JP7401363B2 - building foundation structure - Google Patents

Description

The present invention relates to the foundation structure of a building.

As the foundation structure of a building, there are two types: pile foundation, in which the building is supported by a large number of piles, and direct foundation, in which the building is supported by ground reaction force.
For pile foundations, the number of piles is calculated based on the assumption that the piles will support the entire weight of the building, so the number of piles used becomes extremely large, which increases construction time and costs. . In addition, with direct foundations, the entire weight of the building is supported by the ground (ground reaction force), so it cannot be used if the ground does not have sufficient bearing capacity.
Therefore, a pile draft foundation is known as a foundation structure that combines a pile foundation and a direct foundation (for example, see Patent Document 1).

Japanese Patent Application Publication No. 2004-68253

However, in the pile draft foundation described in the foundation structure of a structure in Patent Document 1, the pile heads of the piles are connected to the lower surface of the upper part of the foundation made of foundation concrete, so the upper part of the foundation and the pile are connected. I needed to. This made building construction complicated.
Additionally, if a horizontal force is generated on a building during an earthquake, if the top of the foundation and the pile are connected, the exchange of forces between the top of the foundation and the pile head becomes complicated, making building design difficult. There was a case.
Therefore, if the structure is such that the piles are not connected to the upper part of the foundation, the upper part of the foundation may slide significantly if a large horizontal force is applied to the building.
The present invention has been made in view of the above circumstances, and when a pile draft foundation is used to support a building with a plurality of piles and the upper part of the foundation, it facilitates the construction and design of the building, and also reduces the excessive burden on the upper part of the foundation. The purpose is to provide a building foundation structure that suppresses slipping.

In order to achieve the above-mentioned object, the present invention provides a foundation structure for a building that supports the building by a plurality of piles and an upper part of the foundation, in which a plurality of recesses that are open at the bottom are provided on the lower surface of the upper part of the foundation, and The pile head of each of the plurality of piles is inserted into the plurality of recesses, and between the outer circumferential surface of the pile head and the inner circumferential surface of the recess, there is a gap between the upper part of the foundation and the pile head. A gap is provided to allow horizontal movement, and an upper layer of ground, which is ground to which a pile draft foundation can be applied, is provided directly below the upper part of the foundation.

When a building is supported by a plurality of piles and the upper part of the foundation using a pile draft foundation, it is advantageous in facilitating the construction and design of the building and in suppressing excessive slipping of the upper part of the foundation.

FIG. 1 is a plan cross-sectional view showing the basic structure of a building according to the first embodiment. FIG. 1 is a side sectional view showing the foundation structure of a building according to the first embodiment. (A) is a cross-sectional view showing the structure of a pile and a footing according to the first embodiment, and (B) is a cross-sectional view when horizontal force is generated in the building in (A). It is a sectional view showing the composition of the pile and footing concerning a 2nd embodiment. It is a sectional view showing the composition of the pile and footing concerning a 3rd embodiment. It is a sectional view showing the composition of the pile and footing concerning a 4th embodiment. It is a sectional view showing the composition of the pile and footing concerning a 5th embodiment. It is a sectional view showing the composition of the pile and footing concerning a 6th embodiment. It is a sectional view showing the composition of the pile and footing concerning a 7th embodiment. It is a sectional view showing the composition of the pile and footing concerning an 8th embodiment. FIG. 7 is a plan cross-sectional view showing the basic structure of a building according to a ninth embodiment. It is a side sectional view showing the foundation structure of a building concerning a 9th embodiment.

(First embodiment)
Embodiments of the present invention will be described below with reference to the drawings.
The building foundation structure of the present invention is a building foundation structure using a pile draft foundation that supports the building with a plurality of piles and an upper part of the foundation (a portion of the building foundation structure that does not include piles).

In this embodiment, a case will be described in which the upper ground, which is the surface side of the ground G on which the building foundation structure 1 is constructed, is a ground to which a pile draft foundation cannot be applied (see FIG. 2).
Grounds to which pile draft foundations cannot be applied include, for example, soft ground made of mud or soft soil containing a large amount of water, which cannot support the load of the building and may cause the building to sink.
The ground G in this embodiment is a ground that has a support layer to which a pile draft foundation can be applied below a soft layer made of soft ground to which a pile draft foundation cannot be applied.
Therefore, in this embodiment, the soft ground that is the upper ground is improved to improve the ground to which the pile draft foundation can be applied, that is, the ground that has the same properties as the ground to which the pile draft foundation can be applied. After forming the upper ground G1, the foundation structure 1 of the building is constructed.

The ground improvement in this embodiment is performed using a method using a cement-based solidifying material, such as a fluidization method or a shallow mixing method.
The fluidization treatment method involves mixing adjusted mud (muddy water made by adding a specified amount of water to fine-grained soil similar to clay or silt) and solidifying material in an appropriate proportion to increase the fluidity of the generated soil. This is a construction method in which the material is made into a fluid state and poured directly or by pumping.
In addition, the shallow layer mixing method, also known as surface layer improvement, excavates the ground to be improved using a backhoe, etc., and mixes lime, cement, cement-based hardening agent, etc. to a depth of about 50 cm to 3 m. backfill while doing so. When backfilling, the method uses rollers and rammers to thoroughly compact and compact the area at intervals of approximately 30cm to 50cm thick.

