JP2009007746A - Joint structure of pile head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a joint structure of a pile head which has excellent construction performance and can reduce construction cost. <P>SOLUTION: In this joint structure of the pile head, a joint 21 is interposed between the pile head 11a of a precast concrete pile 11 and a foundation 31 supported by the precast concrete pile 11. The precast concrete pile 11 is composed of a hollow steel-pipe concrete pile; the joint 21 is arranged in a hollow portion 14 of the steel-pipe concrete pile in such a manner that one end is protruded to the side of the foundation 31; and the precast concrete pile 11 and the foundation 31 are arranged in such a manner as to come into contact with each other. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pile head joint structure.

When a large horizontal force due to an earthquake or the like acts on the pile foundation, the pile head may be destroyed due to excessive stress generated in the pile head. For this reason, the pile head joint structure which relieves the stress which arises in a pile head by making a pile head into pin joint or semi-rigid and semi-fixed joint is proposed.
In recent years, a large number of ready-made concrete piles with high bearing capacity have been proposed, and a high bearing capacity can be obtained with a small pile diameter, and the number of piles used can be reduced compared to the conventional piles. Yes.
On the other hand, if the number of piles is small and the pile diameter is small, there is a problem that the pile head bending moment increases when the same seismic force is applied.

In order to solve the problem, the footing and the steel pipe pile are joined via the connecting part steel pipe, the upper end side and the lower end side of the connecting part steel pipe are respectively inserted by a predetermined length, and a gap is formed between the footing and the steel pipe pile. There has been proposed one in which both are connected in a state of providing (see, for example, Patent Document 1). In addition, a joint is provided between the foundation and the pile head, and the foundation and the pile head are separated from each other. The joint is a steel pipe, a concrete part packed in the steel pipe, and the outside of the steel pipe. There has been proposed one having a steel pipe outer side support portion which is formed around and between the foundation and the pile head and is smaller in plan view than the pile head (for example, see Patent Document 2).
JP 2002-54158 A JP 2004-263497 A

  By the way, in the joint structure of a pile head like the above-mentioned patent documents 1 and patent documents 2, a crevice is formed between a foundation and a pile, and a steel pipe (connection part steel pipe, joined part) is arranged in the crevice. This steel pipe bears all the forces of axial force, bending and shearing force. Therefore, in order to ensure the strength of the steel pipe, a large amount of steel material must be used, so that there is a problem that the weight of the steel pipe becomes very heavy and expensive. Moreover, since installation and positioning of a steel pipe must be performed using a dedicated jig, there is a problem that construction takes time.

  Then, this invention is made | formed in view of the above-mentioned situation, and provides the joining structure of the pile head which has good workability and can aim at reduction of a construction cost.

  In order to solve the above-mentioned problem, the invention described in claim 1 is a pile head in which a joint portion is interposed between a pile head of a ready-made concrete pile and a foundation supported by the ready-made concrete pile. In the joint structure, the ready-made concrete pile is configured by a hollow steel pipe concrete pile, and the joint is disposed in a hollow portion of the steel pipe concrete pile so that one end protrudes toward the foundation side. And the base are connected to each other.

By comprising in this way, since it is comprised without providing a clearance gap between a ready-made concrete pile and a foundation, axial force is directly transmitted to a ready-made concrete pile. In addition, since no anchoring bars are provided between the ready-made concrete pile and the foundation, the bending moment is transmitted from the foundation to the ready-made concrete pile through the joint. Therefore, since it is only necessary for the joint portion to have a necessary bending strength, the strength of the joint portion can be reduced. As a result, since the weight of the joint portion can be reduced, the workability can be improved and the construction cost can be reduced.
Moreover, by joining the ready-made concrete pile and the foundation via the joint portion, the rigidity of the pile head joint portion is lowered to be in a semi-rigid joint state, and the bending moment acting on the pile head portion is reduced. As a result, the pile head will not be damaged by a large earthquake. Furthermore, along with the reduction of the pile head stress, the pile body cross section and the foundation frame cross section are reduced, the amount of excavated sand is reduced, and the construction cost and the construction period can be shortened.

