JP3749675B2 - Support structure for structure foundation - Google Patents

Description

[0001]
[Field of the Invention]
The present invention relates to a support structure for a structure foundation used when there is a pile between the structure foundation and a support ground.
[0002]
[Prior art]
FIG. 3 (FIG. 3 (a) is a cross-sectional view, FIG. 3 (b) is a view in the direction of the arrow C in FIG. 3 (a)) as a support structure for a structure foundation developed by the present applicants. As shown, a pile head 101a of a cast-in-place concrete pile 101 and a bearing section 101c having a truncated cone shape provided as a reinforced concrete structure on the pile head 101a are provided, and the foundation 102 is supported by the bearing section 101c. There is something to support while being placed on top.
[0003]
According to such a structure foundation support structure, the pile head is fixed by placing the foundation 102 on the cast-in-place concrete pile 101 so as to receive the load from the foundation 102. Even when the cast-in-place concrete pile 101 or the foundation 102 receives a large horizontal force due to an earthquake or the like, it is possible to enjoy the effect that the bending moment generated in the cast-in-place concrete pile 101 or the foundation 102 can be reduced. Become.
[0004]
[Problems to be solved by the invention]
However, such a structure foundation support structure has the following problems because it is necessary to carry out the suspension process of the pile head 101a to produce the pressure bearing part 101c having a truncated cone shape.
[0005]
That is, in order to make the bearing section 101c having a truncated cone shape, apart from the lifting process for removing the pile head 101a in the range 121 that does not reach the position of the main main bar 111 or the band bar 112, For the purpose of forming the pile head portion 101a exclusively in the shape of a truncated cone, the suspension processing is performed in the range 122 up to the position of the main reinforcement 111 and the band reinforcement 112, and then the formwork is installed in the processed portion, and the pile main body 101b It is necessary to perform a very complicated and time-consuming work of placing concrete with higher strength. Here, the concrete strength of the bearing part 101c is higher than the pile body part 101b because the bearing part 101c having a smaller area than the cross-sectional area of the pile body part 101b receives the load from the foundation 102. This is because a considerably large bearing stress acts on the bearing section 101c having a truncated cone shape.
In particular, in such a suspension processing work, because the pile diameter cannot be made uniformly due to the characteristics of the cast-in-place concrete pile 101, it becomes extremely complicated.
[0006]
In addition, as a method of eliminating such complicated work on the site, a method of precasting the pressure bearing portion 101c having a truncated cone shape is also conceivable, but the complexity in the production of the pressure bearing portion 101c is temporarily eliminated by precasting. Even if it is done, in order to integrate the precast bearing section 101c into the pile head 101a, the bearing section 101c will eventually be precast, such as the suspension treatment of the pile head 101a or the placement of concrete for integration. It is necessary to perform substantially the same work as in the case of not making it.
[0007]
Then, the subject of this invention provides the support structure of a structure foundation which can ensure the ease of construction and quickness while being able to adjust the fixing degree of a pile head easily. There is.
[0008]
[Means for Solving the Problems]
That is, the support structure of the structure underlying the present invention, pile head, and includes a bearing capacity portion is a reverse frustum shape is provided to protrude downward from the bottom surface of the structure foundation, said structure foundation said supporting The pressure portion is supported while being placed on the top surface of the substantially horizontal pile head . Here, the inverted frustum shape includes not only a shape in which the cross-sectional area decreases monotonously as it goes downward, but also a shape in which a part of the cross-sectional area is constant.
[0009]
According to the support structure of the structure foundation according to the present invention, since it is possible to avoid very complicated and time-consuming work such as hanging of the pile head and placing concrete, which is necessary separately from the original pile construction, It becomes possible to ensure the easiness and quickness of construction, and furthermore, the fixing degree 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 structure foundation can be reduced, and the reinforcing bars for the bending moment can be reduced.
[0010]
In such technical means, the structure foundation that is a supported object is a concept that encompasses all foundation structures that can be supported by piles, regardless of whether they are architecture or civil engineering. It is not limited to a mat foundation, but includes all members located at the bottom of the building as long as the structure is directly supported by a pile.
[0011]
In addition, as the type of pile that supports such a structure foundation, there is no particular restriction, whether it is a support pile or a friction pile, or a steel pile, a concrete pile, etc. that are ready-made piles, It doesn't matter whether it is a cast in place.