As shown in FIGS. 1 to 3(A) and (B), the building foundation structure 1 of this embodiment is composed of a plurality of piles 10 and a foundation upper part 20A. In this embodiment, the upper foundation 20A is a raft composed of a plurality of footings 22, pressure plates 24, and foundation beams 26.
FIG. 2 is a side sectional view taken along the line AA of the plan sectional view of FIG.
Immediately below the foundation upper part 20A, the above-mentioned improved ground, in this embodiment, the upper ground G1, which is improved from soft ground, is provided.
Crushed stone, waste concrete, etc. (not shown) are provided on the upper ground G1.

The pile 10 is a steel pipe pile, a concrete pile, or the like, and is formed in a cylindrical shape having a predetermined length and diameter that does not reach the support layer. In the longitudinal direction of the cylindrical pile 10, a portion near the footing 22 is referred to as a pile head 12.
The piles 10 are driven into the ground G at predetermined intervals in the horizontal direction, and the pile heads 12 protrude upward from the upper ground G1. The vertical length (vertical length) of this protruding pile head 12 is, for example, about 10 cm.
The piles can be either ready-made piles or cast-in-place piles.

A sliding material 14 is attached to the upper surface of the pile 10, that is, the upper surface of the pile head 12.
The sliding material 14 makes it easier to slide on the member in contact with the upper surface, and is made of, for example, polytetrafluoroethylene (Teflon: registered trademark), which is a fluororesin (fluorocarbon resin) consisting only of fluorine atoms and carbon atoms. It is composed of materials such as.

The footing 22 is a rectangular parallelepiped-shaped member made of reinforced concrete, and is arranged above the pile head 12 of each of the plurality of piles 10, and its lower surface is in contact with the upper surface of the upper ground G1.
The plurality of footings 22 are connected by foundation beams 26 near the upper surface of the upper ground G1, and columns 28 constituting the upper structure are erected on the upper surface of each of the plurality of footings 22.
The pressure plate 24 is a plate-shaped member made of reinforced concrete and has a predetermined thickness, and is provided in an area surrounded by the foundation beams 26 that connect the plurality of footings 22 in a plan view.
The pressure plate 24 of this embodiment is provided in a rectangular area surrounded by four foundation beams 26 that connect the four footings 22.

Further, each of the plurality of footings 22 is provided with a cylindrical recess 22A in the center of the lower surface thereof, which is made up of an inner circumferential surface 2202 and a bottom surface 2204 that connects the upper part of the inner circumferential surface 2202, and is open at the bottom. There is.
The pile heads 12 of the plurality of piles 10 are respectively inserted into the plurality of recesses 22A.
The bottom surface 2204 of the recess 22A is in contact with the upper surface of the sliding material 14 attached to the upper surface of the pile head 12. The friction coefficient between the sliding material 14 and the bottom surface 2204 of the recess 22A is smaller than the friction coefficient between the top surface of the pile head 12 and the bottom surface 2204 of the recess 22A. In other words, the sliding material 14 is provided to reduce the frictional force between the top surface of the pile head 12 and the bottom surface 2204 of the recess 22A.
Further, the main pile reinforcement (not shown) constituting the pile 10 is installed inside the pile 10 without being fixed to the footing 22.
The plurality of footings 22 have a width wider than the foundation beam 26, and transmit the load of the building to each of the plurality of piles 10.

Further, a cylindrical steel pipe 30 is provided on the inner circumferential surface 2202 of the recess 22A, with the axial direction being in the vertical direction.
The steel pipe 30 has a thickness of approximately 5 mm to 10 mm, for example, and its length in the vertical direction (length in the axial direction) is approximately equal to the length of the pile head 12 protruding from the upper ground G1. .
Here, in this embodiment, since the steel pipe 30 is provided on the inner peripheral surface 2202 of the recess 22A provided in the footing 22, the inner peripheral surface of the recess 22A is the inner peripheral surface 3002 of the steel pipe 30. .

A gap C is provided between the outer peripheral surface 1202 of the pile head 12 inserted into the recess 22A and the inner peripheral surface 3002 of the recess 22A to allow relative horizontal movement between the foundation upper part 20A and the pile 10. ing.
An annular gap filler 40 is provided in the gap C to ensure a space for relative horizontal movement between the foundation upper part 20A and the pile head 12.
The gap filler 40 prevents the concrete from entering the gap C when pouring concrete to provide the footing 22 above the pile 10 and preventing the relative horizontal movement between the foundation upper part 20A and the pile head 12. It is placed in the gap C so that the space does not run out, that is, to ensure a space for movement.
The gap filler 40 is, for example, Styrofoam, which is a material with a relatively small Poisson's ratio and is softer than concrete.

The inner diameter of the recess 22A is determined by considering the size of the superstructure and the relationship with the outer diameter of the pile 10. For example, if the outer diameter of the pile 10 is d and the inner diameter D of the recess 22A is the following: It is formed so as to satisfy formula (1).

D=1.1d~1.5d...(1)

Therefore, for example, if the outer diameter of the pile 10 is 1 m, the inner diameter of the recess 22A is 1.1 m to 1.5 m, and therefore the annular gap C with a radial width of about 5 cm to 25 cm is It is provided between the outer circumferential surface 1202 of the portion 12 and the inner circumferential surface 3002 of the recessed portion 22A.

In this way, in the building foundation structure 1 of the present embodiment, there is an upper ground G1 directly below the foundation upper part (raft) 20A including a plurality of footings 22 and a pressure plate 24, and a plurality of foundation structures below the plurality of footings 22. Piles 10 have been driven.
Therefore, when the foundation upper part 20A receives the load of the building, it transmits the vertical load to the plurality of piles 10. Therefore, the load of the building is supported by both the upper foundation 20A and the plurality of piles 10.

