able to. For this reason, the range of earth retaining work and temporary closing work can be made as small as possible. In addition, large heavy machinery is not required, and existing pile foundations can be easily reinforced even in a narrow under-girder space under a bridge with pile head restrictions.

It is sectional drawing which shows the reinforcement structure of the existing pile foundation which concerns on embodiment of this invention. It is a top view which shows the reinforcement structure of the existing pile foundation same as the above, and has expanded and has shown the existing pile to partly reinforce. It is a flowchart which shows the reinforcement construction method of the existing pile foundation which concerns on embodiment of this invention. It is process explanatory drawing which shows the footing upper surface turning process of the reinforcement construction method of the existing pile foundation same as the above, (a) is a top view, (b) is a vertical sectional view. It is process explanatory drawing which shows the footing rebar cutting process of the reinforcement construction method of the existing pile foundation same as the above, (a) is a top view, (b) is a vertical sectional view. It is process explanatory drawing which shows the footing drilling process of the reinforcement construction method of the existing pile foundation same as the above, (a) is a top view, (b) is a vertical sectional view. It is process explanatory drawing which shows the pile top drilling process of the reinforcement construction method of the existing pile foundation same as the above, (a) is a top view, (b) is a vertical sectional view. It is process explanatory drawing which shows the form installation process of the reinforcement construction method of the existing pile foundation same as the above, (a) is a top view, (b) is a vertical sectional view. It is process explanatory drawing which shows the reinforcing material insertion process of the reinforcement construction method of the existing pile foundation same as the above, (a) is a top view, (b) is a vertical sectional view. It is process explanatory drawing which shows the footing reinforcement restoration process of the reinforcement construction method of the existing pile foundation same as the above, (a) is a top view, (b) is a vertical sectional view. It is process explanatory drawing which shows the concrete placement process of the reinforcement construction method of the existing pile foundation same as the above, (a) is a top view, (b) is a vertical sectional view.

  Hereinafter, an embodiment for carrying out the reinforcement method for an existing pile foundation according to the present invention will be described in detail with reference to the drawings.

  First, the reinforcement structure of the existing pile foundation which concerns on embodiment of this invention is demonstrated using FIG.1 and FIG.2. The reinforcement structure 1 of the existing pile foundation according to this embodiment includes six piles located in the front row and the rear row in the bridge axis direction for seismic reinforcement of the pile foundation of the pier P1 that supports the bridge girder G1 of the existing bridge. The case where the periphery of a pile head is reinforced is illustrated and demonstrated. 1 is a cross-sectional view showing a reinforcing structure of an existing pile foundation according to an embodiment of the present invention, and FIG. 2 is a plan view showing a pier under the reinforcing structure of the existing pile foundation of FIG. Only the reinforced part of the existing pile to be enlarged is shown.

  As shown in FIGS. 1 and 2, an existing pile foundation reinforcing structure 1 according to this embodiment includes an existing pile 2, an existing pile foundation footing 3 integrated with the existing pile 2, and these footings 3 and It is comprised from the reinforcing material 4 etc. which were inserted in the holes h1 and h2 drilled in the existing pile 2.

  In addition, as shown in FIG. 1, FIG. 2, the pile foundation of the pier P1 is an underwater structure under the water surface of a river, and in order to construct a dry area as a work space, the temporary cutoff steel plate S1 is installed, As a support work, the upset H1 and the cut beam H2 are assembled via the giraffe jack K1. However, in FIG. 2, since it becomes difficult to see, the upset H1 and the cut beam H2 are omitted.

  As shown in the enlarged view of FIG. 2, the existing pile 2 is an existing circular cylindrical steel pipe pile, and a plurality of circular cylindrical steel pipes are joined and integrated by welding. Of course, the existing pile 2 is not limited to a steel pipe pile, and is a prestressed concrete pile formed by centrifugal force (PC pile), a high-strength prestressed concrete pile formed by centrifugal force (PHC pile), a reinforced concrete pile made in the field, etc. It is also possible to apply the present invention.

  The footing 3 is a reinforced concrete footing having a function of supporting a pier P1 with a part of the foundation and transmitting a load to the ground or the pile foundation. As shown in FIG. 1, the footing 3 has upper and lower surface reinforcing bars 31 and 32 in which deformed steel bars are combined in a cross-beam in a plan view so as to resist bending stress. Each bar is arranged.

  And the existing pile 2 and the footing 3 are joined and integrated by the pile head concrete 21 (refer FIG. 4 etc.) cast in the upper part in the hollow part of the existing pile 2. As shown in FIG.

