JP2010090596A - Joint structure of pile and foundation skeleton, joining method for pile and foundation skeleton, and pc member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a joint structure of a pile and a foundation skeleton applicable even when a vertical load imposed on a pile is large and reducing a bending load at a joint part. <P>SOLUTION: The joint structure 10 of the concrete pile 30 and the foundation skeleton 20 includes a small diameter part 40 formed between the pile 30 and the foundation skeleton 20, smaller in diameter than the pile 30 and separated from the foundation skeleton 20; a first steel pipe 41 surrounding the small diameter part 40; and a second steel pipe 42 penetrating the small diameter part 40 so that the upper end is embedded in the foundation skeleton 20 and the lower end is embedded in the head of the pile 30. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a joint structure in which bending rigidity at a joint portion between a pile and a foundation frame is reduced.

  Conventionally, when a pile foundation is used in a foundation such as a building, the foundation footing is constructed so that the pile head is embedded so that vertical load and shear force can be transmitted between the foundation footing and the pile. Yes. However, in such a configuration, when a horizontal force acts on the building, a large bending load is generated at the joint between the foundation footing and the pile. For this reason, it is necessary to arrange a large number of reinforcing bars so that sufficient bending strength can be secured at the joint between the foundation footing and the pile, which increases the amount of reinforcing bars and takes time and effort.

On the other hand, for example, in Patent Document 1, by forming a frustum-shaped support section on the top of the pile head, and by placing the structure foundation on the top of the support section, A method for reducing the bending load generated at the joint is described.
Japanese Patent No. 3661997

  However, in the above method, if the diameter of the bearing section is too small, the bearing section may be damaged when a load corresponding to the maximum support force of the pile is applied to the bearing section. For this reason, when the vertical load which a pile bears is large, the diameter of a bearing part cannot be reduced significantly, but there exists a problem that the reduction effect of a sufficient bending load cannot be acquired.

  The present invention has been made in view of the above-described problems, and the purpose of the present invention is to join a pile and a foundation frame that can be applied even when the vertical load borne by the pile is large and can reduce the bending load at the joint. Is to provide a structure.

The joint structure of the pile and the foundation frame of the present invention is a joint structure of a concrete pile and the foundation chassis, formed between the pile and the foundation chassis, and the cross section is smaller than the cross section of the pile, and , A small cross-sectional portion that is edge-separated between at least one of the pile and the foundation frame, a restraining member that constrains the small cross-sectional portion in the circumferential direction, and penetrates through the small cross-sectional portion, and an upper end is A steel pipe embedded in the foundation frame and having a lower end embedded in the head of the pile.
Said joining structure WHEREIN: You may provide the 2nd restraint member which restrains the upper part of the said pile in the circumferential direction.

Further, the method for joining a pile and a foundation frame of the present invention is a method for joining a concrete pile and a foundation frame, and the cross section between the pile and the foundation frame is small compared to the cross section of the pile. A cross-sectional portion is provided such that at least one of the pile and the foundation frame is severably separated, a restraining member is provided to restrain the small cross-sectional portion in the circumferential direction, and the inside of the small cross-sectional portion is provided. A steel pipe is provided so that it penetrates, the upper end is embedded in the foundation frame, and the lower end is embedded in the head of the pile.
Further, the PC member of the present invention includes a concrete pile and a foundation frame, and a small cross section between the pile and the foundation frame having a small cross section compared to the cross section of the pile. Provided so that at least one of the housings can be separated from each other, a restraining member is provided so as to restrain the small cross-sectional portion in the circumferential direction, penetrates through the small cross-sectional portion, and an upper end is formed on the basic housing. It is a PC member used in a method of joining by providing a steel pipe so that the lower end is buried in the head of the pile, and constitutes the concrete in the portion between the steel pipe and the restraining member And formed integrally with the steel pipe and the restraining member.

  According to the present invention, since the small cross-sectional portion has a smaller cross-section than the pile, the bending rigidity is reduced, and further, when a bending load acts between the foundation frame and the pile, the bending load of the small cross-sectional portion As a result of the separation of the portion on the side on which the tensile force acts and the foundation frame or the pile, the tensile force is not transmitted at this portion, so the bending rigidity at the joint between the foundation frame and the pile is reduced. Moreover, since a small cross-sectional part becomes effective in all cross sections with respect to a vertical load compared with the cross section which has the same bending rigidity, it can endure a big vertical load. Furthermore, since the compressive strength of a small cross-section part improves by enclosing a small cross-section part with a restraint member, it can endure.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
Drawing 1 is a figure showing joined structure 10 of a pile and a foundation frame of this embodiment, (A) is a vertical sectional view, (B) is a BB 'sectional view in (A), (C) is. It is CC 'sectional drawing in (A). As shown in the figure, the joint structure of the present embodiment is a structure for joining a building foundation frame 20 and a pile 30 made of cast-in-place concrete piles.