Further, in the building foundation structure 1 of the present embodiment, the pile head 12 of the pile 10 is inserted into the recess 22A provided on the lower surface of each of the plurality of footings 22, and the sliding material attached to the pile head 12 14 and the bottom surface 2204 of the recess 22A are in contact with each other. A gap C is provided between the outer circumferential surface 1202 of the pile head 12 and the inner circumferential surface 3002 of the recess 22A, and the gap filler 40 is provided in the gap C.
Therefore, for example, when an earthquake occurs, the upper foundation 20A receives the horizontal force F of the building and moves horizontally with respect to the piles 10, as shown in FIG. Frictional force is generated between the lower surface and the upper surface of the upper ground G1.
On the other hand, since the sliding material 14 is attached to the top surface of the pile head 12, the frictional force between the top surface of the pile head 12 of the pile 10 and the bottom surface 2204 of the recess 22A of the footing 22 is reduced.
As a result, if a relatively small earthquake occurs, the foundation upper part 20A can move horizontally with respect to the pile 10 due to the gap C, but if a relatively large earthquake occurs, the foundation upper part 20A can move horizontally with respect to the pile 10. Since the upper portion 20A moves largely in the horizontal direction, the inner circumferential surface 3302 of the recess 22A comes into contact with the outer circumferential surface 1202 of the pile head 12 of the pile 10, as shown in FIG. 3(B).
In other words, even in the event of an earthquake, the building load (vertical load) is supported by both the upper foundation 20A and the plurality of piles 10, but the horizontal force of the building is supported by the friction of the upper foundation 20A in the case of a small earthquake. In the case of a large earthquake, the pile 10 acts as a resisting force.

Next, an overview of an example of a method for constructing the building foundation structure 1 will be explained.
First, a plurality of piles 10 each having a sliding material 14 attached to the upper surface are placed at a desired position on the improved upper ground G1, and the pile head 12 of a predetermined length is projected from the upper ground G1 and driven. Set up
Next, crushed stone is laid on top of the upper ground G1, and on top of that crushed concrete is poured to serve as a base on which markings and formwork will be placed to determine the position.
Then, the gap filler 40 is attached to the outer circumferential surface 1202 of each pile head 12 of the plurality of piles 10, and the steel pipe 30 is installed on the outer circumference of the gap filler 40.
The method of attaching the gap filler 40 is, for example, by dividing the annular gap filler 40 into two parts by diameter, and fitting them together from opposite positions with the pile head 12 in between, and then attaching the ends with adhesive. Join with etc.
Next, a plurality of footings 22 are arranged above each of the plurality of piles 10, and concrete is poured so as to cover the pile head 12, the gap filler 40, and the steel pipe 30, and the plurality of footings 22 are installed. .
Then, the foundation beams 26 and the pressure plates 24 are reinforced, a plurality of foundation beams 26 connecting the plurality of footings 22 are provided, and concrete that will become the pressure plates 24 is placed in the area surrounded by the foundation beams 26.
Thereafter, columns 28 are erected on the upper surfaces of the plurality of footings 22, and a superstructure including beams, slabs, and columns of the upper floor is constructed.

As described above, according to the building foundation structure 1 according to the first embodiment, the pile heads 12 of each of the plurality of piles 10 are connected to the plurality of piles provided on the lower surface of the plurality of footings 22, which are the foundation upper part 20A. They are respectively inserted into the recesses 22A. The main reinforcement of each of the plurality of piles 10 is not fixed to the plurality of footings 22, and the bottom surface 2204 of the recess 22A is in contact with the upper surface of the sliding material 14 attached to the upper surface of the pile head 12.
Therefore, while maintaining the characteristics of the pile draft foundation structure in which the building load (vertical load) is supported by both the foundation upper part (raft) 20A including the plurality of footings 22 and pressure plates 24 and the plurality of piles 10, The horizontal force of the building that sometimes occurs is difficult to be transmitted to the plurality of piles 10.
For this reason, the complicated construction of the building by making the pile main reinforcement of the pile 10 swallow into the footing 22 and joining the foundation upper part 20A and the pile 10, and the exchange of force between the foundation upper part 20A and the pile head 12 are avoided. This is advantageous in simplifying the construction and design of buildings by avoiding difficult designs that would otherwise require consideration.

Further, between the outer circumferential surface 1202 of the pile head 12 and the inner circumferential surface 3002 of the recess 22A, there is a gap C and a space that allows the relative movement of the foundation upper part 20A and the plurality of piles 10 in the horizontal direction. It is secured through the material 40.
Therefore, when a relatively small earthquake occurs, horizontal force is generated in the building and the upper foundation 20A can move horizontally with respect to the plurality of piles 10, so the friction force of the upper foundation 20A against the upper ground G1 causes the building to move. Can resist horizontal forces. At this time, the plurality of piles 10 do not move following the upper foundation 20A, which is advantageous in suppressing deformation of the piles 10.
In addition, when a relatively large earthquake occurs, a large horizontal force is generated in the building, and the upper part of the foundation 20A moves significantly in the horizontal direction, causing the inner circumferential surface 3002 of the recess 22A to change to the outer circumferential surface 1202 of the pile head 12 of the pile 10. , the plurality of piles 10 act as a resistance force, which is advantageous in suppressing excessive slipping of the upper part of the foundation 20A.

In addition, since the sliding material 14 is attached to the upper surface of the plurality of piles 10, that is, the upper surface of the pile head 12, the foundation upper part 20A will slide against the plurality of piles 10 when horizontal force is generated on the building. The frictional force between the upper surface of the pile head 12 of the plurality of piles 10 and the bottom surface 2204 of the recess 22A provided in the plurality of footings 22 is reduced.
Therefore, it is possible to suppress the horizontal force (inertial force) of the building during an earthquake from being transmitted from the upper foundation 20A to the plurality of piles 10, and to reduce the horizontal force borne by the plurality of piles 10. Therefore, it becomes possible to reduce the pile diameter of the plurality of piles 10, which is advantageous in reducing costs.

