JP5054449B2 - Rehabilitation method of pile foundation structure - Google Patents

Description

  The present invention relates to a method for repairing a pile foundation structure for the purpose of improving the earthquake resistance of an existing structure.

  The conventional pile foundation structure is connected to the foundation beam in a rigid connection with the pile cap. When a large lateral force is applied during an earthquake, a large bending moment is applied to the pile head and the end of the foundation beam. Will occur. However, some existing structures have not been seismically designed for the foundation structure and have insufficient bending strength and shear strength. Thus, existing structures with insufficient foundation earthquake resistance may cause damage to the pile heads or foundation beams during an earthquake.

For this reason, a number of reinforcing methods have been developed in the past to increase the proof strength of existing foundation structures with insufficient earthquake resistance.
For example, Patent Literature 1 discloses a reinforcement method for increasing the proof stress by enlarging the cross section of an existing concrete pile by spraying mortar or concrete after performing bar arrangement on the head peripheral surface of the existing concrete pile. Is disclosed.

  Further, in Patent Document 2, after drilling a hole in the side of an existing foundation, using this hole, the ground just below the existing foundation and around the pile head of the existing support pile A reinforcing method for making improvements is disclosed. Thereby, the supporting force with respect to the existing foundation is enhanced, and the stress acting on the pile by the ground improvement body is reduced.

JP 10-317373 A Japanese Patent Laid-Open No. 08-296240

However, since the conventional reinforcement method is based on the reinforcement principle that enhances the yield strength against the external force, the construction becomes large and uneconomical.
For example, the above-described reinforcing method for enlarging the cross section of a pile requires time and labor for excavation, reinforcement, mortar, or concrete spraying directly under the foundation, and requires a wide variety of construction facilities. Therefore, the construction becomes large and the construction period becomes long.
In addition, the reinforcement method for improving the ground directly below the foundation described later requires a large amount of work and material costs due to the need for ground improvement over a wide area, and the cost increases due to the need for large heavy machinery. There was a problem such as that.

  The present invention has been made to solve the above-mentioned problems, and is excellent in workability and economically improving the earthquake resistance of an existing foundation structure. The problem is to propose a method.

In order to solve the above-mentioned problem, the invention according to claim 1 exposes the step of exposing the joint between the pile and the foundation member constituting the pile foundation structure in a state where the existing structure is erected. Removing the concrete in the vicinity of the joint, and rehabilitating the pile foundation structure including removing the concrete at the periphery of the pile head so that the diameter of the pile becomes narrower as it goes to the upper end of the pile. Thus, the cross-sectional area of the joint is reduced, a gap is formed in the joint, and the pile head that is rigidly joined to the foundation member is semi-rigidly joined.

  According to such a method for repairing a pile foundation structure, it is possible to easily and economically pile the concrete near the joint portion by removing the concrete corresponding to the joint portion of the foundation member or the periphery of the pile head. It becomes possible to improve the earthquake resistance of the foundation structure. In other words, by reducing the cross-sectional area of the joint between the pile head and the foundation member such as a pile cap, rotational deformation of the joint is permitted during an earthquake or the like, and as a result, the bending acting on the pile head The moment can be reduced.

Here, “semi-rigid joint” means that the joint state between the pile and the foundation member is changed between the rigid joint and the pin joint by reducing the degree of fixation of the pile head and reducing the rotational rigidity. To do. This reduces the bending moment acting on the pile head during an earthquake.
Further, the “foundation member” in the present specification is a member to which a pile is connected in a pile foundation structure, and represents, for example, a foundation slab, a pile cap, a footing, a foundation beam, and the like.

The front by removing a peripheral concrete Kikui head, by reducing the cross-sectional area of the joint, in order to semirigid bonding of the base member and the rigid該杭head has been joined, is working It is easy and the amount of waste can be reduced.

Further, the invention according to claim 2 is the method for repairing a pile foundation structure according to claim 1 , wherein the reinforcing bars disposed between the pile and the foundation member at the periphery of the joint. It is characterized by cutting.
According to such a method for rehabilitating a pile foundation structure, it is possible to reduce the tensile stress acting due to the rotational deformation of the pile head, so that the earthquake resistance of the pile foundation structure is further improved.

