JP5251760B2 - Pile head connection structure and its construction method - Google Patents

Description

The present invention relates to a pile head coupling structure for coupling a pile having a steel pipe part at least to a pile head and a reinforced concrete structure.
In addition, the reinforced concrete structure couple | bonded with a pile means that what is directly couple | bonded with a pile is a reinforced concrete structure, and does not mean that the structure of the upper part is also a reinforced concrete.

With the development of high-bearing-type steel pipe piles such as rotating piles and steel-pile soil-cement piles, the load acting on each pile (always during an earthquake) has increased. Along with this, a large load is also generated at the joint between the pile and the superstructure.
As a conventional pile head connection structure, for example, a pile shown as method B in the road bridge specification form in which a slip stopper is installed on the inner surface of the pile head of a steel pipe pile and an intermediate reinforcing reinforcement is arranged on the inner periphery of the pile head There is a head coupling method. However, with this method, it is difficult to obtain a sufficient strength of the pile head joint with respect to the strength of the pile body, and there is a concern that the entire foundation structure becomes unstable due to insufficient strength of the joint.

  In addition, as a pile head connection structure that strengthens Method B described in the Road Bridge Specification, there is a method of on-site welding of reinforcing bars to the outer periphery of the pile. May fall. In addition, this method involves welding rebars to steel pipe piles at the construction site, so the strength and durability of welds may be impaired due to work in bad weather such as rain or strong winds and differences in welding technology levels. .

  As an example of a pile head coupling structure having a stable high bending strength, there is a “joint structure of steel pipe pile heads and a construction method of steel pipe pile heads” disclosed in Prior Literature 1. In this steel pipe pile head joint structure, an outer steel pipe to which anchoring bars are fixed is disposed around the head of the steel pipe pile placed in the ground, and the gap between the outer steel pipe and the steel pipe pile and the A steel pipe pile head joint structure in which concrete is cast around at least the upper end of the outer steel pipe, and the steel pipe pile and the footing or the foundation beam are joined to each other. A protruding fixing member is provided (see claim 1 of Patent Document 1).

JP 2005-139731 A

The thing described in the above-mentioned prior art document 1 has a structure in which a fixing bar is fixed around the outer steel pipe, and a fixing member protruding to the pile side is installed at the lower end portion of the outer steel pipe.
In the case of such a structure, the upper end of the outer steel pipe protrudes above the upper end of the pile due to the risk of interference with the reinforcement of the upper reinforced concrete structure and insufficient load transmission. I can't.
Moreover, since the load transmission will become inadequate when the upper end of an outer steel pipe is located below the pile upper end, it is unpreferable.
Thus, in the thing of the prior art document 1, it is necessary to make the upper end position of an outer steel pipe correspond with a pile upper end position, Therefore, it is essential that an outer steel pipe has the predetermined | prescribed length extended below from a pile upper end.
Thus, since it becomes indispensable that an outer steel pipe has predetermined length, in the joining structure of the steel pipe pile head of prior art literature 1, there are the following problems.

When construction errors such as high and low piles and pile misalignment occur, it is difficult to deal with them. This point will be specifically described below.
(a) Even if the pile stays high, the upper end of the outer steel pipe must be aligned with the upper end of the pile. There is a possibility that a problem may occur in the contact with. In that case, it is conceivable to adjust the length of the anchoring reinforcing bar, but if so, load transmission may be insufficient.
(b) On the other hand, if the pile is stuck low, the upper end of the outer steel pipe cannot be extended above the upper end of the pile and must be aligned with the upper end of the pile. There is a risk that the length of the fixing muscles is insufficient and the load transmission is insufficient.
(c) Moreover, when pile center shift | offset | difference arises, since it will absorb shift | offset | difference between an outer steel pipe and a steel pipe pile, in the structure of patent document 1, since the fixing member has protruded to the pile side, The gap between the outer steel pipe and the steel pipe pile cannot be accommodated because there is not enough room to absorb the displacement. Moreover, when the pile is inclined as another aspect of the pile misalignment, there is a risk that the gap between the outer steel pipe and the pile becomes uneven in the vertical direction and load transmission becomes uncertain.
Thus, in the thing of patent document 1, there exists a problem that it receives to the influence of the construction error of a pile.