  According to a second aspect of the present invention, the joint portion is composed of a reinforced concrete column that closes the hollow portion, and an anchor bar of the reinforced concrete column extends from the concrete of the reinforced concrete column and is embedded in the foundation. And the upper end part of the said ready-made concrete pile is inserted in the said foundation, It is characterized by the above-mentioned.

  By comprising in this way, since a junction part is realizable with a general reinforced concrete pillar, the improvement of workability can be aimed at. Moreover, the foundation and the ready-made concrete pile can be reliably joined by the anchor reinforcement of the reinforced concrete column which is a joining part.

  According to a third aspect of the present invention, the joint portion is formed of a concrete-filled steel pipe column, the joint portion is disposed in concrete that closes the hollow portion, and an upper end portion of the concrete-filled steel pipe column is in the foundation. In addition to being embedded, the upper end surface of the ready-made concrete pile and the lower end surface of the foundation are arranged to contact each other.

  By comprising in this way, since a junction part is realizable with a general concrete filling steel pipe pillar (CFT steel pipe), improvement of workability can be aimed at. Moreover, a foundation and a ready-made concrete pile can be reliably joined via the CFT steel pipe which is a junction part.

  According to a fourth aspect of the present invention, the joint portion is formed of a concrete-filled steel pipe column, the joint portion is disposed in concrete that closes the hollow portion, and an upper end portion of the concrete-filled steel pipe column is in the foundation. While being embedded, the upper end part of the said ready-made concrete pile is inserted in the said foundation, It is characterized by the above-mentioned.

  By comprising in this way, since a junction part is realizable with a general concrete filling steel pipe pillar (CFT steel pipe), improvement of workability can be aimed at. Moreover, a foundation and a ready-made concrete pile can be reliably joined via the CFT steel pipe which is a junction part.

  The invention described in claim 5 is characterized in that an end plate is provided on an upper end surface of the steel pipe concrete pile, and a rib is attached between the end plate and the inner peripheral surface of the hollow portion.

  With this configuration, when a pulling force acts on the structure, the rib can resist the pulling force.

  In the invention described in claim 6, an end plate is provided on an upper end surface of the steel pipe concrete pile, and a fixing bar is provided on the side of the steel pipe concrete pile in the end plate so as to follow the axial direction of the steel pipe concrete pile. It is characterized by being attached.

  With this configuration, when a pulling force is applied to the structure, the pulling force can be resisted by the fixing muscle.

  The invention described in claim 7 is characterized in that a buffer material is provided on a connection surface between the foundation and the joint.

  By comprising in this way, when axial force acts on a structure, axial force can be transmitted only to a ready-made concrete pile. Therefore, the strength of the joint can be reduced.

  According to the present invention, the axial force is directly transmitted from the foundation to the ready-made concrete pile because the arrangement is made without providing a gap between the ready-made concrete pile and the foundation. In addition, since no anchoring bars are provided between the ready-made concrete pile and the foundation, the bending moment is transmitted from the foundation to the ready-made concrete pile through the joint. Therefore, since it is sufficient that the joint portion has only a necessary bending strength, there is an effect that the strength of the joint portion can be reduced. As a result, since the weight of the joint portion can be reduced, it is possible to improve the workability and reduce the construction cost.

(First embodiment)
Next, a first embodiment of the present invention will be described with reference to FIGS. In each drawing used for the following description, the scale of each member is appropriately changed to make each member a recognizable size. Further, since the figure becomes complicated, the basic reinforcement is not shown.
In the following embodiments, the target pile is a ready-made concrete pile such as an SC pile (centrifugal concrete pile with outer shell steel pipe).

  As shown in FIGS. 1 and 2, the ready-made concrete pile 11 includes a steel pipe 12 having a circular shape in plan view, a concrete part 13 provided on the inner peripheral side of the steel pipe 12, and an inner side of the concrete part 13. It has the formed hollow part 14 and the end plate 15 of the ring view ring shape arrange | positioned so that the upper end surface (on the pile head part 11a) of the concrete part 13 may be covered. In addition, the fixing bars 18 are welded and joined to the end plate 15 on the ready-made concrete pile 11 side in the vertical direction (the material axis direction of the pile). In addition, the steel pipe 12 may have a planar view square shape. Further, the steel pipe 12 and the end plate 15 are joined by welding.