The invention according to claim 3 is the method for repairing a pile foundation structure according to claim 1 or 2 , wherein a reinforcing member is provided around the pile immediately below the joint with a reduced cross-sectional area. It is characterized by including the process of covering.
According to the method for repairing such a pile foundation structure, it is possible to improve the concrete strength and toughness of the joint with a reduced cross section.

  According to the method for repairing a pile foundation structure of the present invention, it is possible to improve the seismic resistance of an existing foundation structure with excellent workability and economically.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the drawings. In the description, the same reference numerals are used for the same elements, and duplicate descriptions are omitted.

<First Embodiment (Reference Embodiment) >
The method of repairing a pile foundation structure according to the first embodiment aims to improve seismic resistance of an existing building (structure) 1 supported by a pile foundation structure 2 as shown in FIG. Is what you do.
Here, FIG. 1 is an elevational view showing an outline of a structure after repair according to a preferred embodiment of the present invention. Moreover, FIG. 2 is a figure which shows the repair method of the pile foundation structure which concerns on 1st Embodiment, Comprising: (a) is a longitudinal cross-sectional view which shows the pile foundation structure before repair, (b) is before repair. A plan view of the pile viewed from above, (c) is a longitudinal sectional view showing the pile foundation structure after repair, and (d) is a plan view of the pile after repair viewed from above. Furthermore, (a)-(d) of FIG. 3 is a schematic diagram which shows each process of the repair method of the pile foundation structure which concerns on 1st Embodiment.

  As shown in FIGS. 2 (a) and 2 (c), the repair method of the pile foundation structure 2 is obtained by changing the cross-sectional area of the existing joint 20 between the pile 21 and the pile cap 22 to the removal portion 20a at the periphery of the pile head. The pile heads that are rigidly joined are made semi-rigidly joined by reducing the cross-sectional area of the pile 21 by removing.

As shown in FIG. 1, the pile foundation structure 2 includes a plurality of piles 21, 21,... And foundation beams 23 that connect these piles 21, 21,. Each pile 21 and the foundation beam 23 are connected via a pile cap 22.
This pile foundation structure 2 transmits building load etc. to the support ground layer G2 via the foundation beam 23 and the pile 21.

The pile 21 is a support pile that penetrates the soft ground layer G1 and has a lower end inserted into the support ground layer G2 having a predetermined strength for a predetermined length. Although 1st Embodiment demonstrates the case of an in-situ pile, it cannot be overemphasized that the pile 21 may be a ready-made pile.
As shown in FIGS. 2 (a) and 2 (b), the pile 21 has a circular cross section, and the main reinforcing bar R1 and the reinforcing bar R2 are arranged with a predetermined concrete cover. The pile 21 is rigidly joined to the pile cap 22 by fixing the main reinforcement R1 protruding from the upper end to the pile cap 22 in a state where the upper end surface is abutted against the pile cap 22.

The pile cap 22 is a concrete member arranged to join the pile 21 and the foundation beam 23.
A pile 21 is joined to the pile cap 22 from the lower surface, and a foundation beam 23 is joined to the side surface. Further, the pillar 24 of the building 1 is joined to the upper surface of the pile cap 22.

  In the first embodiment, as shown in FIGS. 2 (c) and 2 (d), the removal portion 20 a at the periphery of the pile head (joint portion 20) rigidly joined to the pile cap 22 is scraped off and the main reinforcement R 1 The seismic resistance of the pile foundation structure 2 is improved by cutting. Thereby, joining of the pile 21 and the pile cap 22 will be in a semi-rigid joining state, and since the rotational deformation of the pile head in the junction part 20 will be accept | permitted, it acts on a pile head and a foundation beam edge part. It becomes possible to reduce a bending moment.

Next, the repair method of the pile foundation structure which concerns on 1st Embodiment is demonstrated with reference to drawings.
Such a method for repairing a pile foundation structure includes (1) an excavation process, (2) a diameter reduction process, (3) a reinforcement process, and (4) a backfilling process.