Moreover, in the thing of the prior document 1, a fixing reinforcement must be welded to the surrounding surface of an outer steel pipe, and a fixing member must be fixed to the lower end part of an outer steel pipe, and there are many members to assemble in advance, and production is troublesome. There is a problem that it takes.
Furthermore, since the outer steel pipe requires a predetermined length, there is a problem that the overall shape becomes large, and transportation to the site and handling at the site are not easy.

The present invention has been made to solve such problems, and provides a pile head coupling structure and a construction method thereof that are easy to construct and have high strength corresponding to an increase in pile head reaction force accompanying an increase in pile strength. The purpose is to do.
In addition, the purpose of the present invention is to provide a pile head coupling structure that is easy to manufacture and excellent in handling, and its construction method, without being affected by construction errors due to pile construction errors such as pile high and low piles, It is said.

(1) A pile head coupling structure according to the present invention is a pile head coupling structure for coupling a reinforced concrete structure with a pile having a steel pipe portion at least at the pile head, and the detent provided on the steel pipe portion; A ring member that is inserted through the steel pipe portion and disposed below the stopper, and a U-shaped portion that is U-shaped by bending a lower end thereof, and the U-shaped portion An upper end that rises from the U-shaped portion and holds the ring member so as to sandwich the fixing member extends upward from the pile head, and is placed on the pile head including the fixing reinforcing bar and the ring member. It is characterized by being provided with concrete.

(2) A pile head coupling structure that couples a pile having a steel pipe part at least to the pile head and a reinforced concrete structure, the slip stopper provided in the steel pipe part, inserted through the steel pipe part, and the slip stopper A connecting portion formed by connecting a ring member disposed below and a lower end portion of a plurality of reinforcing bars arranged in parallel at a predetermined interval via a support plate, and the ring member is An upper end portion that is held and has an upper end portion that rises from the connection portion extends upward from the pile head, and includes a concrete that is placed on the pile head including the fixing rebar and the ring member. Characteristic pile head connection structure.

(3) Further, in the above (1) or (2), the distance H (mm) from the upper end surface of the ring member to the lower end position of the slip stopper installed at the lowest level satisfies the following formula. The ring member is arranged as described above.
H ≧ Din-φ
However, Din: Inner diameter of ring member (mm)
φ: Pile diameter of steel pipe pile (mm)

(4) Further, in any of the above (1) to (3), the width W (mm) of the ring member satisfies the following expression.
W ≧ t × s
However, t: Height of slip prevention (mm)
s: Number of steps of slip prevention

(5) Moreover, the thing in any one of said (1) thru | or (4) WHEREIN: The center of the said ring member and the pile core of the said steel pipe pile correspond, It is characterized by the above-mentioned.

(6) The pile head coupling structure construction method according to the present invention is the pile head coupling structure construction method according to any one of the above (1) to (5), and a pile driving step of driving a pile. A ring member holding step for holding the ring member by a plurality of fixing rebars, and a ring member so that the ring members held by the plurality of fixing rebars are inserted through the steel pipe portion and below the detents It has a ring member installation process which installs, and a concrete placement process which casts concrete into a pile head.

  In the present invention, the stopper provided in the steel pipe part, the ring member that is inserted through the steel pipe part and disposed below the stopper, and the lower end part is bent to form a U shape. A fixing reinforcing bar having a U-shaped part, holding the ring member between the U-shaped part and having an upper end rising from the U-shaped part extending above the pile head, and the fixing By providing a reinforcing bar and concrete placed on the pile head including the ring member, the ring member functions as a bearing part, and corresponds to an increase in the pile head reaction force accompanying the increase in pile strength. A pile head connection structure that is high in strength and easy to manufacture without being affected by construction errors due to pile construction errors.