[0012]
Note that the pile head does not require any special treatment other than the suspending treatment for removing the extra pile, but it is not necessary to ensure sufficient strength to resist the large bearing pressure that the pile head receives. For example, it is preferable to arrange the reinforcing streaks densely as compared with the normal case.
[0013]
Furthermore, the term “mounting” means that the structure foundation is supported by the pile head only when the structure foundation is placed on the pile head in the bearing section. It means that the edge of is cut. Therefore, when the lower part of the bearing section is buried in the pile head and the edges of both are not cut, it does not correspond to the placement described here.
[0014]
Here, as the pile head, for the convenience of placing the concrete of the foundation of the structure after placing the pile concrete, in principle it is preferably a closed state without a hollow part, but even if there is a hollow part, This can be dealt with by placing medium-filled concrete or by covering the top of the pile.
[0015]
On the other hand, as the bearing part, it is provided to protrude downward from the bottom surface of the structure foundation, and if it has enough strength to support the structure foundation by the pile head, it is a part of the structure foundation It is not limited to, but also includes a member that is a member independent of the structure foundation.
[0016]
Therefore, as the bearing part, for example, one made only of cast-in concrete, one made only of steel, or one partially containing concrete is selected as appropriate according to the external force, vertical load, etc. Can be used.
In addition, when a pile is used as a cast-in-place pile, it is preferable to make the strength of a bearing part higher than the strength of a pile.
[0017]
However, from the viewpoint of further improving the ease and speed of construction by minimizing on-site construction as much as possible, it is preferable that the bearing portion is made of a precast member.
[0018]
In this case, from the viewpoint of securing a sufficient strength that can resist the large compressive force received from the pile and the structure foundation, it is preferable that the supporting pressure portion is formed by disposing a steel material on the outer edge portion. .
[0019]
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.
[0020]
Moreover, from the viewpoint of resisting the pulling force between the pile and the structure foundation, the pile head is provided with a core steel material (core rebar, etc.) that is fixed to the structure foundation via the bearing section. Is preferred.
[0021]
It should be noted that the provision of a core steel material that transmits the pulling force and horizontal force between the pile and the structure foundation via the bearing section does not hinder the support type of the structure foundation by the pile head as described above. Absent.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[0023]
Embodiment 1
FIG. 1 is a diagram showing a schematic configuration when a support structure for a structure foundation according to Embodiment 1 of the present invention is in service (FIG. 1 (a) is a cross-sectional view, FIG. 1 (b) is A in FIG. 1 (a). Direction arrow view).
[0024]
In addition, the following explanation is about the support structure of the structure foundation using the cast-in-place concrete pile as the pile, but the support structure of the structure foundation using the pile other than the cast-in-place concrete pile is also valid. It has sex. In addition, the structure foundation has validity with respect to a form using a footing foundation and other foundations.
[0025]
In this Embodiment 1, the cast-in-place concrete pile 1 is located on the upper side adjacent to the pile main body portion 1b and the pile main body portion 1b, the tip of which reaches the support layer, as shown in FIG. 1 (a). It is comprised from the pile head 1a which is.
[0026]
As shown in FIG. 1, the support structure of the structure foundation is to support the foundation 2 while placing it on the pile head 1a in the bearing section 2a, and the pile of the cast-in-place concrete pile 1 The head portion 1a is composed of a head supporting portion 2a provided under the foundation 2 and integrally therewith. Hereinafter, each component will be described in detail.
[0027]
(1) Pile head 1a
As shown in FIG. 1A, the pile head 1a is an upper end portion of the cast-in-place concrete pile 1 that receives a load from the foundation 2, and is a portion that is located on the upper side adjacent to the pile body portion 1b. . However, the pile head 1a temporarily exists as a surplus portion including slime immediately after the cast-in-place concrete pile 1 is placed as underwater concrete, but does not include a portion that is removed by the processing by the lifting method.
[0028]
Here, as shown in the figure, a reinforcing steel cage 10 for securing strength as a pile foundation is disposed on the outer peripheral portion of the pile head 1a. And in the part in the pile head 1a among this reinforcing bar cage 10, the reinforcing bar 12 for shear reinforcement is densely arranged compared with the pile main-body part 1b. This is because the bearing head 2a receives a load from the foundation 2 by the bearing section 2a having a smaller area than the cross section of the pile body section 1b, so that a considerably large bearing stress acts on the pile head 1a. This is because it is necessary to prevent destruction of the head 1a.