  As shown in the figure, the joining structure 10 includes a first small-diameter portion 40 having a diameter smaller than the diameter of the pile 30 formed between the foundation housing 20 and the pile 30 and surrounding the outer periphery of the small-diameter portion 40. The steel pipe 41 is provided with a second steel pipe 42 that penetrates the small diameter portion 40 and whose both ends are embedded in the foundation frame 20 and the pile 30, respectively.

The foundation frame 20 is a reinforced concrete structure integrally constructed at the lower part of a building (not shown), and a vertical load and a horizontal force are applied from the building.
The pile 30 is composed of concrete 32 placed in an excavation hole formed in the ground, a reinforcing bar 31 embedded in the concrete 32, and a third steel pipe 33 surrounding the head of the pile 30 from the outer periphery. Composed. Since the head of the pile 30 is surrounded by the third steel pipe 33, the third steel pipe 33 restrains the spread when the vertical axial force or the axial compressive force due to the bending load acts on the concrete 34. The compressive strength of concrete 34 is improved. In addition, the third steel pipe 33 can resist the horizontal force borne by the steel pipe 42 penetrating the small diameter portion 40 and the force to be pushed outward due to the bending load.

  A joint surface F exists between the concrete 44 that is surrounded by the first steel pipe 41 and that constitutes a portion corresponding to the outer peripheral portion of the second steel pipe 42 and the concrete 21 that constitutes the foundation frame 20. As a result, the concrete 21 and 44 are separated so as to be separable when a tensile load is applied.

The joining structure 10 of this embodiment can be constructed as follows.
First, a hole is excavated in the ground, a reinforcing bar 31 is built in the excavated hole, and concrete 32 is placed in the hole to construct a cast-in-place concrete pile. Then, as shown in FIG. 2, after the placed concrete 32 is hardened, the upper part of the cast-in-place concrete pile is hung and the upper part of the reinforcing bar 31 is exposed.

  Next, as shown in FIG. 3, the third steel pipe 33 is arranged at the upper part of the cast-in-place concrete pile, the first steel pipe 41 is arranged at a height corresponding to the upper part of the pile 30, and the first steel pipe 41 is arranged. 2nd steel pipe 42 is arranged so that the inside may be inserted. Further, the space between the third steel pipe 33 and the first steel pipe 41 is closed with a mold material 45 such as veneer. In addition, what is necessary is just to support the 1st steel pipe 41 and the 2nd steel pipe 42 in a predetermined height position with a spacer.

  Next, as shown in FIG. 4, concrete is poured from the upper side of the second steel pipe 42 through the inside thereof until the upper surface reaches the upper end of the first steel pipe 41. Thereby, the concrete 34 which comprises the inside of the 3rd steel pipe 33, the concrete 44 which is enclosed by the 1st steel pipe 41, and comprises the part which hits the outer periphery of the 2nd steel pipe 42, and the inside of the 2nd steel pipe 42 are used. The portion up to the height of the lower surface of the concrete foundation frame 20 to be constructed will be cast integrally. Then, it is cured until the concrete placed is cured.

  Next, reinforcing bars constituting the base frame 20 are arranged, and concrete constituting the upper part in the concrete 21 and the second steel pipe 42 constituting the basic frame is placed. Thereby, the joining surface F is formed between the concrete 21 which comprises the foundation frame 20, and the concrete 44 which is enclosed by the 1st steel pipe 41, and comprises the part equivalent to the outer peripheral part of the 2nd steel pipe 42. FIG. The joint structure 10 is constructed by hardening the placed concrete.

The joint part of the foundation frame 20 and the pile 30 having such a configuration needs to be able to transmit a vertical load acting on the foundation frame 20 to the pile 30.
In the present embodiment, a vertical load is transmitted between the foundation frame 20 and the pile 30 via the small diameter portion 40 (range A in FIG. 5), but the concrete 43 and 44 constituting the small diameter portion 40 are The compressive strength of the concrete 43, 44 is improved by being surrounded by the first steel pipe 41 and being restrained from the outside. For this reason, although the small diameter part 40 has a diameter smaller than the pile 30, it can transmit the vertical load which acts on the foundation frame 20 fully.