(1) Excavation process As shown in FIGS. 3 (a) and 3 (b), the excavation process involves excavating the ground G around the pile foundation structure 2 so that the joint 20 between the pile 21 and the pile cap 22 is formed. It is a step of exposing.
Excavation around the joint 20 is performed using an excavating machine M such as a backhoe, and earth retaining work is also performed as necessary. In the first embodiment, excavation is performed using the excavating machine M, but excavation may be performed manually.

(2) Diameter reduction process The diameter reduction process is a process of scraping the periphery of the joint 20 exposed by the excavation process using a concrete cutter C as shown in FIG.
In 1st Embodiment, the diameter of the junction part 20 is reduced by scraping off the periphery of a pile head.

In the diameter reduction process, first, the support member C <b> ₁ is installed directly below the joint (pile head) 20. Then, while the concrete cutter C which is supported by the support member C ₁ is moved along the periphery of the pile head, by scraping the removal portion 20a of the pile head, the junction of the pile 21 and the pile cap 22 (Pile head) The cross-sectional area of 20 is made smaller than the cross-sectional area of the pile 21 before repair. In 1st Embodiment, the main reinforcement R1 is also cut | disconnected and removed with concrete by performing the diameter reduction of a pile head (joining part 20) to the inside of the main reinforcement R1 (refer FIG. 2).

The support member C ₁ is a concrete cutter C is supported, and a member for enabling the stable movement, are formed by combining a plurality of divided steel tube. The support member C ₁ is of course not limited to the steel pipe.

In this embodiment, the support member C _1, its upper end face, by arranging to match the lower end face of the portion to be reduced in diameter of the pile head, the support member C ₁ of pile head condensation It also functions as a ruler for diameter. That is, the cutter blade of the concrete cutter C, by moving along the upper end surface of the support member C _1, the position of the lower end of the reduced diameter portion is determined.
The outer diameter of the support member C ₁ is determined in accordance with the diameter of the blade of the reduced diameter width and concrete cutter C of the pile head (length). Thus, by moving the concrete cutter C along the outer surface of the support member C _1, it is possible to shrink due to the desired width.

(3) Reinforcing step The reinforcing step is a step of covering the periphery of the portion of the periphery of the pile head with a reinforcing member 25 in the diameter reducing step, as shown in FIGS. 2 (d) and 3 (c). .

In the first embodiment, first, the outer shell 25a is arranged so as to cover the periphery of the reduced diameter portion of the pile head (joint portion 20). Next, the gap formed between the outer shell 25a and the pile 21 is filled with a filler 25b such as mortar or concrete fed from the ground via the liquid feeding pipe P. The outer shell 25a is made of, for example, a steel pipe divided into a plurality of parts, and is formed by combining in an annular shape around the reduced diameter portion of the pile head. The outer shell 25a, in a combined state, has an inner diameter larger than the outer diameter of the reduced pile head and is smaller than the outer diameter of the pile head (pile) before being reduced in diameter. It has an outer diameter.
In the first embodiment, the reinforcing member 25 is constituted by the outer shell 25a and the filler 25b. However, the reinforcing member 25 is not limited to this, and for example, a fiber reinforced sheet or a steel plate. Other reinforcing members such as can be used. Further, the outer shell 25a is not limited to a steel pipe. Moreover, the material used as the filler 25b is not limited. Furthermore, in the first embodiment, only the reduced diameter portion of the pile head is covered with the reinforcing member 25, but the periphery of the pile 21 is covered in a form including the reduced diameter portion of the pile head. It may be a thing.

(4) Backfilling step The backfilling step is a step of backfilling the place where the reinforcement of the pile head (joining portion 20) is completed in the reinforcing step, as shown in FIG. 3 (d). When the backfilling process is completed, the repair method of the pile foundation structure is completed.

As mentioned above, according to the repair method of the pile foundation structure which concerns on 1st Embodiment, it is possible to semi-rigidly join the pile head which was rigidly joined easily and cheaply. And by making semi-rigid joining of the pile head, it becomes possible to suppress the cross-sectional force generated in the pile 21 and the foundation beam 23 so as to be below the allowable value, and the improvement of the earthquake resistance of the pile foundation structure 2 is realized. The
That is, by reducing the cross-sectional area of the pile head (joint portion 20), a gap is formed in the joint portion 20 between the pile 21 and the pile cap 22, and the pile head is allowed to rotate. As a result, the bending moment generated at the pile head and the end of the foundation beam can be reduced.