  A reinforced concrete column 21 is provided in the hollow portion 14 of the ready-made concrete pile 11. The reinforced concrete column 21 is arranged in the concrete 22 filled in the hollow portion 14 near the pile head 11a, the hoop 23 arranged in the horizontal direction in the concrete 22, and in the vertical direction (the axial direction of the pile). And anchored anchor muscle 24. The concrete 22 is provided so as to be substantially flush with the upper end surface of the concrete portion 13. The anchor bars 24 are arranged so as to protrude from the concrete 22, and are configured to be embedded in the foundation 31.

  The anchor muscle 24 resists the pulling force generated by the axial force fluctuation at the time of the earthquake. In addition, the amount of anchor bars 24 that do not hinder the adhesion with the concrete 22 is provided.

  A predetermined amount of the upper end portion of the ready-made concrete pile 11 is inserted into the foundation 31. Further, the contact surface between the outer peripheral surface 16 of the steel pipe 12 of the ready-made concrete pile 11 and the foundation 31 is a protective member made of soft urethane or foamed styrene in order to facilitate the pile head rotation and prevent the foundation 31 from being damaged. 33 is interposed.

  According to this embodiment, in the joint structure of the pile head in which the reinforced concrete column 21 as a joint portion is interposed between the pile head 11 a of the ready-made concrete pile 11 and the foundation 31 supported by the ready-made concrete pile 11. The ready-made concrete pile 11 is composed of a steel pipe concrete pile having a hollow portion 14, a reinforced concrete column 21 is disposed in the hollow portion 14 of the ready-made concrete pile 11, and the upper end portion of the ready-made concrete pile 11 is inserted into the foundation 31. Arranged.

  Since it comprised in this way, it arrange | positions and comprises without providing a clearance gap between the ready-made concrete pile 11 and the foundation 31, and axial force is directly transmitted to the ready-made concrete pile 11 from the foundation 31. FIG. In addition, since no fixing bar or the like is provided between the ready-made concrete pile 11 and the foundation 31, the bending moment is transmitted from the foundation 31 to the ready-made concrete pile 11 through the reinforced concrete column 21 that is a joint portion. Therefore, since the reinforced concrete column 21 which is a joining part should just have only a required bending strength, the intensity | strength of the reinforced concrete column 21 can be reduced. As a result, since the weight of the reinforced concrete column 21 can be reduced, the workability can be improved and the construction cost can be reduced.

  Further, by joining the ready-made concrete pile 11 and the foundation 31 via the reinforced concrete column 21 which is a joint portion, the rigidity of the pile head joint portion is lowered and becomes a semi-rigid joint state, and the bending moment acting on the pile head portion 11a. Is reduced. As a result, the pile head 11a is not damaged even by a large earthquake. Furthermore, along with the reduction of the stress of the pile head 11a, the pile body cross section and the foundation frame cross section are reduced, the amount of excavated sand is reduced, and the construction cost and the construction period can be shortened.

Further, the joint portion is constituted by a reinforced concrete column 21 that closes the hollow portion 14, and the anchor bars 24 of the reinforced concrete column 21 are extended from the reinforced concrete column 21 and embedded in the foundation 31.
Since it comprised in this way, a junction part can be implement | achieved with the general reinforced concrete pillar 21, and improvement of workability | operativity can be aimed at. Moreover, the foundation 31 and the ready-made concrete pile 11 can be reliably joined with the anchor reinforcement 24 of the reinforced concrete column 21 which is a junction.

Furthermore, the end plate 15 is provided in the upper end surface (on the pile head 11a) of the ready-made concrete pile 11, and the ready-made concrete pile 11 side in the end plate 15 is along the axial direction of the ready-made concrete pile 11 (vertical direction). An anchoring muscle 18 was attached to.
With this configuration, when a pulling force is applied to the structure, the fixing muscle 18 can resist the pulling force.