Moreover, the joint part of the foundation frame 20 and the pile 30 needs to be able to transmit the horizontal force acting on the foundation frame 20 to the pile 30.
On the other hand, in this embodiment, since the 2nd steel pipe 42 has become the state by which the both ends were respectively embed | buried under the foundation frame 20 and the pile 30, it integrated with the 2nd steel pipe 42 and this. A horizontal force can be reliably transmitted between the foundation frame 20 and the pile 30 via the concrete 43 in the second steel pipe 42.

Moreover, in this embodiment, since the small diameter part 40 with a diameter smaller than the pile 30 is interposed between the foundation frame 20 and the pile 30, the rigidity of a pile head is falling. Furthermore, when a bending load acts on the joint part of the foundation frame 20 and the pile 30, the concrete 44 and the foundation frame 20 between the 1st steel pipe 41 and the 2nd steel pipe 42 will be comprised, as shown in FIG. Since the concrete 21 is separated, the tensile force is not transmitted between the foundation frame 20 and the pile 30 in this portion. For this reason, a bending load will be transmitted only by the part of the range B in FIG. 6, and the bending rigidity in the junction part of the foundation frame 20 and the pile 30 will fall.
In addition, when a vertical load or a bending load acts on the joint part of the foundation frame 20 and the pile 30, large vertical stress will act on the head of the pile 30 from the small diameter part 40, but the concrete which comprises a pile head. Since the strength of the concrete 34 is improved by surrounding the 34 with the third steel pipe 33, the stress transmitted from the small diameter portion 40 can be withstood. In addition, since the small-diameter portion 40 is effective for the entire cross section compared to a cross section having the same bending rigidity, it can withstand a large vertical load.

  As explained above, according to this embodiment, since the foundation frame 20 and the pile 30 are connected via the small diameter part 40, the bending rigidity of this part falls, Furthermore, it bends between the foundation frame 20 and the pile 30. When the load is applied, the portion on the side where the tensile force acts due to the bending load of the concrete 44 constituting the small-diameter portion 40 is separated from the foundation housing 20, so that the transmission of the tensile force is not performed in this portion. The bending rigidity in the joint part of 20 and the pile 30 can be reduced.

  Moreover, since the intensity | strength of the concrete 43 and 44 improves by the restraint effect by the 1st steel pipe 41 surrounding the concrete 43 and 44 inside, a vertical load can fully be transmitted.

  In the present embodiment, the concrete 44 constituting the small-diameter portion 40 is surrounded by the second steel pipe 42. However, the present invention is not limited thereto, and may be surrounded by a FRP tubular member. It is good also as a structure which affixes the sheet | seat made on the outer periphery of the concrete 44, and the member which can be restrained from the outside when a compressive load acts on the concrete 44 will be sufficient.

  Similarly to this, in the present embodiment, the third steel pipe 33 is provided so as to surround the outer periphery of the concrete 34 constituting the head of the pile 30. However, the present invention is not limited to this, and the FRP tubular member is used. Alternatively, the FRP sheet may be attached to the outer periphery of the concrete 34. In short, any member that can be restrained from the outside when a compressive load is applied to the concrete 34 may be used.

  Moreover, in this embodiment, it was set as the structure which provides the 3rd steel pipe 33 so that the outer periphery of the head of the pile 30 may be surrounded, However, Not only this but the concrete 34 which comprises a pile head is made into high strength concrete. Thus, the third steel pipe 33 can be omitted.

  Moreover, in this embodiment, although the concrete 44 which comprises the small diameter part 40 shall be constructed | assembled by on-site strike, you may use not only this but PC member. When such a PC member is used, the first steel pipe 41 and the second steel pipe 42 may be attached to the annular PC member constituting the concrete 44 constituting the small-diameter portion 40 in the field. 7, a PC member 100 that is integrated with the first steel pipe 41 and the second steel pipe 42 may be used.

  Moreover, in this embodiment, by providing a joint surface between the upper surface of the concrete 44 constituting the small-diameter portion 40 and the concrete 21 constituting the foundation frame 20, the concrete 21 and 44 are separated so as to be separated from each other. However, the present invention is not limited to this, and the edge may be cut by interposing a vinyl sheet or a plate material between the concrete 21 and 44.