In addition, it does not require large heavy machinery or special construction equipment, and the construction period can be shortened, which is economical.
Moreover, since the waste accompanying construction is only a small amount of concrete and reinforcing bars generated by the reduced diameter of the pile head, the environmental load is small.

Moreover, since the function as the pile foundation structure 2 is maintained also during repair work, the building 1 can be used continuously.
Moreover, since it is possible to improve the earthquake resistance of the existing building 1 regardless of rebuilding, the degree of freedom of application change, extension or reconstruction is increased.

  Since the pile head reduced in diameter is reinforced by the reinforcing member 25 (outer shell 25a and filler 25b), the pile head acting as a result of rotational deformation or the like, the shearing force during an earthquake, etc. Protected against it.

<Second Embodiment>
As with the first embodiment, the method for repairing a pile foundation structure according to the second embodiment is earthquake resistant with respect to an existing building (structure) 1 supported by the pile foundation structure 2 shown in FIG. The purpose is to improve the above.
Here, FIG. 4 is a figure which shows the repair method of the pile foundation structure which concerns on 2nd Embodiment, (a) is a longitudinal cross-sectional view which shows the pile foundation structure before repair, (b) is before repair. The top view which desires the pile of (2) from above, (c) is a longitudinal cross-sectional view which shows the pile foundation structure after repair, (d) is a top view which desires the pile after repair from the top. Moreover, (a)-(d) of FIG. 5 is a schematic diagram which shows each process of the repair method of the pile foundation structure which concerns on 2nd Embodiment.

As shown in FIGS. 4A and 4C, the pile foundation structure repair method according to the second embodiment uses the cross-sectional area of the existing joint 20 of the pile 21 and the pile cap 22 as shown in FIG. By reducing the cross-sectional area, the pile heads that are rigidly joined are made semi-rigidly joined.
Here, in the second embodiment, the diameter of the joint portion 20 is reduced by forming the joint portion 20 in a tapered shape, and the reinforcing member 27 is arranged around the pile just below the joint portion 20, This is different from the method for repairing the pile foundation structure according to the first embodiment in which the diameter of the joint portion (reduced diameter portion) is uniformly reduced.

  In addition, since each structure of the pile foundation structure 2 is the same as the content shown in 1st Embodiment, detailed description is abbreviate | omitted.

  In the second embodiment, as shown in FIGS. 4C and 4D, the joint 20 is tapered by scraping the periphery of the pile head (joint 20) rigidly joined to the pile cap 22. 26 is formed. Further, the main reinforcement R1 is cut to improve the earthquake resistance of the pile foundation structure 2. Thereby, joining with the pile 21 and the pile cap 22 will be in a semi-rigid joining state, and the bending deformation which acts on a pile head and a foundation beam edge part is reduced by the rotational deformation | transformation in the pile head 20 being permitted. It becomes possible.

Next, the repair method of the pile foundation structure which concerns on 2nd Embodiment is demonstrated with reference to drawings.
Such a method for repairing a pile foundation structure includes (1) an excavation process, (2) a diameter reduction process, (3) a reinforcement process, and (4) a backfilling process.

(1) Excavation process As shown in FIGS. 5 (a) and 5 (b), the excavation process involves excavating the ground G around the pile foundation structure 2 so that the joint 20 between the pile 21 and the pile cap 22 is formed. It is a step of exposing.
Excavation around the joint 20 is performed using an excavating machine M such as a backhoe, and earth retaining work is also performed as necessary. In the second embodiment, excavation machine M is used for excavation, but excavation may be performed by human power.

(2) Diameter reduction process The diameter reduction process is a process of reducing the diameter of the joint 20 using the concrete cutter C with respect to the joint 20 exposed in the excavation process, as shown in FIG.
In 2nd Embodiment, the diameter of the junction part 20 is reduced by scraping off the periphery of a pile head.