It is explanatory drawing of the pile head coupling | bonding structure which concerns on one embodiment of this invention. It is sectional drawing which follows the arrow AA line in FIG. 1, Comprising: It is the figure which abbreviate | omitted and showed the concrete around a steel pipe pile. It is explanatory drawing of the pile head coupling | bonding structure which concerns on one embodiment of this invention, Comprising: It is a figure explaining the arrangement | positioning relationship of each member. It is explanatory drawing of the pile head coupling | bonding structure which concerns on one embodiment of this invention, Comprising: It is a figure explaining the arrangement | positioning relationship of each member. It is explanatory drawing of the pile head coupling | bonding structure which concerns on Embodiment 2 of this invention. It is sectional drawing which follows the arrow BB line in FIG. 5, Comprising: It is the figure which abbreviate | omitted and showed the concrete around a steel pipe pile. It is explanatory drawing of the pile head coupling | bonding structure which concerns on the other aspect of Embodiment 2 of this invention. It is explanatory drawing of the pile head coupling | bonding structure which concerns on Embodiment 3 of this invention. It is sectional drawing which follows the arrow CC line in FIG. 8, Comprising: It is the figure which abbreviate | omitted the concrete around a steel pipe pile. It is explanatory drawing of the pile head coupling | bonding structure which concerns on Embodiment 4 of this invention. It is explanatory drawing of the pile head coupling | bonding structure which concerns on Embodiment 5 of this invention. It is explanatory drawing of the construction method of the pile head coupling | bonding structure which concerns on Embodiment 6 of this invention. It is explanatory drawing of the construction method of the pile head coupling | bonding structure which concerns on Embodiment 6 of this invention.

[Embodiment 1]
A first embodiment of the present invention will be described with reference to FIGS.
The pile head coupling structure according to the first embodiment of the present invention is a pile head coupling structure for coupling a steel pipe pile 1 and a foundation beam 3 which is a reinforced concrete structure, as shown in FIGS. Two-stage stoppers 5a and 5b provided on the pile head of the pile 1, a ring member 7 inserted through the pile head of the steel pipe pile 1 and disposed below the lower stopper 5b, and a lower end portion Has a U-shaped portion 8 that is U-shaped by being bent by 180 °, and holds the ring member between the U-shaped portion 8 and the upper end portion rising from the U-shaped portion 8 is a pile head It is characterized by comprising a fixed reinforcing bar 9 extending upward from the section, and a concrete 11 placed on a pile head including the fixing reinforcing bar 9 and the ring member 7.
Hereinafter, each configuration will be described in detail.

<Steel pipe pile>
The pile head inside the steel pipe pile 1 may be filled with concrete 12 as shown in FIG. 2, or may not be filled with concrete.
In this embodiment, the steel pipe pile 1 is taken as an example. However, the pile targeted by the present invention is not limited to the steel pipe pile 1, and the lower structure other than the pile head is provided if at least the pile head has a steel pipe. May be a pile that is not a steel pipe or a pile that is filled with concrete over the entire length inside the pile. For example, earthquake-resistant cast-in-place concrete piles (known as TB piles) with steel pipes wound around the pile heads, and steel pipe concrete piles (SC piles) manufactured by injecting high-strength concrete into the hollow portions of steel pipes and centrifugal compaction It is done.

<Foundation beam>
The foundation beam 3 corresponds to the reinforced concrete structure of the present invention. The foundation beam 3 is provided with a bottom bar 14.
In addition, the reinforced concrete structure of this invention has pointed out the part directly couple | bonded with the steel pipe pile 1. FIG. Therefore, if the portion directly coupled to the steel pipe pile 1 is a reinforced concrete structure, the upper structure may be a structure that is not a reinforced concrete structure such as a steel structure.

<Slip prevention>
The slip stoppers 5 a and 5 b are members that are provided on the pile heads and transmit force to and from the ring member 7 through the concrete 11. In this embodiment, the stoppers 5a and 5b are provided in two stages as shown in FIG. 1. However, the present invention is not limited to this, and may be one stage or three or more stages. The uppermost stopper 5a may be an end plate protruding outside the pile diameter, or may be a ring member 7 fixed to the pile peripheral surface. The second-stage detent 5b in the present embodiment is obtained by fixing the ring member 7 to the circumferential surface of the pile.

  The form of the stoppers 5a and 5b is not limited to the end plate and the ring member 7 as described above, and may be, for example, irregularities formed on the pile head peripheral surface.

<Ring member>
The ring member 7 is a member that is inserted into the pile head of the steel pipe pile 1 and is disposed below the detents 5b and transmits force between the detents 5a and 5b via the concrete 11.
The upper surface of the ring member 7 functions as a pressure bearing portion, and transmits stress between the stoppers 5a and 5b.

