JP2003027498A - Support structure for foundation of structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a support structure for the foundation of a structure, which is capable of easily adjusting the degree of fixation of a pipe head portion and of securing ease and speed of construction work. SOLUTION: This support structure for the foundation of a structure, supports the foundation of the structure (footing foundation 2) while placing the foundation of the structure (footing foundation) on the top of the pile head portion 1a at a bearing pressure portion 2a, including the pile head portion 1a and the bearing pressure portion 2a provided by protruding downward from the bottom surface of the foundation of structure (footing foundation 2), and the bearing pressure portion 2a is the support structure, having a shape of a reversed head-cut circular cone.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a support structure for a structure foundation used when there are piles between the structure foundation and the supporting ground.

[0002]

2. Description of the Related Art Conventionally, FIG. 3 (FIG. 3 (a) is a cross-sectional view, FIG. 3 (b) is a C direction in FIG. 3 (a) as a support structure of a structure foundation developed by the present applicants. Pile head 1 of cast-in-place concrete pile 101
01a and a bearing portion 101c having a truncated cone shape provided as a reinforced concrete structure on the pile head 101a.
There is a method of supporting the base 102 while placing it on the bearing portion 101c.

According to such a support structure for a structural foundation, the load of the foundation 102 is received only by placing the foundation 102 on the cast-in-place concrete pile 101, whereby the degree of fixation of the pile head is improved. Even if the cast-in-place concrete pile 101 or the foundation 102 receives a large horizontal force due to an earthquake or the like, the cast-in-place concrete pile 10
It is possible to enjoy the effect of being able to reduce the bending moment or the like that occurs in No. 1 or the foundation 102.

[0004]

However, in such a support structure for a structure foundation, it is necessary to perform a hanging process on the pile head 101a to produce the bearing portion 101c having a truncated cone shape. There are the following problems.

That is, the bearing portion 10 having a truncated cone shape.
In order to make 1c, apart from the chipping process for removing the extra pile of the pile head 101a, which is performed in the range 121 that does not reach the original positions of the main bar 111 and the stirrup 112, the pile head 1 is exclusively used.
In order to form 01a in the shape of a truncated cone, a hanging process is performed in a range 122 that extends to the positions of the main bars 111 and the stirrups 112, and then a formwork is installed in the part where the hanging process is performed, and there is more strength than the pile main body 101b. It is necessary to perform a very complicated and time-consuming operation of placing high concrete. Here, from the pile main body 101b to the bearing portion 101
It is the pile body 101 that increases the concrete strength of c.
This is because the bearing portion 101c having an area smaller than the cross-sectional area of b receives the load from the foundation 102, so that a considerably large bearing stress acts on the bearing portion 101c having a truncated cone shape. In particular, in such a chipping treatment work, since the pile diameter cannot be made uniform due to the characteristics of the cast-in-place concrete pile 101, it is extremely complicated.

Further, as a method of eliminating such a complicated field work, the bearing portion 101c having a truncated cone shape is formed.
Although a method of precasting the pressure-bearing portion 101c may be considered, even if the complexity of manufacturing the pressure-bearing portion 101c is eliminated by the precasting, the pressure-bearing portion 101 made of precast material
In order to integrate c into the pile head 101a, the pile head 101
In the end, almost the same work as in the case where the pressure bearing portion 101c is not precast is required, such as the chipping treatment of a and the placement of concrete for integration.

[0007] Therefore, an object of the present invention is to provide a support structure for a structure foundation which makes it possible to easily adjust the degree of fixation of the pile heads and to ensure the ease and speed of construction. To provide.

[0008]

That is, the structure for supporting a structure foundation according to the present invention includes a pile head and a bearing portion having an inverted frustum shape provided so as to project downward from the bottom surface of the structure foundation. The structure foundation is supported while being placed on the pile head at the bearing portion. Here, the inverted frustum shape includes not only a shape in which the cross-sectional area monotonously decreases as it goes downward, but also a shape in which a part thereof has a constant cross-sectional area. It is a waste.

According to the support structure for a structure foundation according to the present invention, it is possible to avoid extremely complicated and time-consuming work such as chipping of the pile head and placing of concrete, which are required separately from the original pile construction. Therefore, the ease and speed of construction can be ensured, and the degree of fixation of the pile head can be easily adjusted. Therefore, even if a large horizontal force is applied, the bending moment generated in the pile or the structural foundation can be reduced, and the reinforcing bar for the bending moment can be reduced.