(Second embodiment)
Next, a second embodiment of the present invention will be described with reference to FIGS. In addition, in this embodiment, since only the structure of a junction part differs from 1st embodiment and it is substantially equivalent about another structure, the same code | symbol is attached | subjected to the same location and detailed description is abbreviate | omitted.
As shown in FIGS. 3 and 4, the ready-made concrete pile 11 includes a steel pipe 12, a concrete portion 13, a hollow portion 14, and an end plate 15. A fixing bar 18 is welded to the end plate 15 on the ready-made concrete pile 11 side.

  Concrete 41 is filled in the vicinity of the pile head 11 a in the hollow portion 14 of the ready-made concrete pile 11. The concrete 41 is provided so as to be substantially flush with the upper end surface of the concrete portion 13. The concrete 41 is provided with a CFT steel pipe 43 so that one end thereof is buried. The other end of the CFT steel pipe 43 is disposed so as to protrude from the concrete 41 and is configured to be embedded in the foundation 31. In addition, in order to improve the adhesiveness with the concrete 41 and the foundation 31, the slip prevention reinforcing bar 44 is suitably attached to the outer peripheral surface of the CFT steel pipe 43 by welding joining so that the circumferential direction may be followed. The CFT steel pipe 43 resists the pulling force generated by the axial force fluctuation at the time of the earthquake.

  A predetermined amount of the upper end portion of the ready-made concrete pile 11 is inserted into the foundation 31. Further, the contact surface between the outer peripheral surface 16 of the steel pipe 12 of the ready-made concrete pile 11 and the foundation 31 is a protective member made of soft urethane or foamed styrene in order to facilitate the pile head rotation and prevent the foundation 31 from being damaged. 33 is interposed.

According to the present embodiment, the joint between the ready-made concrete pile 11 and the foundation 31 is configured by the CFT steel pipe 43 instead of the reinforced concrete column in the first embodiment. Further, the CFT steel pipe 43 is disposed on the concrete 41 that closes the hollow portion 14, and the foundation 31 and the ready-made concrete pile 11 are connected via the CFT steel pipe 43.
Even if comprised in this way, the effect substantially equivalent to 1st embodiment can be exhibited.

(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIGS. In this embodiment, the second embodiment differs from the second embodiment only in the method of joining the ready-made concrete pile and the foundation, and the other components are substantially equivalent, so the same portions are denoted by the same reference numerals for detailed description. Omitted.
As shown in FIGS. 5 and 6, the ready-made concrete pile 11 includes a steel pipe 12, a concrete portion 13, a hollow portion 14, and an end plate 15. Further, the end plate 15 is projected over the hollow portion 14 by a predetermined distance to form an overhanging portion 15a. A rib 19 is attached between the projecting portion 15 a of the end plate 15 and the inner peripheral surface 14 a of the hollow portion 14. The overhanging portion 15a and the rib 19 are joined by welding.

  Concrete 41 is filled in the vicinity of the pile head 11 a in the hollow portion 14 of the ready-made concrete pile 11. The concrete 41 is provided so as to be substantially flush with the upper end surface of the concrete portion 13. The concrete 41 is provided with a CFT steel pipe 43 so that one end thereof is buried. The other end of the CFT steel pipe 43 is disposed so as to protrude from the concrete 41 and is configured to be embedded in the foundation 31. A slip prevention reinforcing bar 44 is attached to the outer peripheral surface of the CFT steel pipe 43.

  Moreover, the upper end surface 11b of the ready-made concrete pile 11 and the lower end surface 31a of the foundation 31 are arrange | positioned so that it may contact | abut.

According to this embodiment, the joint part of the ready-made concrete pile 11 and the foundation 31 is comprised with the CFT steel pipe 43 similarly to 2nd embodiment. Further, the CFT steel pipe 43 is disposed on the concrete 41 that closes the hollow portion 14, and the foundation 31 and the ready-made concrete pile 11 are connected via the CFT steel pipe 43. Moreover, it arrange | positioned so that the ready-made concrete pillar 11 and the foundation 31 may contact | abut. Further, a rib 19 is provided in place of the fixing muscle 18 used in the first embodiment and the second embodiment.
Even if comprised in this way, the effect substantially the same as 1st embodiment and 2nd embodiment can be exhibited.