  As shown in FIG. 2, the reinforcing material 4 is a circular cylindrical steel pipe having a diameter smaller than that of the existing pile 2, and a plurality of circular cylindrical steel pipes are joined and integrated by welding. Of course, the reinforcing material 4 may be welded at the site of the reinforcement work, or may be welded in advance in another place. Moreover, when the length of the reinforcing material 4 is short, it is needless to say that the reinforcing material 4 may not be composed of a plurality of steel pipes but may be composed of one steel pipe such as a seamless pipe.

  In addition, this reinforcing material 4 is installed so that an upper end may be located in a position higher than the existing pile 2 in order to reinforce the joint part (pile head concrete 21) of the footing 3 and the existing pile 2.

  According to the reinforcement structure of the existing pile foundation which concerns on embodiment of this invention demonstrated above, the reinforcing material 4 is inserted and reinforced by the footing of the existing pile foundation and the hole h1, h2 drilled by the existing pile. Therefore, the existing footing 3 can be reinforced without widening. For this reason, the range of earth retaining work and temporary closing work can be made as small as possible. In addition, large heavy machinery is not required, and existing pile foundations can be easily reinforced even in a narrow under-girder space under a bridge with pile head restrictions.

  Next, the reinforcement construction method of the existing pile foundation which concerns on embodiment of this invention is demonstrated using FIGS. FIG. 3 is a flowchart showing each step of the reinforcement method for the existing pile foundation according to the present embodiment.

(Advance preparation)
In the reinforcement method for the existing pile foundation according to the present embodiment, first, as an advance preparation, the exact position of the existing pile 2 to be reinforced is determined from a design drawing or a construction drawing of the pile, and the footing 3 of the existing pile foundation is determined by surveying or the like. Marking is performed to mark the position.

(1) Footing upper surface turning step Next, in the reinforcement method for the existing pile foundation according to the present embodiment, as shown in FIGS. 3 and 4, the upper surface of the footing 3 is exposed until the upper surface reinforcing bar 31 is exposed. A footing upper surface curling process is performed in which the concrete is scraped to form a rectangular hole h1. FIG. 4 is a process explanatory view showing the footing upper surface turning process of the reinforcing method of the existing pile foundation, wherein (a) is a plan view and (b) is a vertical sectional view.

  Specifically, in this process, a concrete machine in a predetermined range near the upper surface of the footing 3 that is directly above the existing pile 2 to be reinforced is beaten with a punching machine such as a call pick hammer until the lower end of the upper reinforcing bar 31 is lifted. Then, a rectangular hole h1 is drilled. The concrete rubble that has been scraped off is taken out or used for backfilling pile foundations. Of course, the hole h1 is not limited to a rectangular shape, and may be a circular hole having a diameter larger than that of the existing pile 2. However, in view of restoration of the upper surface reinforcing bar, a rectangular hole that facilitates the joint operation in a straight line is preferable.

(2) Footing rebar cutting process Next, in the reinforcement method of the existing pile foundation concerning this embodiment, as shown in FIG. 3, FIG. 5, the footing rebar cutting process which cut | disconnects the upper surface reinforcing bar 31 of the footing 3 is performed. Drawing 5 is a process explanatory view showing the footing rebar cutting process of the reinforcement method of the existing pile foundation concerning this embodiment, (a) is a top view and (b) is a vertical sectional view.

  Specifically, in this process, a rectangular machine formed with concrete is used to secure a predetermined distance necessary for the joint in the footing rebar restoration process, which is a subsequent process, using a rotary cutting grindstone (disk sander) or the like. The top rebar 31 that has been lifted up in the previous step is cut at a position away from the shape hole h1 by a certain distance. Of course, it is also possible to melt with a gas cutter without using a rotary cutting grindstone.

  In this way, by performing this step, it becomes easy to punch and drill concrete in the footing drilling step and the pile upper hole drilling step described later. For this reason, the work time of the reinforcement construction method of the existing pile foundation which concerns on embodiment can be shortened, and a construction cost can be reduced.

(3) Footing drilling step Next, in the reinforcement method for the existing pile foundation according to the present embodiment, as shown in FIGS. 3 and 6, the pile head 20 of the existing pile 2 is exposed from the upper surface of the footing 3. A footing drilling step for drilling is performed. FIG. 6 is a process explanatory view showing a footing drilling process of the reinforcing method of the existing pile foundation according to the present embodiment, wherein (a) is a plan view and (b) is a vertical sectional view.

  Specifically, in this process, a rectangular shape formed by scraping the concrete portion of the footing 3 by using a punching machine such as a call pick hammer in the same way as the footing top face turning process and forming the footing top face turning process. The hole h1 is dug down and drilled. And if the rectangular hole h1 is dug until the pile head 20 of the existing pile 2 is exposed, this process will be complete | finished.