Further, since the steel pipe 30 is provided on the inner peripheral surface 2202 of the recess 22A provided on the lower surface of the plurality of footings 22, the inner peripheral surface 3002 of the recess 22A (inner peripheral surface 3002 of the steel pipe 30) is connected to the pile 10. Damage to the plurality of footings 22 when they come into contact with the outer circumferential surface 1202 of the head 12 can be suppressed.

In addition, since the gap filler 40 is provided in the gap C provided between the outer circumferential surface 1202 of the pile head 12 and the inner circumferential surface 3002 of the recess 22A, the gap filling material 40 is provided at the time of concrete pouring when producing the footing 22. Intrusion of concrete into the gap C can be suppressed.

Further, in the building foundation structure 1, it is preferable that an upper layer of ground G1, which is the ground to which a pile draft foundation can be applied, is provided directly below the upper part of the foundation 20A.
However, in this embodiment, since the upper ground is ground to which the pile draft foundation cannot be applied, the upper ground is improved to become upper ground G1 to which the pile draft foundation can be applied.
Therefore, even if the upper ground is a ground to which a pile draft foundation cannot be applied, the building foundation structure 1 of this embodiment using a pile draft foundation can be applied by improving the ground.
Compared to a general ground that has not been improved, the provision of the upper ground G1, which is made of improved ground, has a higher vertical support capacity for the building load, and a higher level of support in the event of horizontal force during an earthquake. This is advantageous in strictly evaluating and accurately understanding the horizontal frictional force of the foundation upper part 20A against the upper ground G1.
Moreover, in the upper ground G1 made of improved ground, it is possible to suppress unevenness in the properties of the upper ground G1, which is advantageous in reliably transmitting the load of the building to each of the plurality of piles 10.

(Second embodiment)
In the first embodiment, the steel pipe 30 was provided on the inner peripheral surface 2202 of the recess 22A provided on the lower surface of the footing 22, whereas in the second embodiment, the steel pipe 30 was provided on the inner peripheral surface 2202 of the recess 22A provided on the lower surface of the footing 22. The difference is that a steel pipe is provided on the outer peripheral surface 1202 of No. 12.
In the following description of the embodiment, parts and members similar to those in the first embodiment are given the same reference numerals, and the description thereof will be omitted, and emphasis will be placed on parts that are different from the first embodiment. Explain.

As shown in FIG. 4, in the building foundation structure 2 of this embodiment, a steel pipe 32 is provided on the outer peripheral surface 1202 of the pile head 12 of the pile 10.
Therefore, a gap C is provided between the outer circumferential surface 3202 of the steel pipe 32 and the inner circumferential surface 2202 of the recess 22A, which allows the relative horizontal movement of the foundation upper part 20A and the plurality of piles 10. C is provided with an annular gap filler 40 as in the first embodiment.

When constructing the foundation structure 2 of the building according to the present embodiment, after driving a plurality of piles 10 into the ground G and placing crushed stone or waste concrete, the outer peripheral surface of each pile head 12 of the plurality of piles 10 is The steel pipe 32 is attached to the steel pipe 1202, and the gap filler 40 is attached to the outer peripheral surface 3202 of the steel pipe 32.
Then, similarly to the first embodiment, a plurality of footings 22 are installed, foundation beams 26 are provided, and pressure plates 24 are cast. After that, the pillars 28 are erected and the superstructure is constructed.

As described above, according to the building foundation structure 2 according to the second embodiment, since the steel pipe 32 is provided on the outer circumferential surface 1202 of the pile head 12 of the plurality of piles 10, the inner circumferential surface of the recess 22A It is possible to suppress damage to the pile heads 12 of the plurality of piles 10 when the pile heads 1202 of the piles 10 come into contact with the outer circumferential surface 1202 of the pile heads 12 of the piles 10.
Also, in this embodiment, effects other than those obtained by providing the steel pipe 30 of the first embodiment are produced.

(Third embodiment)
In the first embodiment, the steel pipe 30 is provided on the inner peripheral surface 2202 of the recess 22A provided on the lower surface of the footing 22, and in the second embodiment, the steel pipe 30 is provided on the outer peripheral surface 1202 of the pile head 12 of the pile 10. Whereas the steel pipe 32 was provided, the third embodiment differs in that steel pipes are provided on both the inner circumferential surface 2202 of the recess 22A and the outer circumferential surface 1202 of the pile head 12.

As shown in FIG. 5, in the building foundation structure 3 of this embodiment, a steel pipe 30 is provided on the inner peripheral surface 2202 of the recess 22A provided on the lower surface of the plurality of footings 22, and the pile cap of the pile 10 A steel pipe 32 is provided on the outer peripheral surface 1202 of the portion 12 .
Therefore, a gap C is provided between the inner peripheral surface 3002 of the steel pipe 30 and the outer peripheral surface 3202 of the steel pipe 32, which allows the relative horizontal movement of the upper foundation 20A and the plurality of piles 10. C is provided with an annular gap filler 40 as in the first embodiment.

When constructing the foundation structure 3 of a building according to this embodiment, after driving a plurality of piles 10 into the ground G and placing crushed stone or waste concrete, the outer circumferential surface 1202 of the pile head 12 of the plurality of piles 10 is The steel pipe 32 is attached, the gap filler 40 is attached to the outer circumferential surface 3202 of the steel pipe 32, and the steel pipe 32 is further installed on the outer circumferential surface 4002 of the gap filler 40.
Then, similarly to the first embodiment, a plurality of footings 22 are installed, foundation beams 26 are provided, and pressure plates 24 are cast. After that, the pillars 28 are erected and the superstructure is constructed.