In the diameter reduction process, first, the support member C <b> ₁ is installed directly below the joint (pile head) 20. Then, while the concrete cutter C which is supported by the support member C ₁ is moved along the periphery of the pile head, joint by cutting the pile head, the pile 21 and the pile cap 22 (pile head ) Make the cross-sectional area of 20 smaller than the cross-sectional area of the pile 21 before repair.
In 2nd Embodiment, as shown in FIG.4 (c), the taper 26 is formed by removing the pile head of the pile 21 so that the diameter of the pile 21 may become narrow as it goes to the upper end of the pile 21. FIG. Moreover, in this embodiment, the diameter of the pile head is reduced so that the outer peripheral edge of the upper end surface of the pile 21 is positioned inside the main reinforcement R1 arranged to form a circle. Disconnect.

The support member C ₁ is a concrete cutter C is supported, and a member for enabling the stable movement, are formed by combining a plurality of divided steel tube. In this embodiment, the support member C _1, its upper end face, by arranging to match the lower end face of the portion to be reduced in diameter of the pile head, the support member C ₁ of pile head condensation It also functions as a ruler for diameter.
The support member C ₁ is of course not limited to the steel pipe.

(3) Reinforcing process As shown in FIGS. 4 (c), 4 (d) and 5 (c), the reinforcing process is performed with the pile 21 directly below the taper 26 formed by scraping the periphery in the diameter reducing process. This is a step of covering the periphery with the reinforcing member 27.

In the second embodiment, first, the outer shell 27a is arranged so as to cover the periphery of the pile (pile head) 21 immediately below the joint portion 20 (taper 26). Next, the gap formed between the outer shell 27a and the pile head is filled with a filler 27b such as mortar or concrete that is pumped from the ground via the liquid feeding pipe P. In the present embodiment, a steel pipe divided into a plurality of parts is used as the outer shell 27 a, and the steel pipe is configured in an annular shape around the pile head 21.
In the second embodiment, the reinforcing member 27 is constituted by the outer shell 27a and the filler 27b. However, the reinforcing member 27 is not limited to this, and for example, a fiber reinforced sheet or a steel plate. Other reinforcing members such as can be used. The outer shell 27a is not limited to a steel pipe. Further, the taper portion 26 may be reinforced by the reinforcing member 27. Further, it is possible to replace the support member C ₁ with the reinforcing member 27 and omit the support member C ₁ .

(4) Backfilling step The backfilling step is a step of backfilling the portion where the reinforcement of the joint portion 20 has been completed in the reinforcing step, as shown in FIG. When the backfilling process is completed, the repair method of the pile foundation structure is completed.

  As mentioned above, according to the repair method of the pile foundation structure which concerns on 2nd Embodiment, the clearance gap is formed in the junction part 20 of the pile 21 and the pile cap 22 by the taper 26 being formed in the pile head. , Allow the pile head to rotate. As a result, the bending moment generated at the pile head and the end of the foundation beam can be reduced. Therefore, the pile heads that have been rigidly joined can be made semi-rigidly easily and inexpensively.

  Further, since the pile 21 is reinforced by the reinforcing member 27 directly below the joint portion 20, even when a compressive force or a shearing force is applied to the pile 21 due to rotational deformation or the like, damage to the pile 21 is prevented. Is done.

  Since the effect by the repair method of the pile foundation structure which concerns on this other 2nd Embodiment is the same as the content shown in 1st Embodiment, detailed description is abbreviate | omitted.

Next, the result of having verified the effect by the repair method of the pile foundation structure of this invention is shown.
Here, FIG. 6 is a schematic diagram showing a stress state when a lateral load is applied to the structure, where (a) is a structure having a conventional pile foundation structure, and (b) is the present invention. The structure provided with the pile foundation structure repaired by the pile foundation structure repair method is shown. Moreover, FIG. 7 is a figure which shows the pile foundation structure of the structure shown in FIG. 6, Comprising: (a) is an enlarged view of the junction part of the conventional pile foundation structure, (b) is the pile foundation structure of this invention. The enlarged view of the junction part of the pile foundation structure renovated by the repair method, (c) is a graph which shows the relationship between the bending moment and rotational deformation of the junction part shown to (a) and (b).