(4) Pile upper hole drilling step Next, in the reinforcement method for the existing pile foundation according to this embodiment, as shown in FIGS. 3 and 7, the upper portion of the existing pile 2 where the pile head 20 is exposed in the previous step is cut. Pile top drilling process to drill. Drawing 7 is a process explanatory view showing the pile upper part drilling process of the reinforcement construction method of the existing pile foundation concerning this embodiment, (a) is a top view and (b) is a vertical sectional view.

  Specifically, in this step, as shown in FIG. 7, a circular hole h2 is formed by drilling the central portion around the pile core of the existing pile 2 to be reinforced using a drilling machine such as a core cutter. Drill holes. Of course, depending on the design of the existing pile foundation, generally, the pile head concrete 21 is formed only in the upper part of the steel pipe pile (existing pile 2) in order to integrate the steel pipe pile (existing pile 2) and the footing 3. It has been cast. For this reason, in this process, it drills until it penetrates the pile head concrete 21 of the existing pile 2. The diameter of the circular hole h2 is determined according to the diameter of the reinforcing material 4 so that the reinforcing material 4 can be inserted.

(5) Formwork installation process Next, in the reinforcement method for the existing pile foundation according to the present embodiment, as shown in FIGS. 3 and 8, the formwork installation for installing the bottom formwork of concrete to be placed in the subsequent process is performed. Perform the process. Drawing 8 is a process explanatory view showing the form installation process of the reinforcement construction method of the existing pile foundation concerning this embodiment, (a) is a top view and (b) is a vertical sectional view.

  Specifically, in this step, the bottom mold 5 is placed below the circular hole h2 (pile head concrete 21) formed in the previous step so that the concrete to be placed in the subsequent step does not flow out. Install. The bottom formwork 5 is supported by hanging it on the pile head concrete 21 around the circular hole h2 or by filling the cavity in the existing pile 2 with earth or sand.

  In addition, this process is not essential, and when the thickness of the pile head concrete 21 of the existing pile 2 integrated with the footing 3 is thick and has reached the lower end of the reinforcing material 4 to be inserted, it is not necessary to perform this step. . The same applies to the case where the existing pile 2 is a reinforced concrete pile made in the field.

  However, by performing this process, the present invention can be applied even if the existing pile 2 is a hollow pile such as a steel pipe pile and concrete is cast only on the top of the pile. This is preferable because it can reduce the possibility that a weak point will be formed in the concrete to be newly placed due to mixing with concrete.

(6) Reinforcing Material Inserting Step Next, in the reinforcing method for the existing pile foundation according to the present embodiment, the reinforcing material 4 made of a circular steel pipe is formed in the existing pile 2 as shown in FIGS. A reinforcing material insertion step of inserting into the circular hole h2 is performed. FIGS. 9A and 9B are process explanatory views showing a reinforcing material insertion process of the reinforcing method of the existing pile foundation according to the present embodiment, where FIG. 9A is a plan view and FIG. 9B is a vertical sectional view.

  Specifically, in this step, a step of suspending the reinforcing material 4 made of a plurality of circular cylindrical steel pipes in the aforementioned circular hole h2, and a circular cylindrical shape constituting the reinforcing material 4 on the steel pipe The steps of stacking and welding the steel pipes are sequentially repeated to construct and install the reinforcing material 4 having a length corresponding to the structural design.

  Of course, when the space under the bridge girder G1 is wide and there is no need to weld the reinforcing material 4 separately, such as when there is no need to weld on-site, the simply completed reinforcing material 4 is placed in the circular hole h2. It goes without saying that it is only necessary to hang it down and insert it.

(7) Footing Rebar Restoration Step Next, in the reinforcement method for the existing pile foundation according to the present embodiment, as shown in FIGS. 3 and 10, the upper surface reinforcement 31 of the footing 3 cut in the previous step (footing rebar cutting step). The footing rebar restoration process to restore the Drawing 10 is a process explanatory view showing the footing reinforcement restoration process of the reinforcement method of the existing pile foundation concerning this embodiment, (a) is a top view and (b) is a vertical sectional view.

  Specifically, in this step, the upper surface reinforcing bar 31 cut in the footing reinforcing bar cutting step is recovered by joining the remaining portion of the upper surface reinforcing bar 31 protruding from the side of the rectangular hole h1 with a welded joint. Of course, it is not limited to the welded joint, and needless to say, it may be restored by using various known joints such as a lap joint, a mechanical joint, and a pressure welding joint. Here, the recovery includes reconstructing the upper surface reinforcing bar 31 using a new deformed steel bar.

