JP2000303483A - Foundation structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lessen a bending moment to be generated in a support pile by a horizontal load by supporting a building erected on a soft ground by support piles connected to a foundatin slab with pins and filling a buffer material in between steel pipe piles driven so as to cover the upper outer periphery of the support piles and the support piles. SOLUTION: A building 2 erected on a soft ground has a structure in which a foundation slab 6 composed of a footing 4 and foundation beams 5 is supported by support piles 8 driven in the supporting ground 7. The support pile 8 is connected to the footing 4 with pins and is freely deformable around the part connected by the pin. Further, the outer periphery of the pile head 10 is protected by steel pipe piles 11 and a buffer material 12 is filled between the steel pipe piles 11 and the support piles 8. When a horizontal load acts due to an earthquake or the like, the support pile 8 is rotationally deformed around the pin-connection part in the steel pipe pile 11 and a bending moment brought in the pile head 10 is lessened. As a result, since a sear force acting on the foundation beam 5 is lessened as well, the sectional area of the foundation beam 5 can be decreased. Further, since the steel pipe pile 11 functions as a horizontal resistance pile, it resists a horizontal load and attenuate it.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a basic structure.

[0002]

2. Description of the Related Art A reinforced concrete building or the like generally constructed on soft ground is supported by a pile 17 such as a concrete pile or a steel pipe pile as shown in FIG. The pile 17 is driven into the supporting ground 19 located below the soft ground 18 to support the vertical load of the building 20.

[0003]

However, the above-mentioned pile is uneconomical because it has a large cross section capable of supporting a vertical load and sufficiently withstanding a horizontal load due to an earthquake or the like.

The present invention has been made in view of the above problems, and an object of the present invention is to make the diameter of a pile supporting a building constructed on the ground as small as possible.

[0005]

According to a first aspect of the present invention, a building constructed on soft ground is supported by a support stake which is pin-joined to a foundation slab. A steel pipe pile is cast so as to cover an upper outer periphery of the support pile, and a buffer material is filled between the steel pipe pile and the support pile.

According to the first aspect of the present invention, since the support pile is pin-joined to the foundation slab, the bending moment generated in the support pile due to a horizontal load such as an earthquake can be reduced. In addition, the support pile is not restrained by the soft ground, and rotationally deforms around the pin joint in the steel pipe pile to attenuate the horizontal load. In addition, steel pipe piles protect the upper periphery of the support piles.

A second aspect of the present invention is characterized in that, in the first aspect, a horizontal resistance pile is provided on a foundation slab around the support pile.

According to the second aspect of the present invention, the horizontal resistance pile acts on the pile head by dissipating the seismic energy using the ground reaction force and the ground attenuation generated when the horizontal resistance pile moves horizontally in the soft ground. Since the bending moment can be reduced, the diameter of the support pile can be reduced to a size that can support only the vertical load. In addition, since the support pile is deformed around the pin joint without being restrained by the soft ground, the horizontal force can be effectively shared to the horizontal resistance pile.

The invention of claim 3 is the first or second invention.
Wherein the horizontal resistance pile is prestressed by a tendon material.

According to the third aspect of the invention, the prestressed is applied to the horizontal resistance pile and a certain amount of axial force acts thereon, thereby increasing the strength of the horizontal resistance pile.

According to a fourth aspect of the present invention, in any one of the first to third aspects, the horizontal resistance pile has a circular cross section or a polygonal cross section.

According to the fourth aspect of the present invention, the cross-sectional shape of the horizontal resistance pile can be adapted to the shape of the building and the properties of the ground.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the foundation slab includes a footing and a foundation beam.

According to the fifth aspect of the present invention, the bending moment generated at the pile head due to the pin connection of the supporting pile,
Since the shearing force of the foundation beam can be reduced, the cross section of the foundation beam can be reduced.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the basic structure according to the present invention will be described below in detail with reference to the drawings. FIG. 1 is a cross-sectional view of the basic structure according to the first embodiment, and FIG.
3 is an enlarged sectional view of a main part, and FIG. 4 is an enlarged sectional view of a pile head.

FIG. 1 shows a soft ground 1 with no ground improvement.
1 shows a foundation structure 3 of a building 2 constructed above, in which a foundation slab 6 composed of a footing 4 and a foundation beam 5 is supported by a support pile 8 cast on a support ground 7.

The supporting pile 8 is a cast-in-place reinforced concrete pile,
Or, it is an existing reinforced concrete pile, as shown in FIG. 4, which is pin-joined to the footing 4 so that it can be freely rotated and deformed around the pin joint 9. The outer periphery of the pile head 10 is protected by a steel pipe pile 11, and a cushioning material 12 such as sand or an elastic body is provided between the steel pipe pile 11 and the support pile 8.
Is filled. Therefore, the support pile 8 (hereinafter, referred to as a horizontal load) is rotationally deformed around the pin joint 9 in the steel pipe pile 11 by a horizontal load such as an earthquake, so that a bending moment generated in the pile head 10 is reduced. Further, since the steel pipe pile 11 also serves as a horizontal resistance pile, it also resists a horizontal load.