[0029]
In addition, this rebar basket 10 is not fixed with respect to the foundation 2, and does not prevent the support form of the foundation 2 by the pile head 1a called mounting.
[0030]
(2) Pressure bearing part 2a
As shown in FIG. 1, the support pressure part 2 a is a part that protrudes downward from the bottom surface of the foundation 2, and is a part that is directly placed on the pile head 1 a.
[0031]
As shown in the figure, the bearing portion 2a has a lower end surface 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 an upper end surface that is fixed below the foundation 2. Is wider than the lower end surface and within the range of the lower region of the lower end surface.
[0032]
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 narrower than the area of the upper end surface. Presents.
[0033]
As shown in the figure, the bearing portion 2a receives the load from the foundation 2 at the lower end surface having an area smaller than the area of the upper end surface, so that it is sufficient to resist a large compressive force. Must have strength.
[0034]
Therefore, in the first embodiment, the concrete compressive strength of the bearing section 2a is determined in consideration of the compressive force and horizontal force received by the bearing section 2a.
[0035]
Here, the degree of smoothness at the lower end surface of the bearing section 2a is such that a horizontal force can be transmitted by the frictional force generated between the bearing section 2a and the pile head 1a.
[0036]
In addition, as a modified example of the pressure bearing portion 2a in the first embodiment, although not shown, an inverted truncated pyramid shape having a polygonal shape in plan view can be exemplified.
[0037]
When such an inverted truncated pyramid shape is used, since the bearing part 2a receives a large compressive force, the lower end surface of the bearing part 2a is within the range of the top surface of the pile head 1a which is a substantially horizontal surface. Need to be in.
[0038]
Specifically, it must be smaller than the polygon inscribed in the top face of the pile head 1a having a circular shape.
[0039]
Next, the construction method of the structure foundation support structure according to the first embodiment will be described with reference to FIG.
[0040]
First, after the cast-in-place concrete pile 1 is placed, the pile head 1a is subjected to a suspension process in order to remove the excess pile head 1a. Since the suspension process at this time has the structure which mounts the bearing part 2a on the pile head 1a, since there is no reinforcing bar 10 in the surplus of the pile head 1a, the original main reinforcement 11 and band 12 It can be easily performed within a range that does not take up to the position, and it does not take much time.
[0041]
Then, when the top surface of the pile head 1a is finished to a substantially horizontal surface, the hanging process of the pile head 1a is finished.
[0042]
Subsequently, while rolling back the area excluding the pile head 1a with high quality soil, rolling and rolling the foundation crushed stone according to the height of the bottom of the foundation 2, and then leveling Place concrete.
[0043]
At this time, the periphery of the pile head 1a is formed in a slip shape so that the portion to be the pressure bearing portion 2a has an inverted truncated cone shape.
[0044]
Next, with respect to the portion included in the foundation 2 in the bearing part 2a, the formwork is erected and the reinforcing bars are assembled, and then the concrete of the bearing part 2a is placed.
[0045]
In this Embodiment 1, since the concrete compressive strength of the bearing part 2a of the foundation 2 is set considerably larger than parts other than the bearing part 2a, other than the concrete of the bearing part 2a and the bearing part 2a. The part of concrete is to be constructed separately.
[0046]
Next, after the curing period of the concrete of the bearing part 2a has passed, after assembling the reinforcing bars and the mold for the parts other than the bearing part 2a of the foundation 2, the parts other than the bearing part 2a Place concrete.
[0047]
And after the curing period of the concrete of parts other than the bearing part 2a passes, construction of the support structure of a structure foundation is completed.
[0048]
Next, the operation of the structure foundation support structure according to Embodiment 1 will be described with reference to FIG.
[0049]
First, when an earthquake occurs, 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 through the cast-in-place concrete pile 1.
[0050]
At this time, since the cast-in-place concrete pile 1 and the foundation 2 have different natural periods, they attempt to vibrate independently. Then, since a frictional force is generated between the pile head 1a and the bearing pressure part 2a, the cast-in-place concrete pile 1 and the foundation 2 receive a horizontal force with each other.
[0051]
However, the support structure of the structure foundation is a structure in which the foundation 2 and the pile head 1a have a large degree of freedom in rotation and a low degree of fixation, and the foundation 2 is mounted on the pile head 1a in the bearing portion 2a. It is a structure that only puts.