As described above, according to the building foundation structure 3 according to the third embodiment, the inner peripheral surface 2202 of the recess 22A provided on the lower surface of the plurality of footings 22 and the pile head 12 of the plurality of piles 10 are Since the steel pipes 30 and 32 are provided on the outer circumferential surface 1202, when the inner circumferential surface 3002 of the recess 22A contacts the outer circumferential surface 3202 of the steel material 32 provided on the pile head 12 of the pile 10, the plurality of footings 22 Also, damage to the pile heads 12 of the plurality of piles 10 can be suppressed.
Also, in this embodiment, effects other than those obtained by providing the steel pipe 30 of the first embodiment are produced.

(Fourth embodiment)
In the first embodiment, the steel pipe 30 is provided on the inner peripheral surface 2202 of the recess 22A provided on the lower surface of the footing 22, and in the second embodiment, the steel pipe 30 is provided on the outer peripheral surface 1202 of the pile head 12 of the pile 10. Whereas the steel pipe 32 was provided, the fourth embodiment differs in that no steel pipe is provided on either the inner circumferential surface 2202 of the recess 22A or the outer circumferential surface 1202 of the pile head 12. .

As shown in FIG. 6, in the building foundation structure 4 of this embodiment, no steel pipe is provided on either the inner circumferential surface 2202 of the recess 22A or the outer circumferential surface 1202 of the pile head 12. A gap C is provided between the inner peripheral surface 2202 and the outer peripheral surface 1202 of the pile head 12 to allow relative horizontal movement between the foundation upper part 20A and the plurality of piles 10. As in the first embodiment, an annular gap filler 40 is provided.

When constructing the foundation structure 4 of the building of this embodiment, after driving a plurality of piles 10 into the ground G and placing crushed stone or waste concrete, a gap is formed on the outer peripheral surface 1202 of the pile cap 12 of the plurality of piles 10. Filler material 40 is attached.
Then, similarly to the first embodiment, a plurality of footings 22 are installed, foundation beams 26 are provided, and pressure plates 24 are cast. After that, the pillars 28 are erected and the superstructure is constructed.

In this manner, the building foundation structure 4 according to the fourth embodiment does not include steel pipes, which is advantageous in facilitating construction and reducing costs.
Also, in this embodiment, effects other than those obtained by providing the steel pipe 30 of the first embodiment are produced.

(Fifth embodiment)
In the first embodiment, the steel pipe 30 is provided on the inner peripheral surface 2202 of the recess 22A provided on the lower surface of the footing 22, whereas in the fifth embodiment, the recess 22 is provided with a closed cylindrical pipe. The difference is that steel is provided.

As shown in FIG. 7, the steel material 34 of this embodiment is composed of a cylindrical steel pipe 36 and a cover plate 38 that closes one end of the steel pipe 36, and the other end is open. .
The steel material 34 is installed with the axial direction facing up and down, with the cover plate 38 on the upper side and the other open end on the lower side, with the lower part of the steel pipe 36 in contact with the upper ground G1.
In the building foundation structure 5 of this embodiment, a steel material 34 is installed so as to cover the pile heads 12 of a plurality of piles 10, and a sliding material 14 attached to the upper surface of the pile heads 12 is installed. The lower surface 3802 of the lid plate 38 is in contact with the upper surface.
Therefore, an annular space is formed by the outer peripheral surface 1202 of the pile head 12, the lower surface 3802 of the lid part 38, the inner peripheral surface 3602 of the steel pipe 36, and the upper surface of the upper ground G1, and this space is connected to the upper foundation 20A. This is a gap C that allows movement in the horizontal direction relative to the plurality of piles 10. A gap filler is not provided in the gap C in this embodiment.

When constructing the foundation structure 5 of the building according to the present embodiment, a plurality of piles 10 are driven into the ground G, crushed stone and waste concrete are placed, and then a steel material 34 is covered from above the pile 10 to cover the pile head 12. Place it like this. As a result, a gap C is formed around the outer periphery of the pile head 12 of the pile 10, with a space inside.
Then, similarly to the first embodiment, a plurality of footings 22 are installed, foundation beams 26 are provided, and pressure plates 24 are cast. After that, the pillars 28 are erected and the superstructure is constructed.

As described above, according to the building foundation structure 5 according to the fifth embodiment, the steel material 23 is provided so as to cover the pile head 12 of the pile 10, and the outer circumferential surface of the pile head 12 of the pile 10 is Since the gap C can be formed without attaching a gap filler to 1202, this is advantageous in terms of ease of construction. Note that instead of the steel material 23, a wooden frame made of wood having the same shape as the steel material 23 may be provided.
Furthermore, this embodiment also provides effects other than those obtained by providing the gap filler 40 of the first embodiment.

(Sixth embodiment)
In the first embodiment, an annular gap filler 40 was provided in the gap C provided between the outer circumferential surface 1202 of the pile head 12 and the inner circumferential surface 3002 of the recess 22A. The sixth embodiment differs in that the gap C is provided with a granular gap filler.

As shown in FIG. 8, in the building foundation structure 6 of this embodiment, a granular gap filler is used in the gap C provided between the outer circumferential surface 1202 of the pile head 12 and the inner circumferential surface 3002 of the recess 22A. 42 are provided.
The gap filler 43 is, for example, granular foamed polystyrene formed into a sphere, and is filled with a predetermined amount of foamed polystyrene that can fill the gap C.