When the distance from the upper end surface of the ring member 7 to the lower end position of the second stage stopper 5b is H (see FIG. 3), the ring member 7 is preferably arranged so that H (mm) satisfies the following formula. .
H ≧ Din-φ
However, Din: Inner diameter of ring member (mm)
φ: Pile diameter of steel pipe pile (mm)

  By setting the value of H as described above, the stress transmission between the stoppers 5a and 5b and the ring member 7 can be made sufficient.

Further, when the width of the ring member 7 is W (see FIG. 4), it is preferable that W (mm) satisfies the following formula.
W ≧ t × s
However, t: Height of slip prevention (mm)
s: Number of steps of slip prevention

  By making W satisfy the above equation, the stress transmission between the detents 5a and 5b and the ring member 7 can be made sufficient.

It is desirable for the horizontal position of the ring member 7 to coincide with the center of the pile core and the ring member 7 so as not to create a weak spot due to stress transmission between the stoppers 5a and 5b and the ring member 7.
Although it is possible to increase the diameter of the ring member 7, it is necessary to increase the installation depth of the ring member 7, and the length of the fixed reinforcing bars and the amount of concrete placement increase, which is uneconomical. It is possible. Therefore, it is desirable that the inner diameter Din of the ring member 7 be within about twice the pile diameter φ.

  The height of the ring member 7 is not particularly limited, and when the tensile force is applied from the fixing rebar 9, the portion that comes into contact with the fixing rebar 9 is not broken and has a strength that can resist the bearing pressure at that time. As long as it has, the length like the outer steel pipe of patent document 1 is not required. The height that can normally be assumed in the ring member 7 is about 100 mm to 150 mm. However, when higher strength is required, the height may be about 200 mm to 300 mm.

<Fixing rebar>
The fixing reinforcing bar 9 has a U-shaped portion 8 which is U-shaped by bending its lower end portion by 180 °, and the U-shaped portion 8 holds the ring member 7 therebetween. And the upper end part which stands | starts up from the U-shaped part 8 is extended upwards from the pile head. A plurality of fixing rebars 9 (12 in this example) are arranged at predetermined intervals in the circumferential direction of the ring member 7.

In the present embodiment configured as described above, the ring member 7 is a reinforcing bar holding member and functions as a supporting member that transmits stress between the stoppers 5a and 5b, and has a high strength pile head connection. The structure can be realized.
Moreover, since the height of the ring member 7 of this Embodiment is remarkably smaller than the outer steel pipe of patent document 1, it is a more free position with respect to the construction errors of a pile, such as a high stop of a pile and a low stop. The ring member 7 can be arranged to cope with this, and is not affected by the construction error of the pile.

  Further, in the present embodiment, since the fixing reinforcing bar 9 is held by the ring member 7 having a diameter larger than the pile diameter, the reinforcing bar diameter of the fixing reinforcing bar 9 can be increased. This improves the cross-sectional performance (proportional to the square of the diameter) of the pile head joint, which increases the resistance (strength) to the bending moment acting on the pile head, and the pile head associated with the increased strength of steel pipe piles A “pile head connection structure” corresponding to an increase in reaction force can be obtained.

Furthermore, since the distance between the adjacent reinforcing bars 9 can be increased by increasing the bar arrangement diameter, the construction is facilitated, and the reinforcing bar positions are set so that the fixing reinforcing bars 9 are not buffered by the foundation beam (footing) that tends to be an overcrowded arrangement. It is also possible to adjust.
In this regard, even if the outer steel pipe shown in Patent Document 1 is used, it is possible to increase the diameter of the outer steel pipe. However, since the outer steel pipe requires a predetermined length, if the outer steel pipe is increased in diameter, the outer steel pipe has a larger diameter. Although the steel pipe becomes large and transportation and handling become difficult, this embodiment does not have such a problem because the ring member 7 that does not require a large length in the vertical direction is used.

  Moreover, in the conventional method, the fixed reinforcement of the pile head is mostly a single reinforcement, but in this embodiment, since the reinforcement is bent, multiple reinforcements (double) are provided. The structural performance equivalent to the conventional one can be obtained with a rebar having a diameter. At the same time, there is a merit that the length of reinforcing bar fixing to the concrete 11 can be shortened by forming multiple reinforcing bars in which the reinforcing bars are reduced in diameter.