(8) Concrete placing process Finally, in the reinforcement method for the existing pile foundation according to this embodiment, concrete is placed in the circular hole h2 and the rectangular hole h1 as shown in FIGS. Then, a concrete placing process is performed for filling the reinforcing material 4 back to the upper surface of the footing 3. FIG. 11 is a process explanatory view showing the concrete placing process of the reinforcing method of the existing pile foundation according to the present embodiment, where (a) is a plan view and (b) is a vertical sectional view.

  Specifically, in this process, the concrete blended according to the design standard strength is pumped with a pump car, etc., and is placed while giving vibration with a vibrator etc. so that air does not escape and a cavity is not formed, and footing The footing 3 is restored by filling the circular hole h2 and the rectangular hole h1 together with the reinforcing material 4 up to the top of 3.

  Thereafter, the concrete is cured with an appropriate curing period, whereby all the steps of the reinforcing method for the existing pile foundation according to the present embodiment are completed.

  According to the reinforcing method of the existing pile foundation according to the present embodiment described above, the reinforcing material 4 is inserted into the holes h1 and h2 drilled from the upper surface of the footing 3 of the pile foundation. 3 can be reinforced without widening. For this reason, the range of earth retaining work and temporary closing work can be made as small as possible. In addition, large heavy machinery is not required, and existing pile foundations can be easily reinforced even in a narrow under-girder space under a bridge with pile head restrictions.

  In addition, since this invention drills from the upper surface of a footing, it cannot be applied to the reinforcement of the pile directly under a bridge pier. However, the seismic reinforcement of the pile foundation is to check that the yield of the pile foundation is not reached. Moreover, the definition of the yield of a pile foundation is (1) plasticizing in all the piles. (2) One row of pile head reaction forces reaches the upper limit of indentation support force. One of them. Therefore, if the pile upper part of the pile located on the outer periphery is reinforced without reinforcing the pile just below the pier, the earthquake-proof reinforcement of the pile foundation is often OK. Therefore, the present invention can be applied to the seismic reinforcement of most pile foundations.

  As mentioned above, although the reinforcement structure and reinforcement construction method of the existing pile foundation concerning this embodiment were demonstrated in detail, all the embodiment mentioned above or illustrated showed one embodiment in implementing this invention. Therefore, the technical scope of the present invention should not be construed in a limited manner.

  In particular, the circular steel pipe is exemplified as the reinforcing material of the reinforcing structure of the existing pile foundation according to the present embodiment, but the reinforcing material according to the present invention is a shape steel such as H-shaped steel or I-shaped steel, or pile head reinforcement. Steel materials such as deformed steel bars such as streaks may be used. In short, the reinforcing material according to the present invention can reinforce a predetermined strength in seismic reinforcement, and can be used as long as it is a material having good compatibility with concrete and thermal expansion.

1: Reinforced structure of existing pile foundation 2: Existing pile (existing pile foundation)
20: Pile head h2: Circular hole (hole)
3: Footing (existing pile foundation)
31: Top bar 32: Bottom bar h1: Rectangular hole (hole)
4: Reinforcement material 5: Bottom formwork (formwork)
G1: Bridge girder P1: Bridge pier (bridge substructure)
H1: Raised H2: Cut beam K1: Kirin jack S1: Temporary cut steel plate

Claims (5)

It is a reinforcement method for existing pile foundations that support the substructure of bridges such as piers,
A footing drilling step for drilling until the pile head of the existing pile is exposed from the upper surface of the footing of the pile foundation;
Pile upper drilling process for drilling the upper part of the existing pile with the pile head exposed;
Reinforcing material insertion step of inserting the reinforcing material for reinforcing the existing pile into the hole drilled in the previous step;
A concrete placing step in which concrete is placed in the hole and the entire reinforcing material is backfilled up to the upper surface of the footing. The reinforcing method for an existing pile foundation according to claim 1, further comprising a footing rebar cutting step of cutting a top rebar of the footing. The reinforcement method for an existing pile foundation according to claim 1 or 2, further comprising a formwork installation step of installing a bottom formwork of concrete to be placed in the concrete placement step. It is a reinforcement structure of the existing pile foundation that supports the substructure of the bridge such as the pier,
A reinforcing structure for an existing pile foundation, wherein a reinforcing material for reinforcing the existing pile is inserted and reinforced in a footing of the pile foundation and a hole drilled in the existing pile. The said existing pile is a steel pipe pile, The reinforcement structure of the existing pile foundation of Claim 4 characterized by the above-mentioned.

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