When constructing the foundation structure 6 of the building according to the present embodiment, after driving a plurality of piles 10 into the ground G and arranging crushed stone or waste concrete, The steel pipe 30 is installed, and the gap C formed between the outer peripheral surface 1202 of the pile head 12 and the inner peripheral surface 3002 of the steel pipe 30 is filled with a gap filler 42 .
Then, similarly to the first embodiment, a plurality of footings 22 are installed, foundation beams 26 are provided, and pressure plates 24 are cast. After that, the pillars 28 are erected and the superstructure is constructed.

As described above, according to the building foundation structure 6 according to the sixth embodiment, in addition to the same effects as the first embodiment, the outer circumferential surface 1202 of the pile head 12 and the inner circumferential surface 3002 of the recess 22A Since the granular gap filler 42 is filled in the gap C provided between This is advantageous in improving convenience.
Further, by using the steel pipe 30 as a formwork, the gap C can be filled with the granular gap filler 42 without providing a separate formwork, which is advantageous in facilitating construction and reducing costs.

(Seventh embodiment)
In the first embodiment, an annular gap filler 40 was provided in the gap C provided between the outer circumferential surface 1202 of the pile head 12 and the inner circumferential surface 3002 of the recess 22A. The seventh embodiment differs in that the gap C is provided with a buffer material and a gap filler.

As shown in FIG. 9, in the building foundation structure 7 of this embodiment, an annular buffer material 44 is provided in the gap C provided between the outer circumferential surface 1202 of the pile head 12 and the inner circumferential surface 3002 of the recess 22A. and annular gap fillers 46A, 46B.
The buffer material 44 fills the gap C and buffers the relative horizontal movement between the upper foundation 20A and the plurality of piles 10, and is made of, for example, rubber, which is an elastic body with a Poisson's ratio close to 0.5. materials, etc.
The buffer material 44 is formed so that its length in the vertical direction (length along the axial direction of the steel pipe 30) is shorter than the length in the vertical direction (length in the axial direction) of the steel pipe 30. The material 44 is provided on the outer circumferential surface 1202 of the pile head 12 so that the center of the length in the vertical direction matches the center of the length in the vertical direction of the steel pipe 30.

The gap fillers 46A and 46B are, for example, annular foamed polystyrene, etc., as in the first embodiment.
The gap filler 46A is provided between the top surface of the buffer material 44 and the bottom surface 2204 of the recess 22A, and the gap buffer material 46B is provided between the bottom surface of the buffer material 44 and the top surface of the upper ground G1, This is to ensure a space that allows the cushioning material 44 to be deformed in the vertical direction.
In this embodiment, gap fillers 46A and 46B are provided on the outer circumferential surface 1202 of the pile head 12 so as to sandwich the buffer material 44 from above and below, so that the upper foundation 20A receives the horizontal force of the building and becomes horizontal. When moving in the direction, the buffer material 44 presses the gap fillers 46A and 46B, allowing them to deform and spread in the vertical direction.

When constructing the foundation structure 7 of the building according to the present embodiment, after driving a plurality of piles 10 into the ground G and arranging crushed stone or waste concrete, the outer circumferential surface 1202 of the pile head 12 of the plurality of piles 10 is Gap filler 46B, buffer material 44, and gap filler 46A are attached in order from the bottom, and steel pipe 30 is installed on the outer peripheral surfaces of buffer material 44 and gap fillers 46A and 46B.
The buffering material 44 is attached by, for example, forming the inner diameter of the buffering material 44 slightly smaller than the outer diameter of the pile head 12, and fitting it through the upper end of the pile head 12.
Then, similarly to the first embodiment, a plurality of footings 22 are installed, foundation beams 26 are provided, and pressure plates 24 are cast. After that, the pillars 28 are erected and the superstructure is constructed.

As described above, according to the building foundation structure 7 according to the seventh embodiment, the cushioning material 44 is provided in the gap C provided between the outer circumferential surface 1202 of the pile head 12 and the inner circumferential surface 3002 of the recess 22A. is provided, so when the upper foundation 20A moves horizontally due to horizontal force generated in the building during an earthquake, the cushioning material 44 pressed against the inner peripheral surface 3002 of the recess 22A acts as a resistance force. . Therefore, it is possible to suppress movement in the horizontal direction due to excessive slipping of the foundation upper part 20A.
Furthermore, in this embodiment, by providing the gap fillers 46A and 46B to sandwich the buffer material 44 from above and below, horizontal force is generated in the building during an earthquake, and the upper part of the foundation 20A moves in the horizontal direction. At this time, the cushioning material 44 pressed against the inner circumferential surface 3002 of the recess 22A is allowed to press the upper and lower gap fillers 46A and 46B and deform and spread in the vertical direction. Therefore, damage to the footing 22 due to the cushioning material 44 pressing against the bottom surface 2204 of the recess 22A provided in the footing 22 can be prevented.
In addition, gap fillers 46A and 46B are provided in the gap C between the outer circumferential surface 1202 of the pile head 12 and the inner circumferential surface 3002 of the recess 22A, with the cushioning material 44 in between. It is possible to prevent concrete from entering the gap C during concrete pouring when manufacturing.
Furthermore, this embodiment also provides effects other than those obtained by providing the gap filler 40 of the first embodiment.

In the seventh embodiment, gap buffer materials 46A and 46B are provided between the upper surface of the buffer material 44 and the bottom surface 2204 of the recess 22A, and between the lower surface of the buffer material 44 and the upper surface of the upper ground G1, respectively. However, it may be provided on either one of the two sides.
Even with this configuration, it is possible to allow the cushioning material 44 to deform and expand upward or downward when a horizontal force is generated in the building and the upper part of the foundation 20A moves in the horizontal direction. 22 damage can be prevented.