  In addition, the portion to be separated in such a manner as to be separable may be provided between the concrete 44 constituting the small diameter portion 40 and the concrete 34 constituting the pile 30. In addition, when providing the part to cut edge between the concrete 44 which comprises the small diameter part 40, and the concrete 34 which comprises the pile 30, the concrete 34 which comprises the head of the pile 30 is laid, and this concrete 34 Is hardened, the concrete 44 constituting the portion between the first steel pipe 41 and the second steel pipe 42 and the concrete 21 constituting the foundation frame 20 may be handed over.

  Further, when the small-diameter portion 40 is constructed using a PC member as described above, the PC steel wire is embedded in the annular concrete 44 constituting the outer portion of the second steel pipe 42 of the small-diameter portion 40. By doing so, the concrete 44 can be restrained similarly to the first steel pipe 41.

  Moreover, in this embodiment, it was set as the structure which transmits a horizontal force between the foundation frame 20 and the pile 30 by the concrete 43 inside the 2nd steel pipe 42 and the 2nd steel pipe 42, but also 2nd Reinforcing bars may be embedded so as to penetrate the inside of the steel pipe 42 and both ends thereof are embedded in the foundation frame 20 and the pile 30, and a part of the horizontal force may be transmitted by the reinforcing bars.

  Moreover, in this embodiment, although the case where the pile 30 was a circular cross section was demonstrated, not only this but the case where the pile 30 and the foundation frame 20 of cross sections of other shapes, such as a rectangle, are connected, for example. Can also be applied. In such a case, the pile 30 and the foundation frame 20 may be connected by a member having a smaller cross section than the pile.

It is a figure which shows the joining structure of the pile of this embodiment, and a foundation frame, (A) is a vertical sectional view, (B) is BB 'sectional drawing in (A), (C) is C in (A). It is -C 'sectional drawing. It is a vertical sectional view (the 1) for explaining the method of constructing the joined structure of the pile of this embodiment, and the foundation frame. It is a vertical sectional view (the 2) for explaining the method of constructing the junction structure of the pile of this embodiment, and a foundation frame. It is a vertical sectional view (the 3) for explaining the method of constructing the junction structure of the pile of this embodiment, and the foundation frame. It is a vertical sectional view which shows the range which transmits the vertical load which acts on the foundation frame in the joining structure of this embodiment. It is a vertical sectional view showing a state where a bending load is applied to the joint structure of this embodiment. It is a perspective view which shows the PC member united with the 1st and 2nd steel pipe.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Joining structure 20 Foundation frame 21, 32, 34, 43, 44 Concrete 30 Pile 31 Reinforcing bar 33 3rd steel pipe 40 Small diameter part 41 1st steel pipe 42 2nd steel pipe

Claims (4)

It is a joint structure between a concrete pile and a foundation frame,
A small cross section formed between the pile and the foundation frame, the cross section is smaller than the cross section of the pile, and at least one of the pile or the foundation frame is edged so as to be separable;
A restraining member for restraining the small cross section in the circumferential direction;
A steel pipe penetrating through the small cross section, the upper end being embedded in the foundation frame, and the lower end embedded in the head of the pile;
A structure for joining a pile and a foundation frame characterized by comprising: The joint structure of the pile according to claim 1 and the foundation frame,
A joint structure for a foundation frame comprising a second restraining member for restraining the upper part of the pile in the circumferential direction. A method for joining a concrete pile and a foundation frame,
Between the pile and the foundation frame, a small cross-section is provided so that the cross-section is smaller than the cross-section of the pile so that at least one of the pile or the foundation frame can be separated.
A restraining member is provided so as to restrain the small cross section in the circumferential direction,
A method for joining a pile and a foundation frame, characterized in that a steel pipe is provided so as to penetrate the inside of the small cross-section part, the upper end is embedded in the foundation frame, and the lower end is embedded in the head of the pile. A concrete pile and a foundation frame, between the pile and the foundation frame, a small cross section having a smaller cross section than the cross section of the pile, between the pile or at least one of the foundation frames. Provided so as to be separated from each other, provided with a restraining member so as to restrain the small cross section in the circumferential direction, penetrated through the small cross section, the upper end is embedded in the foundation frame, and the lower end is the head of the pile A PC member used in a method of joining by providing a steel pipe so as to be embedded in
A PC member comprising a portion of concrete between the steel pipe and the restraining member and integrally formed with the steel pipe and the restraining member.

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