(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described with reference to FIG. In the present embodiment, the only difference is that a cushioning material is added to the first embodiment, and the other components are substantially the same. Therefore, the same portions are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 7, a reinforced concrete column 21 is provided in the hollow portion 14 of the ready-made concrete pile 11. The reinforced concrete column 21 has concrete 22, hoop bars 23, and anchor bars 24. The concrete 22 is provided so as to be substantially flush with the upper end surface of the concrete portion 13. The anchor bars 24 are arranged so as to protrude from the concrete 22, and are configured to be embedded in the foundation 31. Here, the buffer material 51 is provided so as to cover the upper surface 22 a of the concrete 22. The buffer material 51 is made of a cushion material such as a styrofoam.

According to the present embodiment, the buffer material 51 is provided on the upper surface 22a of the concrete 22 that is a connection surface between the foundation 31 and the reinforced concrete column 21 that is a joint.
Since it comprised in this way, in addition to the effect of 1st embodiment, when axial force acts on a structure, axial force can be reliably transmitted only to the ready-made concrete pile 11. FIG. Accordingly, it is possible to reduce the strength of the reinforced concrete column 21 that is a joint.

(Fifth embodiment)
Next, a fifth embodiment of the present invention will be described with reference to FIG. In the present embodiment, the only difference is that a cushioning material is added to the second embodiment, and other configurations are substantially the same. Therefore, the same portions are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 8, concrete 41 is filled in the vicinity of the pile head 11 a in the hollow portion 14 of the ready-made concrete pile 11. The concrete 41 is provided so as to be substantially flush with the upper end surface of the concrete portion 13. The concrete 41 is provided with a CFT steel pipe 43 so that one end thereof is buried. The other end of the CFT steel pipe 43 is disposed so as to protrude from the concrete 41 and is configured to be embedded in the foundation 31. A slip prevention reinforcing bar 44 is attached to the outer peripheral surface of the CFT steel pipe 43. Here, the cushioning material 52 is provided so as to cover the upper surface 43a of the other end of the CFT steel pipe 43 and the upper surface 44a of the slip prevention reinforcing bar 44 located in the foundation 31. The cushioning material 52 is made of a cushion material such as a styrofoam.

According to the present embodiment, the buffer material 52 is provided on the upper surface 43a of the CFT steel pipe 43 and the upper surface 44a of the misalignment prevention reinforcing bar 44, which are connection surfaces between the foundation 31 and the CFT steel pipe 43 that is the joint.
Since it comprised in this way, in addition to the effect of 2nd embodiment, when axial force acts on a structure, axial force can be reliably transmitted only to the ready-made concrete pile 11. FIG. Accordingly, it is possible to reduce the strength of the CFT steel pipe 43 that is a joint.

(Sixth embodiment)
Next, a sixth embodiment of the present invention will be described with reference to FIG. In the present embodiment, the only difference is that a cushioning material is added to the third embodiment, and other configurations are substantially the same. Therefore, the same portions are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 9, concrete 41 is filled in the vicinity of the pile head 11 a in the hollow portion 14 of the ready-made concrete pile 11. The concrete 41 is provided so as to be substantially flush with the upper end surface of the concrete portion 13. The concrete 41 is provided with a CFT steel pipe 43 so that one end thereof is buried. The other end of the CFT steel pipe 43 is disposed so as to protrude from the concrete 41 and is configured to be embedded in the foundation 31. A slip prevention reinforcing bar 44 is attached to the outer peripheral surface of the CFT steel pipe 43. Here, the cushioning material 52 is provided so as to cover the upper surface 43a of the other end of the CFT steel pipe 43 and the upper surface 44a of the shift prevention reinforcing bar 44 located in the foundation 31. The cushioning material 52 is made of a cushion material such as a styrofoam.

According to the present embodiment, the buffer material 52 is provided on the upper surface 43a of the CFT steel pipe 43 and the upper surface 44a of the misalignment prevention reinforcing bar 44, which are connection surfaces between the foundation 31 and the CFT steel pipe 43 that is the joint.
Since it comprised in this way, in addition to the effect of 3rd embodiment, when axial force acts on a structure, axial force can be reliably transmitted only to the ready-made concrete pile 11. FIG. Accordingly, it is possible to reduce the strength of the CFT steel pipe 43 that is a joint.