[0052]
Moreover, it is the structure where the load from the foundation 2 is received by the lower end surface of the bearing part 2a of an area narrower than the area of the top face of the pile head 1a.
[0053]
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.
[0054]
As explained above, according to the structure foundation support structure according to the first embodiment, in addition to the construction of the original cast-in-place concrete pile 1, the pile head 1 a is subjected to emergency treatment such as suspension treatment or concrete placement. This makes it possible to avoid complicated and time-consuming work.
[0055]
Therefore, the fixing degree of the pile head can be easily adjusted, and the bending moment acting on the cast-in-place concrete pile 1 and the foundation 2 is reduced while maintaining the effect of receiving a large horizontal force. At the same time, it became possible to ensure the ease and speed of construction.
[0056]
Embodiment 2
FIG. 2 is a diagram showing a schematic configuration in use of a support structure for a structure foundation according to Embodiment 2 of the present invention (FIG. 2 (a) is a cross-sectional view, FIG. 2 (b) is B in FIG. 2 (a). Direction arrow view). Components similar to those in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and detailed description thereof is omitted here.
[0057]
The basic structure of the support structure for the structure foundation is substantially the same as that of the first embodiment. However, unlike the first embodiment, as a type of pile that supports the foundation 2, a band 12 for shear reinforcement is used. The steel pipe concrete pile 3 formed by filling the hollow portion of the steel pipe pile 3a which is not necessary with the concrete 3b is adopted, and in addition, the bearing portion 2a is used as a steel material on the outer edge portion of the precast concrete block 4a which is a precast member. The steel pipe 4b is precast concrete 4 provided with a steel pipe 4b.
[0058]
Therefore, according to the support structure of the structure foundation according to the second embodiment, since the precast concrete block 4a is used for the bearing portion 2a, the on-site construction is simplified and the construction is easy and quick. Further, since the steel tube-wound precast concrete 4 in which the steel material 4b is disposed on the outer edge portion of the precast concrete block 4a is used, a large compressive force received from the steel tube concrete pile 3 and the foundation 2 is used. It is possible to ensure sufficient strength to resist the resistance.
[0059]
In this precast concrete block 4a, the outer peripheral end is chamfered, but this has an effect of preventing the outer peripheral end of the bearing portion 2a from being chipped.
[0060]
【The invention's effect】
According to the support structure for a structure foundation according to the present invention, it is possible to easily adjust the fixing degree of the pile head and to ensure the ease and speed of construction.
[Brief description of the drawings]
1A and 1B are diagrams showing a schematic configuration when a structure foundation support structure according to Embodiment 1 of the present invention is in use (FIG. 1A is a cross-sectional view, and FIG. 1B is a diagram in FIG. 1A); (A direction arrow view).
FIGS. 2A and 2B are diagrams showing a schematic configuration when a structure foundation support structure according to Embodiment 2 of the present invention is in use (FIG. 2A is a cross-sectional view, and FIG. 2B is a diagram in FIG. 2A); (A direction arrow view).
FIGS. 3A and 3B are diagrams showing a schematic configuration when a support structure for a structure foundation according to the prior art is in service (FIG. 3A is a cross-sectional view, and FIG. 3B is a view in the direction of arrow A in FIG. 3A); ).
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Cast-in-place concrete pile 1a ... Pile head 1b ... Pile main-body part 2 ... Foundation (structure foundation)
2a ... bearing part 3 ... steel pipe concrete pile 3a ... steel pipe pile 3b ... concrete 4 ... steel pipe winding precast concrete (bearing part)
4a ... Precast concrete block 4b ... Steel pipe (steel)
DESCRIPTION OF SYMBOLS 10 ... Reinforcement cage | basket 11 ... Main reinforcement 12 ... Band reinforcement 101 ... Cast-in-place concrete pile 101a ... Pile head 101b ... Pile main-body part 101c ... Bearing part 102 ... Foundation 111 ... Main reinforcement 112 ... Band reinforcement 121 ... Range 122 ... Range

Claims (2)

Pile head, and includes a bearing capacity portion is a reverse frustum shape is provided to protrude downward from the bottom surface of the structure foundation, on the top surface of the substantially horizontal the pile head of the structure underlying the said supporting pressure part Support structure for a structure foundation, characterized in that it is supported while being placed on the surface. The support structure for a structure foundation according to claim 1, wherein the pile head has densely arranged streaks compared to the pile main body .

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