In such technical means, the structure foundation which is the object to be supported is a concept that includes all foundation structures that can be supported by piles, regardless of construction or civil engineering. Not limited to footing foundations and mat foundations, it includes all members located at the bottom of the building as long as the structure is directly supported by piles.

There are no particular restrictions on the type of pile that supports such a structural foundation, whether it is a support pile or a friction pile, steel piles such as ready-made piles, concrete piles, etc. It doesn't matter whether they are used or cast in place.

It should be noted that the pile head does not require any special treatment other than the chipping treatment for removing the extra deposit, but it is intended to ensure sufficient strength to withstand a large bearing pressure applied to the pile head. From a point of view, compared to the normal case,
It is preferable to arrange the band reinforcements for shear reinforcement densely.

Further, "mounting" means that the structure of supporting the structure foundation by the pile head is only that the structure foundation is mounted on the pile head at the bearing portion, and the bearing portion and the pile are mounted. It means that the edge with the head is cut off. Therefore, when the lower portion of the bearing portion is buried in the pile head and the edges of both are not cut, the placement here does not apply.

Here, as a pile head, it is preferable that the pile head is in a closed state without a hollow portion in principle for the purpose of placing concrete of the structure foundation after the pile concrete is placed, but there is a hollow portion. However, it can be dealt with by placing the filling concrete or by covering the top of the pile.

On the other hand, the bearing portion is provided so as to project downward from the bottom surface of the structure foundation, and if the structure has strength enough to support the structure foundation by the pile heads, the structure foundation portion. However, the present invention is not limited to the above, and includes a member that is a member independent of the structure foundation.

Therefore, as the bearing portion, for example, one made only of cast-in-place concrete, one made of only steel material, and one partially containing concrete,
It can be appropriately selected and used according to the external force or the magnitude of the vertical load. When the pile is a cast-in-place pile, it is preferable that the strength of the bearing portion is higher than the strength of the pile.

However, it is preferable that the bearing portion is made of a precast member from the viewpoint of further improving the easiness and speed of the construction by reducing the construction on site as much as possible.

In this case, from the viewpoint of ensuring sufficient strength to withstand a large compressive force received from the pile and the structural foundation, the bearing portion is made of a steel material arranged at the outer edge portion. It is preferable.

In order to prevent the outer peripheral end of the bearing portion from being chipped, the outer peripheral end may be chamfered or the upper surface may be spherical.

Further, from the viewpoint of resisting the pulling force between the pile and the structure foundation, the pile head has a core steel material (core rebar or the like) fixed to the structure foundation through the bearing portion.
Is preferably provided.

It is to be noted that the provision of the core steel material for transmitting the pulling force and the horizontal force between the pile and the structure foundation through the bearing portion is
It does not prevent the above-mentioned mounting method of supporting the structure foundation by the pile head.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

First Embodiment FIG. 1 is a diagram showing a schematic configuration of a structure support structure for a first embodiment of the present invention in service (FIG. 1 (a) is a sectional view, FIG. 1 (b)). Is a view from the direction of arrow A in FIG.
Is.

The following description is of a structure for supporting a structure foundation using cast-in-place concrete piles as a pile, but a structure for supporting a structure foundation using a pile other than a cast-in-place concrete pile. Is also relevant. In addition, the structural foundation is valid for footing foundations and other types of foundations.

In the first embodiment, the cast-in-place concrete pile 1 is, as shown in FIG. 1 (a), a pile main body 1b whose tip reaches the support layer and an upper side adjacent to the pile main body 1b. It is composed of the pile head 1a located at.

As shown in FIG. 1, the support structure for the structure foundation is to support the foundation 2 while placing it on the pile head 1a at the bearing portion 2a. It is composed of one pile head portion 1a and a bearing portion 2a provided under the foundation 2 and integrally therewith. Hereinafter, each component will be described in detail.

(1) Pile head 1a As shown in FIG. 1 (a), the pile head 1a is the upper end portion of the cast-in-place concrete pile 1 that receives the load from the foundation 2 and is adjacent to the pile body 1b. It is the part located on the upper side. However, the pile head 1a does not include a portion which is removed by the method by the chipping method, although it is temporarily present as an extra portion including slime immediately after the cast-in-place concrete pile 1 is placed as underwater concrete.

Here, on the outer peripheral portion of the pile head portion 1a, as shown in the figure, a reinforcing bar cage 10 for ensuring the strength as a pile foundation is arranged. And this rebar cage 10
In the portion of the pile head portion 1a, the band reinforcement 12 for shear reinforcement is densely arranged as compared with the pile main body portion 1b.
This is a bearing portion 2a having an area smaller than the cross section of the pile body portion 1b.
Since the load from the foundation 2 is received by the above, a considerably large bearing stress acts on the pile head 1a, and it is necessary to prevent the pile head 1a from being broken by this.