FIGS. 5 and 6 show a basic structure 13 according to the second embodiment, in which a horizontal resistance pile 14 is provided on a footing 4 around a steel pipe pile 11. Other configurations provided are the same as those of the first embodiment. The horizontal resistance pile 14 resists a horizontal load,
It is formed by precast concrete or cast-in-place concrete to a length that allows horizontal movement in the soft ground 1. The horizontal resistance pile 14 is not limited to the footing 4 and may be provided on any of the foundation slabs 6.

As described above, the basic structure 13 is intended to attenuate a horizontal load by using the soft ground 1 as a natural damping material. That is, the horizontal load is reduced by utilizing the ground reaction force generated by the horizontal resistance pile 14 moving horizontally in the soft ground 1 and the ground attenuation. Since the bending moment acting on the pile head 10 can be reduced by this, the diameter of the support pile 8 can be reduced to a size that can support only the vertical load. Further, when the bending moment is reduced, the shearing force acting on the footing 4 is also reduced, so that the footing 4 itself can be reduced.

The support pile 8 is rotated around the pin joint 9 to attenuate the horizontal load. The damping effect is further enhanced by the cushioning material 12 between the support pile 8 and the steel pipe pile 11. Accordingly, the soft ground 1 and the pin-supported support pile 8
And the horizontal resistance piles 14 to form the basic structure 13 capable of flexibly responding to a horizontal load.

FIG. 7 shows a basic structure 15 according to a third embodiment, in which a horizontal resistance pile 14 is prestressed by a tension member 16 such as a PC steel wire or a PC steel bar, and this point is excluded. Other configurations are the same as those of the second embodiment.

The horizontal resistance pile 14 is not limited to a circular cross section, but may be a rectangular cross section or another polygon.
The length, the number, the ratio of the length to the support pile 8 and the like are determined according to the size, shape, structure type, or property of the ground of the building 2 (not shown).

[0023]

As the bending moment acting on the support pile is reduced, the shearing force acting on the foundation beam is also reduced, so that the cross section of the foundation beam can be reduced.

Since the steel pipe pile also serves as a water bottom resistance pile, it can be attenuated by resisting even a horizontal load.

The support pile not restrained by the soft ground rotates and deforms around the pin joint in the steel pipe pile to attenuate the horizontal load, and the damping effect is further enhanced by the cushioning material.

The upper periphery of the support pile can be protected by a steel pipe pile.

The bending moment generated at the pile head can be reduced by dissipating the seismic energy by using the ground reaction force and the ground attenuation generated by the horizontal resistance pile moving horizontally in the soft ground, so that the supporting pile can be reduced. Can be reduced to a size that can support only a vertical load. In addition, since the supporting pile is not restricted by the soft ground and is rotated around the pin joint in the steel pipe pile, horizontal force can be effectively shared to the horizontal resistance pile.

The prestressing is applied to the horizontal resistance pile, and a certain amount of axial force acts thereon, so that the strength of the horizontal resistance pile can be increased.

The cross-sectional shape of the horizontal resistance pile can be adapted to the shape of the building and the properties of the ground.

By using the soft ground as a natural damping material, it is possible to save time and effort for improving the ground, thereby shortening the construction period and reducing the construction cost.

By using the soft ground as a natural damping material, the horizontal load can be effectively damped.

[Brief description of the drawings]

FIG. 1 is a sectional view of a basic structure.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is an enlarged sectional view of a main part of the basic structure.

FIG. 4 (1) is an enlarged sectional view of a pile head, and (2) is (1).
FIG. 3 is a sectional view taken along line BB of FIG.

FIG. 5 is a sectional view of a basic structure according to a second embodiment.

FIG. 6 (1) is an enlarged sectional view of a pile head, and (2) is (1).
It is CC sectional view taken on the line of FIG.

FIG. 7 is an enlarged sectional view of a pile head in a foundation structure according to a third embodiment.

FIG. 8 is a sectional view of a conventional basic structure.

[Explanation of symbols]

 1,18 Soft ground 2,20 Building 3,13,15 Foundation structure 4 Footing 5 Foundation beam 6 Foundation slab 7,19 Support ground 8 Support pile 9 Pin joint 10 Pile head 11 Steel pipe pile 12 Buffer material 13 Foundation structure 14 Horizontal resistance pile 16 Tensile material 17 pile

Claims (5)

[Claims] 1. A building constructed on soft ground is supported by a support pile that is pin-joined to a foundation slab, and a steel pipe pile is cast so as to cover an upper outer periphery of the support pile. A basic structure characterized by filling cushioning material between the piles. 2. The foundation structure according to claim 1, wherein a horizontal resistance pile is provided on the foundation slab around the support pile. 3. The foundation structure according to claim 1, wherein the horizontal resistance pile is prestressed by a tendon material. 4. The foundation structure according to claim 1, wherein the horizontal resistance pile has a circular cross section or a polygonal cross section. 5. The foundation structure according to claim 1, wherein said foundation slab comprises a footing and a foundation beam.