Further, in this embodiment, since it is a simple structure having the ring member 7 and the fixing reinforcing bar 9 as main components, the construction can be simplified and the “pile head coupling structure” is excellent in economy. .
Furthermore, in the present embodiment, since the ring member 7 is held by the U-shaped portion 8 of the fixing reinforcing bar 9, work such as on-site welding and bolt joining is unnecessary, and the construction can be simplified. Since there is no welding failure that occurs in field welding, it is also a “pile head connection structure” with high quality reliability.

As an example of the present embodiment, a pile head coupling structure was implemented with the following specifications.
Outer bar diameter D1 (see Fig. 1) = 1640mm
Inner reinforcement diameter D2 (see Fig. 1) = 1500mm
Steel pipe pile diameter φ = 1000mm
Ring member outer diameter: 1600mm, inner diameter: 1520mm, sectional shape: 120mm (height) x 40mm (width)
Anchoring bar: Folding bar D22-14

  Compared with the structure realized by the method B described in the above-mentioned road bridge specifications, the pile head joint structure having the same strength as the above embodiment can reduce the amount of reinforcing bars to about 45%, and the adjacent reinforcing bars The interval could be expanded up to 4 times. From this, it can be seen that the pile head coupling structure of this example is an excellent structure in terms of cost and construction.

[Embodiment 2]
5 and 6 are explanatory views of a pile head coupling structure according to Embodiment 2 of the present invention, and the same or corresponding parts as those in FIGS. 1 and 2 are denoted by the same reference numerals. 6 is a cross-sectional view taken along the line BB in FIG. 5, and is a view in which the concrete 11 around the steel pipe pile 1 is omitted.
In the present embodiment, the connecting portion is formed by connecting the lower ends of two fixed reinforcing bars 9 arranged in parallel at a predetermined interval in the pile radial direction by a donut-like plate 15 that functions as a supporting plate. 16 is formed. A screw portion 17 is formed at the lower end portion of the fixing reinforcing bar 9, and the screw portion 17 is passed through a through hole formed in the donut-like plate 15 and fixed by a fixing nut 19.
Since the doughnut-shaped plate 15 is continuous in the circumferential direction, the donut-shaped plate 15 also functions as a concrete formwork, which can simplify the formwork at the time of placing concrete and between the stoppers 5a, 5b and the ring member 7. Stress transmission can be made more satisfactory.

  As shown in FIG. 7, a rectangular support plate 21 may be provided for each pair of fixing reinforcing bars 9 instead of the donut-shaped plate 15.

[Embodiment 3]
8 and 9 are explanatory views of a pile head coupling structure according to Embodiment 3 of the present invention, and the same or corresponding parts as those in FIGS. 1 and 2 are denoted by the same reference numerals. FIG. 9 is a cross-sectional view taken along the line CC of FIG. 8 and shows the concrete 11 around the steel pipe pile 1 omitted.
In the present embodiment, the support plate 23 is installed on the upper surface of the ring member 7 at a plurality of locations.
By installing the bearing plate 23, the load transmission capacity from the foundation beam 3 to the steel pipe pile 1 can be enhanced.
[Embodiment 4]
FIG. 10 is an explanatory diagram of a pile head coupling structure according to Embodiment 4 of the present invention, and the same or corresponding parts as those in FIG.
In the present embodiment, the hoop muscle 25 is installed on the pile head so as to surround the ring member 7. By installing the hoop reinforcement 25, the load transmission capability from the foundation beam 3 to the steel pipe pile 1 can be enhanced.

[Embodiment 5]
FIG. 11 is an explanatory view of a pile head coupling structure according to Embodiment 5 of the present invention, and the same or corresponding parts as those in FIG.
In the present embodiment, a steel pipe 27 is installed on the pile head so as to surround the ring member 7. By installing the steel pipe 27, it can be used as a formwork at the time of placing concrete, and can also be used as a concrete restraining member after placing concrete, and the load transmission ability from the foundation beam 3 to the steel pipe pile 1 can be enhanced.