Further, instead of the gap filler 44, a space may be provided. That is, for example, by providing a formwork on the outer periphery 1202 of the pile head 12 at the upper and lower ends of the cushioning material 44 during construction, the space between the top surface of the cushioning material 44 and the bottom surface 2204 of the recess 22A and the bottom surface of the cushioning material 44 can be A space may be secured between the upper surface of the upper ground G1 and the upper surface of the upper ground G1.
Even with this configuration, it is possible to allow the cushioning material 44 to deform and spread upward and downward when a horizontal force is generated in the building and the upper part of the foundation 20A moves in the horizontal direction, and the footing 22 damage can be prevented.

(Eighth embodiment)
In the seventh embodiment, a buffer material 44 and gap fillers 46A and 46B are provided in the gap C provided between the outer circumferential surface 1202 of the pile head 12 and the inner circumferential surface 3002 of the recess 22A. In contrast, the eighth embodiment differs in that a cushioning material, which is a hollow annular body, is provided in the gap C.

As shown in FIG. 10, in the building foundation structure 8 of this embodiment, a hollow annular body is provided in the gap C provided between the outer peripheral surface 1202 of the pile head 12 and the inner peripheral surface 3002 of the recess 22A. A certain cushioning material 48 is provided.
The cushioning material 48 is, for example, a hollow annular body made of an elastic material such as thin rubber, and is attached to the outer circumferential surface 1202 of the pile head 12.

When constructing the foundation structure 8 of the building of this embodiment, after driving a plurality of piles 10 into the ground G and placing crushed stone or waste concrete, the outer circumferential surface 1202 of the pile head 12 of the plurality of piles 10 is The buffer material 48 is attached, and the steel pipe 30 is installed on the outer peripheral surface of the buffer material 48.
Then, similarly to the first embodiment, a plurality of footings 22 are installed, foundation beams 26 are provided, and pressure plates 24 are cast. After that, the pillars 28 are erected and the superstructure is constructed.

As described above, according to the building foundation structure 8 according to the eighth embodiment, a hollow annular shape is provided in the gap C provided between the outer circumferential surface 1202 of the pile head 12 and the inner circumferential surface 3002 of the recess 22A. Since the cushioning material 48 is provided as a body, when a horizontal force is generated in the building during an earthquake and the upper foundation 20A moves horizontally, the cushioning material 48 is pressed against the inner circumferential surface 3002 of the recess 22A. acts as a resistance force. Therefore, it is possible to suppress movement in the horizontal direction due to excessive slipping of the foundation upper part 20A.
In addition, since the cushioning material 48 of this embodiment has a hollow shape, when horizontal force is generated in the building during an earthquake and the foundation upper part 20A moves in the horizontal direction, it is pressed against the inner circumferential surface 3002 of the recessed portion 22A. It is allowed to deform inward. Therefore, damage to the footing 22 due to the cushioning material 48 pressing against the bottom surface 2204 of the recess 22A provided in the footing 22 can be prevented.
In addition, since a buffer material 48 is provided in the gap C provided between the outer circumferential surface 1202 of the pile head 12 and the inner circumferential surface 3002 of the recess 22A, the cushioning material 48 is provided during concrete pouring when creating the footing 22. It is possible to prevent concrete from entering the gaps.
Furthermore, this embodiment also provides effects other than those obtained by providing the gap filler 40 of the first embodiment.

(Ninth embodiment)
In the first embodiment, the upper foundation 20A is provided which has a plurality of footings 22 and a pressure plate 24 provided in an area surrounded by foundation beams 26 that connect the plurality of footings 22. The ninth embodiment differs in that the upper foundation 20B does not have a plurality of footings or foundation beams, but is provided with a mat slab having a predetermined thickness.

As shown in FIGS. 11 and 12, the building foundation structure 9 of this embodiment includes a plurality of piles 10 and an upper foundation 20B. In this embodiment, the upper foundation 20B is a mat slab 50.
FIG. 12 is a side sectional view taken along the line BB of the plan sectional view of FIG.
The mat slab 50 is a plate-like member made of reinforced concrete that is arranged above the pile head 12 of each of the plurality of piles 10 and has a size that matches the superstructure and a predetermined thickness.
A pillar 28 constituting the upper structure is joined to a desired position on the upper surface of the mat slab 50.
By using such a mat slab 50, an integral slab can be used as the foundation without providing a foundation beam or footing.
The mat slab 50 receives the load of the building as a whole and transmits the load of the building (vertical load) downward on the entire lower surface, so the plurality of piles 10 do not need to be provided evenly with respect to the mat slab 50. .
Although FIG. 11 shows an example in which 12 pillars 28 are evenly provided, the number and arrangement positions of the pillars can be determined according to the design of the building.

In addition, on the lower surface of the mat slab 50, similarly to the first embodiment, a cylindrical recess 22A is formed with an inner circumferential surface 2002 and a bottom surface 2204 connecting the upper part of the inner circumferential surface 2002, and is open at the bottom. There are several.
The pile heads 12 of the plurality of piles 10 are respectively inserted into the plurality of recesses 22A.
The bottom surface 2204 of the recess 22A is in contact with the top surface of the sliding material 14 attached to the top surface of the pile head 12, and the sliding material 14 has a friction coefficient between the top surface of the pile head 12 and the bottom surface 2204 of the recess 22A. is made smaller.
Further, the main pile reinforcements (not shown) that constitute each of the plurality of piles 10 are installed inside the piles 10 without being fixed to the mat slab 50.