The rebar cage 10 is not fixed to the foundation 2 and does not interfere with the method of supporting the foundation 2 by the pile heads 1a.

(2) Bearing portion 2a As shown in FIG. 1, the bearing portion 2a is a portion provided so as to project downward from the bottom surface of the foundation 2 and is placed directly on the pile head 1a. It is the part that is.

As shown in the figure, the bearing portion 2a has a lower end surface which is in contact with the top surface of the pile head 1a, which is a substantially horizontal surface, within the range of the top surface, and is fixed below the foundation 2. The upper end surface is wider than the lower end surface and is within the lower region of the lower end surface.

In the first embodiment, as shown in the figure, the area of the upper end surface is substantially the same as the area of the top surface of the pile head 1a, and the area of the lower end surface is smaller than the area of the upper end surface. It has a truncated cone shape.

As shown in the figure, the bearing portion 2a receives the load from the foundation 2 on the lower end surface having a smaller area than the upper end surface, so that it can resist a large compressive force. Must have sufficient strength.

Therefore, in the first embodiment, the bearing portion 2
The concrete compressive strength of "a" is determined in consideration of the compressive force and the horizontal force that the bearing portion 2a receives.

Here, the degree of smoothness at the lower end surface of the bearing portion 2a is such that a horizontal force can be transmitted by the frictional force generated between the bearing portion 2a and the pile head 1a.

The bearing portion 2 according to the first embodiment
Although not shown, a modified example of a may be an inverted truncated pyramid shape having a polygonal shape in a plan view.

When such an inverted truncated pyramid shape is used, since the bearing portion 2a receives a large compressive force, the lower end surface of the bearing portion 2a is a substantially horizontal surface of the pile head 1a. Must be within the range.

Specifically, the pile head 1a having a circular shape.
Must be smaller than the polygon inscribed on the top surface of.

Next, with reference to FIG. 1, a method of constructing a support structure for a structure foundation according to the first embodiment will be described.

First, after pouring the cast-in-place concrete pile 1, the pile head 1a is subjected to a chipping treatment in order to remove the extra pile of the pile head 1a. The chipping process at this time is performed by the pressure bearing portion 2a.
The pile head 1a has a structure in which the pile is placed on the pile head 1a.
Since there is no rebar cage 10 in the surplus, the original main bar 1
It can be easily performed within a range that does not take up to the position of 1 or the stirrup 12, and it does not take much time.

Then, when the top surface of the pile head 1a is finished to be a substantially horizontal surface, the chipping process of the pile head 1a is completed.

Subsequently, while the area excluding the pile head 1a is backfilled with good quality soil, the compaction is performed, and the crushed foundation stone is leveled and compacted according to the height of the bottom surface of the foundation 2. Next, leveling concrete is poured.

At this time, the periphery of the pile head 1a is formed in a serrated shape so that the portion serving as the bearing portion 2a has an inverted truncated cone shape.

Next, with respect to the portion of the pressure bearing portion 2a included in the foundation 2, a formwork is erected and the reinforcing bars are assembled, and then,
The concrete of the bearing portion 2a is placed.

In the first embodiment, since the concrete compressive strength of the bearing portion 2a of the foundation 2 is set to be considerably higher than that of the portion other than the bearing portion 2a, the concrete of the bearing portion 2a and the bearing portion 2a are set. It is to be constructed separately from the concrete other than 2a.

Next, after the concrete curing period of the bearing portion 2a has elapsed, the reinforcing bars and the formwork are assembled with respect to the portion of the foundation 2 other than the bearing portion 2a, and then the bearing portion 2a is assembled.
Place the concrete in the other areas.

Then, after the curing period of the concrete of the portion other than the bearing portion 2a has passed, the construction of the support structure for the structure foundation is completed.

Next, the operation of the support structure for the structure foundation according to the first embodiment will be described with reference to FIG.

First, when an earthquake occurs, on the one hand, the cast-in-place concrete pile 1 integrated with the ground vibrates in response to the vibration of the ground, and on the other hand, the foundation 2 also vibrates via the cast-in-place concrete pile 1. To do.

At this time, since the cast-in-place concrete pile 1 and the foundation 2 have different natural periods, they try to vibrate independently. Then, since a frictional force is generated between the pile head portion 1a and the bearing portion 2a, the cast-in-place concrete pile 1 and the foundation 2 are subjected to horizontal forces with each other.