  As shown in FIGS. 6A and 6B, when a large lateral load Y due to an earthquake or the like acts on the building (structure) 1, stress acts on the joint 20 ′ and the pile 21.

  As shown in FIG. 6 (a), the stress M acting on the pile 21 in the pile foundation structure 2 ′ in which the pile 21 is rigidly joined to the pile cap 22 becomes maximum at the joint 20 ′ at the upper end of the pile 21. Yes. In addition, a large bending moment M3 at the end of the foundation beam acts on the joint 20 '.

  On the other hand, in the building 1 including the foundation structure 2 by semi-rigid joining, as shown in FIG. 6 (b), the stress M1 acting on the upper end of the pile 21 is the pile foundation structure before repair (see FIG. 6 (a)). In comparison with the stress M2 acting on the intermediate portion of the pile 21 by being reduced to about 70%. Further, the bending moment M3 of the end portion of the foundation beam acting on the joint portion 20 is also reduced to about 70% compared to the rigidly joined pile foundation structure (see FIG. 6A).

  As shown in FIGS. 7A and 7C, the joint 20 ′ of the pile foundation structure 2 ′ in which the pile 21 and the pile cap 22 are rigidly joined has a large resistance to rotational deformation θ due to the bending moment Ma. Therefore, as shown in FIG.7 (c), after the bending moment Ma raises rapidly, a pile head will be damaged.

  On the other hand, as shown in FIGS. 7B and 7C, the pile foundation structure 2 by semi-rigid bonding is allowed to be rotationally deformed θ, so that the bending moment Mb at the joint 20 can be suppressed. The bending moment Mb does not increase extremely. Therefore, it becomes possible to prevent the joint 20 from being damaged, and the earthquake resistance of the pile foundation structure 2 can be improved.

As mentioned above, although preferred embodiment was described about this invention, this invention is not limited to the said embodiment, A design change is possible suitably in the range which does not deviate from the meaning of this invention.
For example, in each said embodiment, although the case where repair work was performed about the pile foundation structure comprised by the support pile was demonstrated, the form of a pile is not limited, For example, a friction pile may be sufficient.

  Moreover, although the said each embodiment demonstrated the case where a pile head diameter was reduced, you may reduce the diameter of the junction part of a pile and a pile cap by shaving a pile cap (foundation member).

Moreover, in each said embodiment, although the joint part shall be reduced in diameter, a pile and a foundation member are isolate | separated by removing a pile head (joint part), and between the separated pile and a foundation member. By placing a joining member having an area smaller than the cross-sectional area of the pile, the pile heads that are rigidly joined may be semi-rigidly joined.
Such a method for rehabilitating a pile foundation structure includes an excavation process for exposing a joint portion between a pile and a foundation member constituting a pile foundation structure of an existing structure, a temporary support process for temporarily supporting the foundation member, A separation step of separating the pile and the foundation member by removing the joint portion, and a joining step of arranging a joining member having an area smaller than the cross-sectional area of the pile between the separated pile and the foundation member. ing.

Moreover, in each said embodiment, although the case where the pile was joined to the pile cap was demonstrated, for example, the pile may be joined to a foundation slab, a footing, a foundation beam, etc., and the foundation member joined to a pile Is not limited to pile caps.
Moreover, the basic form of a building is not limited to what was shown to each said embodiment, For example, a piled raft form etc. may be sufficient.

In each said embodiment, although the reinforcement member shall be installed, if the intensity | strength of a pile head is fully ensured, you may abbreviate | omit a reinforcement member.
Moreover, if the pile head can be rotationally deformed, the main bars need not be cut.

In the first embodiment, the reinforcing member having an outer diameter smaller than the pile diameter is used to reinforce the portion from which the concrete has been removed by covering the periphery of the reduced diameter joint portion. You may reinforce by filling the part from which concrete was removed with mortar, concrete, etc.
In other words, after the joint between the pile and the foundation member is exposed in the state where the existing building is built, the concrete in the vicinity of the joint is removed and the reinforcing bars arranged between the pile and the foundation member The pile head that has been rigidly joined to the foundation member may be made semi-rigidly joined by filling the portion from which the concrete has been removed with a filler such as mortar or concrete.