[Embodiment 6]
12 and 13 are explanatory diagrams of the construction method of the pile head coupling structure shown in FIG. Hereinafter, the present embodiment will be described with reference to FIGS.
The steel pipe pile 1 is driven on the ground 29 (FIG. 12 (a)). Next, the ring member 7 is held by the bent U-shaped portion 8 of the fixing reinforcing bar 9, and the ring member 7 is disposed at a predetermined position of the pile head (FIG. 12B). As described in the first embodiment, the predetermined position is a position where the distance H (mm) from the upper end surface of the ring member 7 to the lower end position of the second-stage detent 5b satisfies the following expression.
H ≧ Din-φ
However, Din: Inner diameter of ring member (mm)
φ: Pile diameter of steel pipe pile (mm)

  In addition, since the freedom degree of the vertical arrangement | positioning with respect to the pile head of the ring member 7 is high at the time of installation of the ring member 7, even if it is a case where a pile stops at a high level or a low level, a pile head Can be installed in an optimal position. Further, even when the pile core is displaced, the ring member 7 can be arranged at the optimum position with respect to the foundation beam 3 because the ring member 7 has a high degree of freedom in the horizontal direction with respect to the steel pipe pile 1.

  After the ring member 7 is installed, the formwork 31 is installed so as to surround the ring member 7 and the fixing reinforcing bar 9, and the concrete 11 is placed (FIG. 13C). After the concrete 11 is solidified, the foundation beam 3 is laid and the concrete of the foundation beam is placed (FIG. 13D).

  According to the present embodiment, it is possible to realize a pile head coupling structure capable of reliably transmitting stress without being affected by pile construction errors.

DESCRIPTION OF SYMBOLS 1 Steel pipe pile 3 Foundation beam 5a, 5b Detachment 7 Ring member 8 U-shaped part 9 Anchor reinforcement 11 Concrete 12 Concrete 14 Bottom reinforcement 15 Donut-shaped board 16 Connection part 17 Screw part 19 Fixing nut 21 Supporting pressure plate 23 Supporting pressure plate 25 Hoop Muscle 27 Steel pipe 29 Ground 31 Formwork

Claims (6)

A pile head coupling structure for coupling a reinforced concrete structure with a pile having a steel pipe at least at the pile head,
A U-shaped portion formed into a U-shape by bending a lower end portion thereof, a stopper provided in the steel pipe portion, a ring member inserted through the steel pipe portion and disposed below the stopper. A fixing rebar that holds the ring member between the U-shaped portion and has an upper end that rises from the U-shaped portion extends above the pile head, and the fixing rebar and the ring. A pile head coupling structure comprising: a concrete casted on the pile head including a member. A pile head coupling structure for coupling a reinforced concrete structure with a pile having a steel pipe at least at the pile head,
A support plate that includes a stopper provided in the steel pipe part, a ring member that is inserted through the steel pipe part and disposed below the stopper, and the lower ends of a plurality of reinforcing bars that are arranged in parallel at a predetermined interval. A fixing portion that is connected via the fixing portion, the fixing member that holds the ring member at the connecting portion and that has an upper end that rises from the connecting portion extends upward from the pile head, A pile head coupling structure comprising: a concrete cast on the pile head including the ring member. The ring member is disposed such that a distance H (mm) from an upper end surface of the ring member to a lower end position of the slip stopper installed at the lowest level satisfies the following formula: 2. Pile head coupling structure according to 2.
H ≧ Din-φ
However, Din: Inner diameter of ring member (mm)
φ: Pile diameter of steel pipe pile (mm) The pile head coupling structure according to any one of claims 1 to 3, wherein a width W (mm) of the ring member satisfies the following formula.
W ≧ t × s
However, t: Height of slip prevention (mm)
s: Number of steps of slip prevention   The pile head coupling structure according to any one of claims 1 to 4, wherein a center of the ring member and a pile core of the steel pipe pile coincide with each other. A construction method for a pile head coupling structure according to any one of claims 1 to 5,
Pile driving process for driving a pile, a ring member holding process for holding the ring member in a U-shaped part of a plurality of fixing reinforcing bars, and the ring member held by a plurality of fixing reinforcing bars being inserted into the steel pipe part The construction of a pile head connection structure comprising: a ring member installation step of installing a ring member so as to be below the slip stopper; and a concrete placement step of placing concrete on the pile head Method.

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