  It should be noted that the technical scope of the present invention is not limited to the above-described embodiment, and includes those in which various modifications are made to the above-described embodiment without departing from the spirit of the present invention. That is, the specific materials, configurations, and the like given in the embodiment are merely examples, and can be changed as appropriate.

For example, in the present embodiment, when the joint portion is a reinforced concrete column, the case where the fixing bar is disposed on the ready-made concrete pile has been described, but a rib may be provided.
Moreover, in this embodiment, although the joint part was made into the CFT steel pipe and the ready-made concrete pile was inserted in the foundation, the case where a fixing reinforcement was arrange | positioned to the ready-made concrete pile was demonstrated, You may provide a rib.
Furthermore, in this embodiment, when the joint portion is a CFT steel pipe and the ready-made concrete pile is arranged so as to come into contact with the foundation, a description has been given of a case where a rib is arranged on the ready-made concrete pile, but a fixing bar is provided. Also good.

It is an elevation sectional view showing the joining structure of the pile head in the first embodiment of the present invention. It is sectional drawing which follows the AA line of FIG. It is an elevation sectional view showing the joining structure of the pile head in the second embodiment of the present invention. It is sectional drawing which follows the BB line of FIG. It is an elevation sectional view showing the joining structure of the pile head in the third embodiment of the present invention. It is sectional drawing which follows the CC line of FIG. It is a sectional elevation showing the joining structure of the pile head in a fourth embodiment of the present invention. It is a sectional elevation showing the joining structure of the pile head in a fifth embodiment of the present invention. It is a sectional elevation showing the joining structure of the pile head in a sixth embodiment of the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Ready-made concrete pile 11a ... Pile head 11b ... Upper end surface 14 ... Hollow part 14a ... Inner peripheral surface 15 ... End plate 18 ... Fixing bar 19 ... Rib 21 ... Reinforced concrete pillar (joint part) 24 ... Anchor bar 31 ... Foundation 31a ... Lower end face 43 ... CFT steel pipe (joint, concrete-filled steel pipe column) 51, 52 ... Buffer material

Claims (7)

In the joint structure of the pile head where the joint is interposed between the pile head of the ready-made concrete pile and the foundation supported by the ready-made concrete pile,
The ready-made concrete pile is composed of a hollow steel pipe concrete pile,
In the hollow portion of the steel pipe concrete pile, the joint is arranged so that one end protrudes toward the foundation side,
The pile head joint structure, wherein the ready-made concrete pile and the foundation are arranged so as to be connected to each other. The joint portion is composed of a reinforced concrete column that closes the hollow portion,
The anchor bars of the reinforced concrete columns extend from the concrete of the reinforced concrete columns and are embedded in the foundation,
The joint structure of the pile head according to claim 1, wherein an upper end portion of the ready-made concrete pile is inserted into the foundation. The joint is composed of a concrete-filled steel pipe column,
The joint is disposed in the concrete that closes the hollow portion,
While the upper end of the concrete-filled steel pipe column is embedded in the foundation,
2. The pile head joint structure according to claim 1, wherein the upper end surface of the ready-made concrete pile and the lower end surface of the foundation are arranged to contact each other. The joint is composed of a concrete-filled steel pipe column,
The joint is disposed in the concrete that closes the hollow portion,
While the upper end of the concrete-filled steel pipe column is embedded in the foundation,
The joint structure of the pile head according to claim 1, wherein an upper end portion of the ready-made concrete pile is inserted into the foundation. An end plate is provided on the upper end surface of the steel pipe concrete pile,
5. The pile head joint structure according to claim 1, wherein a rib is attached between the end plate and the inner peripheral surface of the hollow portion. An end plate is provided on the upper end surface of the steel pipe concrete pile,
The pile head according to any one of claims 1 to 4, wherein a fixing bar is attached to the steel plate concrete pile side of the end plate so as to follow the axial direction of the steel pipe concrete pile. Bonding structure.   The pile head joint structure according to any one of claims 1 to 6, wherein a cushioning material is provided on a connection surface between the foundation and the joint portion.

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