In this way, in the building foundation structure 9 of this embodiment, there is an upper ground G1 directly below the foundation upper part (raft) 20B including the mat slab 50, and a plurality of piles 10 are driven into the ground G, and the recess 22A The top surface of the pile head 12 is in contact with the bottom surface 2204 of the pile head 12 via the sliding material 14.
Therefore, similarly to the first embodiment, when the upper foundation 20B receives the load of the building, it transmits the vertical load to the plurality of piles 10. Therefore, the load of the building is supported by both the upper foundation 20A and the plurality of piles 10.

Further, in the building foundation structure 9 of this embodiment, the pile heads 12 of the plurality of piles 10 are inserted into the plurality of recesses 22A provided on the lower surface of the mat slab 50, and the pile heads 12 are attached to the pile heads 12. The top surface of the sliding member 14 and the bottom surface 2204 of the recess 22A are in contact with each other. A gap C is provided between the outer circumferential surface 1202 of the pile head 12 and the inner circumferential surface 3002 of the recess 22A, and the gap filler 40 is provided in the gap C.
Therefore, as in the first embodiment, even when an earthquake occurs, the building load (vertical load) is supported by both the upper foundation 20B and the plurality of piles 10, but the horizontal force of the building is small. In the case of an earthquake, the friction force of the foundation upper part 20B provides resistance, and in the case of a large earthquake, the plurality of piles 10 act as a resistance force.

As described above, according to the building foundation structure 9 according to the ninth embodiment, in addition to the same effects as in the first embodiment, by using the mat slab 50 as the building foundation structure 9, the mat slab This is advantageous in improving the degree of freedom in the arrangement positions of the plurality of piles 10 with respect to 50 (foundation upper part 20B).

In the embodiment described above, the sliding material 14 is attached to the top surface of the pile head 12, but the sliding material 14 may be attached to the bottom surface 2204 of the recess 22A. When the sliding material 14 is attached to the bottom surface 2204 of the recess 22A, the friction coefficient between the sliding material 14 and the top surface of the pile head 12 is greater than the friction coefficient between the bottom surface 2204 of the recess 22A and the top surface of the pile head 12. It's also small. Furthermore, the sliding material 14 only needs to be attached at least at a position where the pile head 12 and the recess 22A are in contact with each other. Even with this configuration, when a horizontal force is generated in the building, the foundation upper part 20A slides against the plurality of piles 10, so the frictional force between the pile head 12 of the plurality of piles 10 and the recess 22A is reduced. Ru.

In addition, in the embodiment described above, an example was explained in which the foundation structure of a building is constructed when the upper ground is a ground to which a pile draft foundation cannot be applied, so the upper ground is improved and a pile drive foundation is constructed. The structure was such that the foundation structure of the building was constructed on top of the applicable ground, G1.
However, if the upper ground is applicable to the pile draft foundation without improving the ground, the foundation structure of the building may be constructed using that ground as it is as the upper ground G1.

1, 2, 3, 4, 5, 6, 7, 8, 9 Building foundation structure 10 Pile 12 Pile head 1202 Outer surface 14 Sliding material 20A Foundation upper part (raft)
20B Upper foundation (mat slab)
22 Footing 22A Recess 2202 Inner peripheral surface 2204 Bottom surface 24 Pressure plate 26 Foundation beam 28 Column 30, 32 Steel pipe 3002 Inner peripheral surface 34 Steel material 40, 42, 46A, 46B Gap filler 44, 48 Cushioning material 50 Mat slab C Gap G Ground G1 Upper ground

Claims (7)

A foundation structure of a building that supports the building with a plurality of piles and an upper part of the foundation,
A plurality of recesses open at the bottom are provided on the lower surface of the upper part of the foundation,
A pile head of each of the plurality of stakes is inserted into each of the plurality of recesses,
A gap is provided between the outer circumferential surface of the pile head and the inner circumferential surface of the recess to allow relative horizontal movement between the upper foundation and the plurality of piles,
A cushioning material, which is a hollow annular body made of an elastic body, is attached to the outer peripheral surface of the pile head and is provided to close the gap,
Immediately below the upper part of the foundation, an upper layer of ground is provided, which is the ground to which a pile draft foundation can be applied.
The basic structure of a building is characterized by: A sliding material is attached to the top surface of the pile head, and a friction coefficient between the sliding material and the bottom surface of the recess is smaller than a friction coefficient between the top surface of the pile head and the recess.
The foundation structure of a building according to claim 1, characterized in that: A sliding material is attached to the bottom surface of the recess, and a friction coefficient between the sliding material and the top surface of the pile head is smaller than a friction coefficient between the bottom surface of the recess and the pile head.
The foundation structure of a building according to claim 1, characterized in that: A steel pipe is provided on the outer peripheral surface of the buffer material .
The foundation structure of a building according to any one of claims 1 to 3, characterized in that: The upper part of the foundation includes a plurality of footings arranged above the pile heads of each of the plurality of piles, and a pressure plate provided in an area surrounded by a foundation beam connecting the plurality of footings in a plan view. has
The plurality of recesses are provided on the lower surface of the plurality of footings,
The foundation structure of a building according to any one of claims 1 to 4 , characterized in that: the foundation upper part is a matte slab having a predetermined thickness;
The foundation structure of a building according to any one of claims 1 to 4 , characterized in that: The above-mentioned upper ground is improved ground that has been improved so that pile draft foundations can be applied.
The foundation structure of a building according to any one of claims 1 to 6 , characterized in that:

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