However, in the support structure for the foundation of this structure, the foundation 2 and the pile head 1a have a large degree of rotational freedom and a low degree of fixing, and the foundation 2 supports the pile head 1a at the bearing portion 2a. The structure is just placed on top.

Further, the load from the foundation 2 is received by the lower end surface of the bearing portion 2a having an area smaller than the area of the top surface of the pile head 1a.

Therefore, even when the cast-in-place concrete pile 1 and the foundation 2 receive such a large horizontal force, the bending moment acting on the cast-in-place concrete pile 1 and the foundation 2 can be reduced.

As described above, according to the support structure for a structure foundation according to the first embodiment, apart from the original construction of cast-in-place concrete pile 1, chipping of the pile head 1a and placing of concrete are carried out. It has become possible to avoid the extremely complicated and time-consuming work such as.

Therefore, the fixing degree of the pile head can be easily adjusted, and even if a large horizontal force is applied,
While maintaining the effect of reducing the bending moment acting on the cast-in-place concrete pile 1 and the foundation 2, it is possible to secure the easiness and speed of construction at the same time.

Second Embodiment FIG. 2 is a diagram showing a schematic configuration of a structure foundation support structure according to a second embodiment of the present invention in service (FIG. 2 (a) is a sectional view, FIG. 2 (b)). Is a view in the direction of arrow B in FIG. 2 (a))
Is. The same components as those in the first embodiment are designated by the same reference numerals as those in the first embodiment, and the detailed description thereof is omitted here.

The basic structure of the structure foundation support structure is substantially the same as that of the first embodiment, but unlike the first embodiment, as a type of pile for supporting the foundation 2, a band for shear reinforcement is used. The steel pipe concrete pile 3 in which the hollow portion of the steel pipe pile 3a that does not require the reinforcement 12 is filled with concrete 3b is adopted, and in addition, the bearing portion 2a is provided on the outer edge portion of the precast concrete block 4a which is the precast member. The steel pipe-wound precast concrete 4 is provided by disposing the steel pipe 4b as a steel material.

Therefore, according to the structure supporting structure of the second embodiment, the precast concrete block 4a is used for the bearing portion 2a.
On-site construction can be simplified and the ease and speed of construction can be further improved, and the steel pipe wound precast concrete 4 in which the steel material 4b is arranged on the outer edge of the precast concrete block 4a is used. Therefore, it is possible to secure sufficient strength to withstand a large compressive force received from the steel pipe concrete pile 3 and the foundation 2.

Although the precast concrete block 4a has a chamfered outer peripheral end, this has an effect of preventing the outer peripheral end of the bearing portion 2a from being chipped.

[0060]

According to the support structure for a structure foundation according to the present invention, the degree of fixing of the pile head can be easily adjusted, and the ease and speed of construction can be ensured. .

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of a support structure for a structure foundation according to Embodiment 1 of the present invention when in service (FIG. 1 (a) is a sectional view, FIG. 1 (b) is FIG. 1 (a)). It is an A direction arrow view).

FIG. 2 is a diagram showing a schematic configuration of a structure supporting structure for a structure according to Embodiment 2 of the present invention when in service (FIG. 2 (a) is a sectional view, FIG. 2 (b) is FIG. 2 (a)). It is an A direction arrow view).

FIG. 3 is a diagram showing a schematic configuration of a conventional structure foundation support structure in service (FIG. 3 (a) is a sectional view, FIG.
3B is a view as seen from the direction of arrow A in FIG.

[Explanation of symbols]

1… Cast-in-place concrete pile 1a ... Pile head 1b ... Pile body 2 ... Foundation (structure foundation) 2a ... pressure bearing 3 ... Steel pipe concrete pile 3a ... Steel pipe pile 3b ... concrete 4 ... Steel pipe wound precast concrete (bearing part) 4a ... Precast concrete block 4b ... Steel pipe (steel material) 10 ... Rebar cage 11 ... Main story 12 ... stirrup 101 ... Cast-in-place concrete pile 101a ... Pile head 101b ... Pile main body 101c ... pressure bearing 102 ... Basic 111 ... Main story 112 ... obi 121 ... range 122 ... range

Continued front page    F-term (reference) 2D041 AA01 BA19 BA37 CA01 CB05                       DA03 EB10                 2D046 CA03 DA11

Claims (2)

[Claims] 1. A pile head and a bearing portion having an inverted frustum shape provided so as to project downward from the bottom surface of the pile foundation, and the structure foundation is placed on the pile head at the bearing portion. A structure-based support structure characterized by supporting while supporting. 2. The support structure for a structural foundation according to claim 1, wherein the bearing portion is made of a precast member.