According to such a method for rehabilitating a pile foundation, since the reinforcing bars arranged at the joint are cut, the fixing degree of the pile head is lowered and the rotational rigidity is reduced. It becomes possible to change the state between a rigid joint and a pin joint. Moreover, since the part from which the concrete of the joint part was removed is filled with the filler, the same proof stress as that of the existing pile foundation structure is expressed with respect to the axial force.
Furthermore, you may perform the further reinforcement | strengthening by covering the outer periphery of the junction part with which the filler was filled with the outer shell.

In each of the above embodiments, the diameter of the joint is reduced. However, by removing the pile head (joint), the pile and the base member are separated, and the removed portion is filled with mortar, concrete, or the like. By filling the material, the reinforcing bars arranged between the pile and the foundation member are cut while maintaining the cross-sectional area of the joint, and the pile head rigidly joined to the pile foundation structure is cut in half. It may be rigidly joined.
Such a method for rehabilitating a pile foundation structure includes an excavation process for exposing a joint portion between a pile and a foundation member constituting a pile foundation structure of an existing structure, a temporary support process for temporarily supporting the foundation member, A separation step of separating the pile and the foundation member by removing the joint portion and a filling step of filling a filler between the separated pile and the foundation member are provided.
Furthermore, the process of covering the outer periphery of the junction part with which the filler was filled with a reinforcement member may be included.

It is an elevation view which shows the outline | summary of the structure based on suitable embodiment of this invention. It is a figure which shows the repair method of the pile foundation structure which concerns on 1st Embodiment, Comprising: (a) is a longitudinal cross-sectional view which shows the pile foundation structure before repair, (b) is a plane which wants the pile before repair from upper direction (C) is a longitudinal sectional view showing a pile foundation structure after repair, and (d) is a plan view of the pile after repair viewed from above. (A)-(d) is a schematic diagram which shows each process of the repair method of the pile foundation structure which concerns on 1st Embodiment. It is a figure which shows the repair method of the pile foundation structure which concerns on 2nd Embodiment, Comprising: (a) is a longitudinal cross-sectional view which shows the pile foundation structure before repair, (b) is a plane which wants the pile before repair from upper direction (C) is a longitudinal sectional view showing a pile foundation structure after repair, and (d) is a plan view of the pile after repair viewed from above. (A)-(d) is a schematic diagram which shows each process of the repair method of the pile foundation structure which concerns on 2nd Embodiment. It is a schematic diagram which shows the stress state at the time of the load of a horizontal direction acting on a structure, (a) is a structure provided with the conventional pile foundation structure, (b) is the repair method of the pile foundation structure of this invention. A structure with a modified pile foundation structure is shown. It is a figure which shows the pile foundation structure of the structure shown in FIG. 6, Comprising: (a) is an enlarged view of the junction part of the conventional pile foundation structure, (b) was renovated by the repair method of the pile foundation structure of this invention. The enlarged view of the junction part of a pile foundation structure, (c) is a graph which shows the relationship between the bending moment and rotational deformation of the junction part shown to (a) and (b).

Explanation of symbols

1 Building (structure)
2 Pile foundation structure 20 Joint 21 Pile 22 Pile cap (foundation member)
23 Foundation beam 25 Reinforcement member

Claims (3)

A step of exposing a joint between a pile and a foundation member constituting the pile foundation structure in a state where an existing structure is built; and
Removing the concrete in the vicinity of the exposed joint, and a method for repairing a pile foundation structure comprising:
Before by removing as the diameter of the pile is narrowed as it goes to the peripheral edge of the concrete Kikui head to the upper end of the pile, by reducing the cross-sectional area of the joint, a gap is formed the joint, the A method for repairing a pile foundation structure , characterized in that the pile head that has been rigidly joined to the foundation member is semi-rigidly joined. The method of repairing a pile foundation structure according to claim 1, wherein a reinforcing bar disposed between the pile and the foundation member is cut at a peripheral edge of the joint portion. The method for repairing a pile foundation structure according to claim 1 or 2 , further comprising a step of covering the periphery of the pile immediately below the joint with a reduced cross-sectional area with a reinforcing member.

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